Consider the following knowledge base
c(v,A,A).
c(l(X,A),B,l(X,C)) :- c(A,B,C).
e(X,A) :- c(B,l(X,C),A).
How to write the resolution trees corresponding to the knowledge base and the questions?
1. ?- e(X,l(p,l(q,v))).
2. ?- c(A,B,l(p,l(q,v))).
I don't understand anything, I don't know how to solve it, someone help me please.
I saw an example that I did understand, but I can't relate it to this exercise to be able to solve it.
In the method consultas(), how could I print the student's name and grades?
Until now what it prints to me are memory addresses, and not the name and grades.
Note: The map that receives this method is a map that returns a method called darDeAlta()which receives the data of a new student.
class Alumno {
private String nombre;
private int matricula;
private double calificaciones[];
Alumno(String nombre, int matricula, double calificaciones[]) {
this.calificaciones = calificaciones;
}
String getNombre() {
return nombre;
}
int getMat() {
return matricula;
}
double[] getCalif() {
return calificaciones;
}
void setCalif(double calif[]) {
calificaciones = calif;
}
}
public class Ejercicio {
Map<Integer, Alumno> alumnos = new TreeMap<>();
public Map darDeAlta() {
Scanner y = new Scanner(System.in);
//boolean b=false;
double d[] = new double[5];
System.out.println("Introduzca el nombre del estudiante");
String n = y.nextLine();
System.out.println("Introduzca su matricula (de 5 digitos)");
int m = y.nextInt();
System.out.println("Introduzca las calificaciones: \n");
for (int i = 0; i < 5; i++) {
System.out.println("Introduzca la calificacion");
d[i] = y.nextDouble();
}
if (alumnos.containsKey(m)) {
System.out.println("Esa matricula ya existe, ingrese otra matricula");
} else {
alumnos.put(m, new Alumno(n, m, d));
System.out.println("Se han dado de alta los datos :)");
System.out.println("Desea ingresar mas alumnos? \n");
String s = y.next();
//if (s.compareTo("si")==0 || s.compareTo("no")==0)
// b = true;
}
return alumnos;
}
public boolean consultas(Map alumnos) {
Scanner y = new Scanner(System.in);
boolean c;
System.out.println("Introduzca la matricula del estudiante a buscar");
int k = y.nextInt();
c = alumnos.containsKey(k);
if (c) {
System.out.println("Los datos son:\n" +"Nombre del alumno: "+ alumnos.get(k) + "Calificaciones: " + alumnos.values());
//System.out.println("Los datos son:\n" +"Nombre del alumno: "+ alumnos.get(k).getNombre() + "Calificaciones: " + al.getCalif());
} else {
System.out.println("El alumno no se encuentra");
}
return true;
}
The following program does not mark compilation errors but only the methods work for it darDeAlta(),darDeBaja(), the other methods consultas(),modificacion()do not work well because when I call them, the options menu appears: System.out.println("[a]ltas" + "\n" + "[b]ajas" + "\n" + "[c]onsultas" + "\n" + "[m]odificaciones" + "\n" + "[s]alir");
System.out.println("\n Seleccione una opcion");
and if I select any of these options again (m,c,s ), it shows me that menu again, that is, the code is cycled. Because?
How can I solve this problem?
class Alumno {
private String nombre;
private int matricula;
private double calificaciones[];
Alumno() {
}
Alumno(String nombre, int matricula, double calificaciones[]) {
this.calificaciones = calificaciones;
}
String getNombre() {
return nombre;
}
int getMat() {
return matricula;
}
double[] getCalif() {
return calificaciones;
}
void setCalif(double calif[]) {
calificaciones = calif;
}
}
public class Ejercicio{
Map<Integer, Alumno> alumnos = new TreeMap<>();
public boolean darDeAlta() {
Scanner y = new Scanner(System.in);
boolean b=false;
double d[] = new double[5];
System.out.println("Introduzca el nombre del estudiante");
String n = y.nextLine();
System.out.println("Introduzca su matricula (de 5 digitos)");
int m = y.nextInt();
System.out.println("Introduzca las calificaciones: \n");
for (int i = 0; i < 5; i++) {
System.out.println("Introduzca la calificacion");
d[i] = y.nextDouble();
}
if (alumnos.containsKey(m)) {
System.out.println("Esa matricula ya existe, ingrese otra matricula");
} else {
alumnos.put(m, new Alumno(n, m, d));
System.out.println("Se han dado de alta los datos :)");
System.out.println("Desea ingresar mas alumnos?");
String s = y.next();
if (s.compareTo("si")==0 || s.compareTo("no")==0)
b = true;
}
return b;
}
public boolean darDeBaja() {
Scanner y = new Scanner(System.in);
boolean c;
System.out.println("Introduzca la matricula del alumno");
int m = y.nextInt();
c = alumnos.containsKey(m);
if (c) {
alumnos.remove(m);
System.out.println("Se ha dado de baja al alumno");
} else {
System.out.println("No existe esa matricula");
}
return true;
}
public boolean consultas() {
Scanner y = new Scanner(System.in);
boolean c;
Alumno al = new Alumno();
System.out.println("Introduzca la matricula del estudiante a buscar");
int k = y.nextInt();
c = alumnos.containsKey(k);
if (c) {
System.out.println("Los datos son:\n" +"Nombre del alumno: "+ alumnos.get(k) + "Calificaciones: " + al.getCalif());
} else {
System.out.println("El alumno no se encuentra");
}
return true;
}
public boolean modificaciones() {
Scanner y = new Scanner(System.in);
boolean c;
Alumno al = new Alumno();
double calificacionesNvas[] = new double[5];
System.out.println("Introduzca la matricula del estudiante");
int k = y.nextInt();
c = alumnos.containsKey(k);
if (c) {
System.out.println("Cuales son las nuevas calificaciones? \n");
for (int i = 0; i < 4; i++) {
System.out.println("Introduzca la calificacion");
double calif = y.nextDouble();
calificacionesNvas[i] = calif;
}
al.setCalif(calificacionesNvas);
System.out.println("Se han modificado las calificaciones correctamente");
} else {
System.out.println("No existe esa matricula");
}
return true;
}
public static void main(String[] args) {
Scanner x = new Scanner(System.in);
boolean bandera = false;
Ejercicio e = new Ejercicio();
do {
System.out.println("[a]ltas" + "\n" + "[b]ajas" + "\n" + "[c]onsultas" + "\n" + "[m]odificaciones" + "\n" + "[s]alir");
System.out.println("\n Seleccione una opcion");
String opcion = x.next();
if (opcion.compareTo("a") == 0) {
bandera = e.darDeAlta();
}
if (opcion.compareTo("b") == 0) {
e.darDeBaja();
if (opcion.compareTo("c") == 0) {
e.consultas();
if (opcion.compareTo("m") == 0) {
e.modificaciones();
if (opcion.compareTo("s") == 0) {
bandera = false;
}
}
}
}
} while (bandera);
}
}
The following code does not flag compilation errors, but when I call the method darDeAlta()and enter data, it flags the following error:
Exception in thread "main" java.lang.NullPointerExceptionIn the line d[i] = y.nextDouble();(within the method) and in the line bandera = e.darDeAlta();(within the main), I already initialized the array of doubles with nulland I don't understand why it gives me that error.
public class Ejercicio {
Map<Integer, Alumno> alumnos = new TreeMap<>();
public boolean darDeAlta() {
Scanner y = new Scanner(System.in);
boolean b = false;
double d[] = null;
System.out.println("Introduzca el nombre del estudiante");
String n = y.nextLine();
System.out.println("Introduzca su matricula (de 5 digitos)");
int m = y.nextInt();
System.out.println("Introduzca las calificaciones: \n");
for (int i = 0; i < 5; i++) {
System.out.println("Introduzca la calificacion");
d[i] = y.nextDouble();//marca error aqui
}
if (alumnos.containsKey(m)) {
System.out.println("Esa matricula ya existe, ingrese otra matricula");
} else {
alumnos.put(m, new Alumno(n, m, d));
System.out.println("Se han dado de alta los datos :)");
System.out.println("Desea ingresar mas alumnos?");
String s = y.nextLine();
if (s.equals("si")) {
b = true;
} else {
b = false;
}
}
return b;
}
public static void main(String[] args) {
Scanner x = new Scanner(System.in);
boolean bandera = false;
Ejercicio e = new Ejercicio();
do {
System.out.println("[a]ltas" + "\n" + "[b]ajas" + "\n" + "[c]onsultas" + "\n" + "[m]odificaciones" + "\n" + "[s]alir");
System.out.println("\n Seleccione una opcion");
String opcion = x.next();
if (opcion.compareTo("a") == 0) {
bandera = e.darDeAlta();//marca error aqui
}
if (opcion.compareTo("b") == 0) {
e.darDeBaja();
if (opcion.compareTo("c") == 0) {
e.consultas();
if (opcion.compareTo("m") == 0) {
e.modificaciones();
if (opcion.compareTo("s") == 0) {
bandera = false;
}
}
}
}
} while (bandera);
}
}
I have solved the following exercise but I have a problem, I don't know how to differentiate the possible values that a key of a TreeMap represents in the following code, for example in the method darDeBajaI have to look for a keyand if that keyhas at least 2 values assigned, I have to analyze which of the 2 values works for me; How can I know how many values are assigned to that key?
Exercise: Do the following problem using Map and TreeMap.
You have the information of a student (name, registration number -key of 5 whole digits-, final grades of 5 subjects). This information must be defined in a class and must be private attributes. Make a program that has the following menu:
[high]
[low
[c]onsults
[modifications
[leave
Each of the following options will have you perform the following tasks:
high . The data of a student will be registered, if you want to enter more, you must return to the menu. A message must be sent confirming the registration of data. you go down A student will be dropped from enrollment (and name if necessary). A message must be sent confirming the withdrawal of the student, as well as the error if it cannot be done. Consultations. Only the data of the student to be searched will be displayed, their enrollment (and name if necessary), if the student is not found, indicate it with a message. Modifications. From the registration (and the name if necessary) of the student, some of the qualifications can be modified. A message should be sent confirming the successful modification no.
Leave. The program will end.
class Alumnado {
private String nombre;
private int matricula;
private double calificaciones[];
Map<Integer, String> datos = new TreeMap<>();
Alumnado() {
}
Alumnado(String nombre, int matricula, double calificaciones[]) {
datos.put(matricula, nombre);
this.calificaciones = calificaciones;
}
String getNombre() {
return nombre;
}
int getMat() {
return matricula;
}
double[] getCalif() {
return calificaciones;
}
void setCalif(double calif[]) {
calificaciones = calif;
}
}
public class Ejercicio {
public static boolean darDeAlta() {
Scanner y = new Scanner(System.in);
boolean b;
double d[] = null;
Alumnado alum;
System.out.println("Introduzca el nombre del estudiante");
String n = y.nextLine();
System.out.println("Introduzca su matricula (de 5 digitos)");
int m = y.nextInt();
System.out.println("Introduzca las calificaciones \n");
for (int i = 0; i < 5; i++) {
System.out.println("Introduzca la calificacion");
d[i] = y.nextDouble();
}
alum = new Alumnado(n, m, d);
System.out.println("Se han dado de alta los datos :)");
System.out.println("Desea ingresar mas alumnos?");
String s = y.nextLine();
if (s.equals("si")) {
b = true;
} else {
b = false;
}
return b;
}
public static void darDeBaja(String b) {
Scanner y = new Scanner(System.in);
boolean c;
Alumnado al = new Alumnado();
System.out.println("Introduzca la matricula del alumno");
int m = y.nextInt();
c = al.datos.containsKey(m);
if (c) {
al.datos.remove(m);
System.out.println("Se ha dado de baja al alumno");
} else {
System.out.println("No existe esa matricula");
}
}
public static void consultas() {
Scanner y = new Scanner(System.in);
boolean c;
Alumnado al = new Alumnado();
System.out.println("Introduzca la matricula del estudiante a
buscar");
int k = y.nextInt();
c = al.datos.containsKey(k);
if (c) {
System.out.println("Los datos son:" + al.datos.get(k) + " " +
al.getCalif());
} else {
System.out.println("El alumno no se encuentra");
}
}
public static void modificaciones() {
Scanner y = new Scanner(System.in);
boolean c;
Alumnado al = new Alumnado();
System.out.println("Introduzca la matricula del estudiante");
int k = y.nextInt();
c = al.datos.containsKey(k);
if (c) {
double calificacionNva[] = null;
System.out.println("Cuales son las nuevas calificaciones?");
for (int i = 0; i < 4; i++) {
double calif = y.nextDouble();
calificacionNva[i] = calif;
}
al.setCalif(calificacionNva);
System.out.println("Se han modificado las calificaciones
correctamente");
} else {
System.out.println("No existe esa matricula");
}
}
public static void main(String[] args) {
Scanner x = new Scanner(System.in);
boolean bandera;
if (bandera = true) {
System.out.println("[a]ltas" + "\n" + "[b]ajas" + "\n" + "
[c]onsultas" + "\n" + "[m]odificaciones" + "\n" + "[s]alir");
System.out.println("\n Seleccione una opcion");
String opcion = x.next();
if (opcion.compareTo("a") == 0) {
bandera = darDeAlta();
}
if (opcion.compareTo("b") == 0) {
darDeBaja("b");
if (opcion.compareTo("c") == 0) {
consultas();
if (opcion.compareTo("m") == 0) {
modificaciones();
if (opcion.compareTo("s") == 0) {
bandera = false;
}
}
}
}
}
}
}
Note: The exercise is already solved :), although it fails in the darDeAlta.. method.
Any suggestion/help is welcome/appreciated.
This does not return anything to me: System.out.println(tree.values());, the castings do not work either, ie System.out.println((int)tree.values());
How do I get it to print the collection of key values?
Map<Integer,String> tree=new TreeMap<>();
tree.values();//Devuelve una colección de los valores contenidos en
//este mapa.
System.out.println(tree.values());
In the following class I have the method getName()which I wanted it to be staticbecause I was going to use it inside another method in the same class Person(I wanted to do this: Person.getName()), however when I put it I staticgot the following error:
non-static variable name cannot be referenced from a static context, a possible solution would be to remove the privateto variable name,
is there any other solution for this problem?
Could privatethe variable be preserved name?
class Person{
private String name, gender;
Person(String name, String gender){
this.name=name;
this.gender=gender;
}
static String getName(){//si se le pone static marca error.
return name;
}
String getGender(){
return gender;
}
}
In the method queueAnalysis, when I command to print System.out.println("Original: " + queue + "\n");, System.out.println("colados: " + names + "\n");and
System.out.println("Cola final: " +queue);, it gives me as output direcciones de memoria, nulland direcciones de memoria, I already tried to apply a iteratorand apply a class type casting Customerbut even so it continues to give memory addresses as output. Why?,
How can I fix the problem?
class Customer {
String name;
int ticket;
Customer(String name, int ticket) {
this.name = name;
this.ticket = ticket;
}
String getName() {
return name;
}
int getTicket() {
return ticket;
}
}
public class Main {
public static void main(String[] args) {
Queue<Customer> queue = new LinkedList<>();
queue.add(new Customer("a1", 1));
queue.add(new Customer("a2", 2));
queue.add(new Customer("a3", -1));
queue.add(new Customer("a4", -1));
queueAnalysis(queue);
}
public static void queueAnalysis(Queue<Customer> queue) {
System.out.println("Original: " + queue + "\n");
String names[] = null;
int cant = 0;
int tam = queue.size();
for (int i = 0; i < tam; i++) {
if (queue.peek().getTicket() == -1) {
names[i] = queue.peek().getName();
cant++;
queue.poll();
}
}
System.out.println("colados: " + names + "\n");
System.out.println("Cola final: " +queue);
//Customer c;
for (Iterator it = queue.iterator(); it.hasNext();) {
System.out.println((Customer) it.next());
}
}
}
When executing this code I get an error:
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 1, Size: 0
So in a stack you can never add objects from position n, n=1,2,..., infinity, it will always start at position 0??
My idea was to pila.add("(");put it in position 0.
public static void main(String[] args){
LinkedList<String> pila=new LinkedList<>();
pila.add(1,"1");
pila.add(2,"2");
pila.add(3,"3");
pila.add(4,"*");
pila.add("(");
System.out.println(pila);
}
I have to do this declaration String op = tokens.next();inside the loop while
, if I put it outside the loop, ie String op=null; while{...op=tokens.next();...}I get an error that says: The assigned value is never used, but it is a contradiction because I do use it inside the while.
Then on other occasions it requires that the declaration be outside the loop, such as in loops for.
public static int postfixEvaluate(String exp) {
Stack<Integer> s = new Stack<Integer> ();
Scanner tokens = new Scanner(exp);
//String op =null;
while (tokens.hasNext()) {
if (tokens.hasNextInt())
s.push(tokens.nextInt());
else {
int num2 = s.pop();
int num1 = s.pop();
String op = tokens.next();
if (op.equals("+"))
s.push(num1 + num2);
else {
if (op.equals("-"))
s.push(num1 - num2);
else{
if (op.equals("*"))
s.push(num1 * num2);
else
s.push(num1 / num2);
}
}}}
return s.pop();
}}
We have List<Integer> lista=new Arraylist<>();where list is of size n and in each position it has an integer, that is, lista.get(0)==2,lista.get(1)==8...,lista.get(n)==6.
And I would like to multiply an integer, say k , by the entire number that makes up the list, ie k *(28...6).
How could I do it?
Exercise: Read an arithmetic expression grouped by parentheses and verify if it is syntactically well formed.
Consider:
1. Parentheses close and open correctly, there are pairs of them.
2. Letters should be used as literals (upper or lower case).
3.Review the proper use of operators (which need two operands).
4. Parentheses properly open and close expressions: (a + b) and not (a + ) b.
I already wrote the code, and the only problem I have is that when I give it as input: a+()it gives as output: La expresion esta escrita de manera correcta, but it is incorrect, how could I solve the problem ?
Note: The code compiles fine.
public class Prueba {
public static void main(String[] args) {
Scanner x = new Scanner(System.in);
System.out.println("De que tamaño sera su expresion?");
int n = x.nextInt();
LinkedList pila = new LinkedList();
LinkedList pila2 = new LinkedList();
LinkedList pila3 = new LinkedList();
LinkedList pp = new LinkedList();
LinkedList ppo = new LinkedList();
LinkedList pilaC = new LinkedList();
for (int i = 0; i < n; i++) {
System.out.println("Introduzca su elemento");
x.nextLine();
String e = x.nextLine();
pila.push(e);
pila2.push(e);
pila3.push(e);
}
int a = 0, b = 0;
while (!pila.isEmpty()) {
String element = (String) pila.pop();
if ((0 == element.compareTo(")")||0 == element.compareTo("("))
&& !pila.isEmpty()) {
String sim = (String) pila.pop();
if (0 == sim.compareTo("+") || 0 == sim.compareTo("-") || 0
== sim.compareTo("*") || 0 == sim.compareTo("/")) {
a++;
}
}
}
if (a != 0) {
System.out.println("La expresion no esta escrita de manera"+
"correcta");
} else {
while (!pila2.isEmpty()) {
String simbolo = (String) pila2.pop();
if ((0 == simbolo.compareTo("+") || 0 ==
simbolo.compareTo("-") || 0 == simbolo.compareTo("*") || 0 ==
simbolo.compareTo("/")) && !pila2.isEmpty()) {
String el = (String) pila2.pop();
if (0 == el.compareTo("(")||0 == el.compareTo(")") || 0
== el.compareTo("+") || 0 == el.compareTo("-") || 0 ==
el.compareTo("*") || 0 == el.compareTo("/")) {
b++;
}
}
}
if (b != 0) {
System.out.println("La expresion no esta escrita de manera"
+ "correcta :/");
} else {
while (!pila3.isEmpty()) {
String e = (String) pila3.pop();
if (0 == e.compareTo("(") || 0 == e.compareTo(")")) {
pp.push(e);
}
}
while (!pp.isEmpty()) {
ppo.push(pp.pop());
}
int w=0;
while(!ppo.isEmpty() && w!=1){
String s=(String)ppo.pop();
if(0==s.compareTo("(") && !pilaC.isEmpty())
pilaC.pop();
else{
if(0==s.compareTo("(") && pilaC.isEmpty()){
System.out.println("La expresion no esta"+
"escrita de manera correcta ");
w=1;
}
else
pilaC.push(s);
}
}
if(w==1)
System.out.println();
else
{
if(!pilaC.isEmpty())
System.out.println("La expresion no esta escrita de"+
"manera correcta ");
else
System.out.println("La expresion esta escrita de"+
"manera correcta :)");
}
}
}
}
}
I have a question about the following code, the idea is that if given as input:
a + b + c + d + ... + z
Gives as output:
correct expression
If given as input:
a + b + c ++ b + b b...z
Gives as output:
wrong expression
The program works fine if it is given:
a+b
But there is an error when I enter it
a+b+c+d
Well, it gives me as output:
incorrect expression
When it is correct.
public class Ejercicio5sep {
public static void main(String[] args) {
Scanner x = new Scanner(System.in);
LinkedList pila = new LinkedList();
int correcto = 0;
System.out.println("Cuantos elementos quiere introducirle a la pila?");
int n = x.nextInt();
for (int i = 0; i < n; i++) {
System.out.println("introduzca su elemento");
String e = x.next();
pila.push(e);
}
if (pila.size() % 2 != 0) {
float d = (float) pila.size() / 2f + 0.5f;
for (int i = 0; i < pila.size() / 2; i++) {
String a = (String) pila.pop();
String b = (String) pila.pop();
if (false == a.equals("+") && b.equals("+")) {
correcto++;
}
}
String c = (String) pila.pop();
if (false == c.equals("+"))//(*)
{
correcto++;
}
//si input: a+b+c+d
System.out.println(correcto);//dice que correcto==2, entonces
//no hizo la instruccion (*), ?porque
if (correcto == d) {
System.out.println("La expresion es correta");
} else {
System.out.println("La expresion no es correta");
}
} else {
System.out.println("expresion incorrecta :(");
}
That is, if I put as input in the method duracionTotalCD: the 2nd title of the CD , it gives me as output: the duration of the 2nd song of the 2nd CD , and it should return as output: the sum of the 2 songs of the 2nd CD .
NOTE: The program does not mark any compilation errors, simply the methods do not return what they have to return.
class CD {
private String titulo, autor;
List<Cancion> listaCanss = new ArrayList<Cancion>();
CD(String titulo, String autor, List<Cancion> listaCans) {
this.autor = autor;
this.listaCanss = listaCans;
this.titulo = titulo;
}
String getTitulo() {
return titulo;
}
void setTitulo(String titulo) {
this.titulo = titulo;
}
List<Cancion> getlistaCans() {
return listaCanss;
}
void setlistaCans(List<Cancion> s) {
listaCanss = s;
}
String getAutor() {
return autor;
}
void setAutor(String autor) {
this.autor = autor;
}
class Cancion {
private String titulo;
private double duracion;
Cancion(String titulo, double duracion) {
this.titulo = titulo;
this.duracion = duracion;
}
double getDuracion() {
return duracion;
}
void setDuracion(double d) {
duracion = d;
}
public String getTituloC() {
return titulo;
}
void setTituloC(String d) {
titulo = d;
}
}
public class Ejercicio {
public static void main(String[] args) {
Scanner leer = new Scanner(System.in);
List<CD> listaCDs = new ArrayList<CD>(3);
List<Cancion> listaCanss = new ArrayList<Cancion>(2);
for (int i = 0; i < 3; i++) {
System.out.println("Nombre CD:");
String nomCD = leer.nextLine();
System.out.println("Autor CD:");
String aut = leer.nextLine();
leer.nextLine();
for (int j = 0; j < 2; j++) {
System.out.println("Nombre cancion:");
String nomCan = leer.nextLine();
System.out.println("duracion cancion:");
double dur = leer.nextInt();
leer.nextLine();
listaCanss.add(new Cancion(nomCan, dur));
}
listaCDs.add(new CD(nomCD, aut, listaCanss));
}
System.out.println("Introduzca el titulo del CD para devolver su
duracion total");
leer.nextLine();
String stt = leer.nextLine();
System.out.println(duracionTotalCD(stt, listaCDs));
System.out.println("Introduzca el nombre de la cancion a buscar
para devolver el CD al que pertenece y su respectivo autor");
leer.nextLine();
String st = leer.nextLine();
System.out.println(TitAu(listaCDs, st));
}
static double duracionTotalCD(String titulo, List<CD> listaCDs) {
double duracionT = 0;
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 2; j++) {
if (0 == (listaCDs.get(i).getTitulo()).compareTo(titulo)) {
duracionT = duracionT +
listaCDs.get(i).listaCanss.get(j).getDuracion();
}
}
}
return duracionT;
}
public static String TitAu(List<CD> c, String n) {
int tam = c.size();
String s1 = null, s2 = null;
for (int i = 0; i < tam; i++) {
for (int j = 0; j < 2; j++) {
if ((c.get(i).listaCanss.get(j).getTituloC()).compareTo(n)
== 0) {
s1 = c.get(i).getTitulo() + " ";
s2 = c.get(i).getAutor();
}
}
}
return s1 + s2;
}
}
I have the following code and it turns out that when I run it, it executes first for (ListIterator it = pila1.listIterator(pila1.size()); it.hasPrevious();), then for (ListIterator itt = pila2.listIterator(pila2.size()); itt.hasPrevious();)and then the rest of the code, and then returns to for (ListIterator it = pila1.listIterator(pila1.size()); it.hasPrevious();), that is, it does not finish going through all the elements of the second cycle for, why?
Notes: The structure is for(alguna_declaracion; cuantas_veces_se_ejecutara;). The program works fine :)
public class ClaseEjercicio31ago {
public static void main(String[] args) {
Scanner leer = new Scanner(System.in);
List<Integer> pila1 = new ArrayList<Integer>();
List<Integer> pila2 = new ArrayList<Integer>();
List<Integer> cola = new ArrayList<Integer>();
System.out.println("Introduzca los digitos (5) para la pila1");
for (char digito : leer.nextLine().toCharArray()) {
pila1.add(digito - '0');
}
System.out.println("Introduzca los digitos (5) para la pila2");
for (char digito : leer.nextLine().toCharArray()) {
pila2.add(digito - '0');
}
int uno = 0;
for (ListIterator it = pila1.listIterator(pila1.size()); it.hasPrevious();) {
for (ListIterator itt = pila2.listIterator(pila2.size()); itt.hasPrevious();) {
int n1 = (Integer) it.previous();
int n2 = (Integer) itt.previous();
int n3 = (n1 + n2 + uno);
if (n3 >= 10) {
cola.add(n3 - 10);
uno = 1;
} else {
cola.add(n3 + uno);
}
it.remove();
itt.remove();
}
}
if (uno == 1) {
cola.add(1);
}
System.out.println("La suma de las pilas es:");
for (Iterator it = cola.iterator(); it.hasNext();) {
int t = (Integer) it.next();
System.out.print("\n " + t + "\n");
it.remove();
}
I have the following exercise:
In a port, moorings (parking space) for boats are rented. For each rental, the name, the client number, the number of days of rental, the position of the mooring and the boat that occupies it are stored. A boat is characterized by its registration, its Slovak (in meters) and the year of manufacture. The boats differ according to their type and characteristics in:
Sailboats: number of masts.
Sports boats: power in the engine.
Luxury yachts: engine power and number of cabins.
The rental cost is calculated by multiplying the number of days of occupation by the daily cost, which varies according to the type of boat:
For sailboats it is calculated by multiplying the number of masts by $15.
For boats it is calculated by multiplying the meters of Slovakia by $35.
For yachts it is calculated by multiplying the number of cabins by $17.
- Use inheritance to implement classes and their relationships.
Generate a test class that:
- Enter the information for each type of ship.
- Using polymorphism compute the rent paid by the customer.
- Using an interface displays the data for each of the ship types.
I have made the following code, but I have some questions. In principle I have to create a test class so that the user can enter information for each of the types of boats (sailboats, luxury yachts, boats) and I already entered that information, but not as expected.
I wanted to send all the information of the sailboat through the constructor of the class Renta, ie Renta(String nombre, String posicion, int numDias, int numCliente, Barco barco), but I don't know how to send it information through the attribute barco, so to solve the problem I created one interfaceso that I could store and print the data of the sailboat.
interface Adicional {
String muestraDatos();
double costoRenta();
}
class Renta implements Adicional {
private String nombre, posicion;
private int numDias, numCliente;
private Barco barco;
Renta() {
}
Renta(String nombre, String posicion, int numDias, int numCliente, Barco barco) {
this.nombre = nombre;
this.posicion = posicion;
this.numDias = numDias;
this.numCliente = numCliente;
this.barco = barco;
}
public String muestraDatos() {
return nombre + " " + posicion + " " + numDias + " " + numCliente + " " + barco;
}
public double costoRenta() {
return 0;
}
String getNombre() {
return nombre;
}
String getPosicion() {
return posicion;
}
int getNumDias() {
return numDias;
}
int getNumCliente() {
return numCliente;
}
Barco getBarco() {
return barco;
}
void setNombre(String n) {
nombre = n;
}
void setPosicion(String p) {
posicion = p;
}
void setNumDias(int n) {
numDias = n;
}
void setNumCliente(int n) {
numCliente = n;
}
void setBarco(Barco barco) {
this.barco = barco;
}
}
abstract class Barco {
private int matricula, year;
protected double eslova;//en metros
Barco(int matricula, int year, double eslova) {
this.matricula = matricula;
this.year = year;
this.eslova = eslova;//longitud del barco
}
public double costoRenta() {
return 0;
}
public String muestraDatos() {
return matricula + " " + year + " " + eslova + " ";
}
}
class Velero extends Barco {
private int numMastiles;
Velero(int matricula, int year, double eslova, int numMastiles) {
super(matricula, year, eslova);
this.numMastiles = numMastiles;
}
public String muestraDatos() {
return super.muestraDatos() + " " + numMastiles;
}
public double costoRenta() {
return 15 * numMastiles;
}
}
abstract class BoteConMotor extends Barco {
protected double potenciaMotor;
BoteConMotor(int matricula, int year, double eslova, double potenciaMotor) {
super(matricula, year, eslova);
this.potenciaMotor = potenciaMotor;
}
public String muestraDatos() {
return super.muestraDatos() + " " + potenciaMotor;
}
}
class Embarcaciones extends BoteConMotor {
Embarcaciones(int matricula, int year, double eslova, double potenciaMotor) {
super(matricula, year, eslova, potenciaMotor);
}
public double costoRenta() {
return 35 * eslova;
}
}
class YateLujo extends BoteConMotor {
private int numCamarotes;
YateLujo(int matricula, int year, double eslova, double potenciaMotor, int numCamarotes) {
super(matricula, year, eslova, potenciaMotor);
this.numCamarotes = numCamarotes;
}
public String muestraDatos() {
return super.muestraDatos() + " " + numCamarotes;
}
public double costoRenta() {
return numCamarotes * 17;
}
}
public class AlquilacionBARCOS {
public static void main(String[] args) {
Scanner r = new Scanner(System.in);
Renta s = new Renta();
Barco b[] = new Barco[3];
System.out.println("Introduzca la informacion para el barco velero\n");
System.out.println("nombre del cliente");
String nam = r.nextLine();
s.setNombre(nam);
System.out.println("num. de cliente");
int n = r.nextInt();
s.setNumCliente(n);
System.out.println("num. de dias de renta");
int m = r.nextInt();
s.setNumDias(m);
System.out.println("posicion de amarre");
r.nextLine();
String p = r.nextLine();
s.setPosicion(p);
System.out.println("matricula:");
int q = r.nextInt();
System.out.println("eslova:");
double w = r.nextDouble();
System.out.println("year de fabricacion:");
int k = r.nextInt();
System.out.println("num. de mastiles:");
int v = r.nextInt();
b[0] = new Velero(q, k, w, v);
System.out.println(b[0].muestraDatos() + " " + b[0].costoRenta()+" "+s.muestraDatos());
}
}
My question is: how to send all the information about some type of ship using this constructor Renta(String nombre, String posicion, int numDias, int numCliente, Barco barco)?
What is the difference, advantages, disadvantages between:
List a=new ArrayList();\\suponiendo que introducire numeros enterosArrayList a=new ArrayList(); \\suponiendo que introducire numeros enterosArrayList<Integer> a=new ArrayList<Integer>();List <Integer> a=new ArrayList<Integer>();Or are they all equivalent?
Note: instead of ArrayListcould also have been LinkedListor someone else.
How to read the for loop of the code? I guess it reads like this: For each digit of type read it charand convert it to a character array or maybe like this: For each digit of type charread it and add it to a character array?
System.out.println("Introduzca los digitos para la sucesion1");
for (char digito : q.nextLine().toCharArray()) {
seq1.add(digito - '0');
}
In general, after the 2 points, :any action/condition that the cycle has to do can go for? or are there restrictions for this different way of representing the cycle for?
I have a question about the following exercise, in the NOTE it says that duplicate elements are not allowed in the classes, and in the exercise solution, in 3 classes (classes: AutoLujo, AutoCompacto and Wagon) I put the same code (same methods and attributes) because I did not find another possible solution for the exercise, is there a way to correct the repeated code? Or is the solution fine now?
Exercise: A car dealership wants a computer system to manage its vehicle data and classify it by type. All cars have the following data:
Vehicles are categorized into compact cars, luxury cars, pickup trucks, and station wagons . For cars and vans, it is also important to store the number of passengers; while for trucks, the load capacity in kgs must be controlled. and the number of axles and tracks.
Model this system and instantiate each of the classes, assigning data through their respective properties. Add a parameterized constructor to each class to initialize its data and call the base class's constructor from each derived class's constructor (do not use default constructors). Implement the ToString() method override to display the data for each car type.
NOTE: Duplicate components in classes and empty classes (no elements) are not allowed.
interface Pasajeros
{
int getCantidadPasajeros();
void setCantidadPasajeros(int n);
}
class Auto
{
private int numSerieMotor,año;
private String marca;
private double precio;
Auto(){}
Auto(int numSerieMotor, int año, String marca,double precio)
{
this.numSerieMotor=numSerieMotor;
this.año=año;
this.marca=marca;
this.precio=precio;
}
public String toString()
{
return numSerieMotor+" "+ año+" "+marca+" "+ precio;
}
}
class AutoCompacto extends Auto implements Pasajeros
{ private int pasajeros;
AutoCompacto(int numSerieMotor, int año, String marca,double precio)
{
super(numSerieMotor,año,marca,precio);
}
AutoCompacto(){}
public String toString()
{
return super.toString()+" "+pasajeros;
}
public int getCantidadPasajeros()
{
return pasajeros;
}
public void setCantidadPasajeros(int n)
{
pasajeros=n;
}
}
class AutoLujo extends Auto implements Pasajeros
{ private int pasajeros;
AutoLujo(int numSerieMotor, int año, String marca,double precio)
{
super(numSerieMotor,año,marca,precio);
}
public String toString()
{
return super.toString()+" "+pasajeros;
}
public int getCantidadPasajeros()
{
return pasajeros;
}
public void setCantidadPasajeros(int n)
{
pasajeros=n;
}
}
class Camioneta extends Auto
{
private int capacidadCarga;
private int cantidadEjes;
private int cantidadRodadas;
Camioneta (int numSerieMotor, int año, String marca,double precio,int
capacidadCarga,int cantidadEjes,
int cantidadRodadas)
{
super(numSerieMotor,año,marca,precio);
this.capacidadCarga=capacidadCarga;
this.cantidadEjes=cantidadEjes;
this.cantidadRodadas=cantidadRodadas;
}
int getCarga()
{
return capacidadCarga;
}
int getEjes()
{
return cantidadEjes;
}
int getRodadas()
{
return cantidadRodadas;
}
void setCarga(int n)
{
capacidadCarga=n;
}
void setEjes(int n)
{
cantidadEjes=n;
}
void setRodadas(int n)
{
cantidadRodadas=n;
}
public String toString()
{
return super.toString()+" "+capacidadCarga+" "+cantidadEjes+"
"+cantidadRodadas;
}
}
class Vagon extends Auto implements Pasajeros
{ private int pasajeros;
Vagon(int numSerieMotor, int año, String marca,double precio)
{
super(numSerieMotor,año,marca,precio);
}
public String toString()
{
return super.toString()+" "+pasajeros;
}
public int getCantidadPasajeros(){
return pasajeros;
}
public void setCantidadPasajeros(int n)
{
pasajeros=n;
}
}
public class Tarea22ago
{
public static void main(String[] args)
{
Auto x[]=new Auto[4];
x[1]=new AutoCompacto();//analogo a AutoLujo();
Scanner s=new Scanner(System.in);
System.out.println("Introduzca los datos del auto de lujo:"+"\n");
System.out.println("Introduzca el numero de serie del motor");
int a=s.nextInt();
System.out.println("Introduzca la marca");
String b=s.next();
System.out.println("Introduzca el año");
int c=s.nextInt();
System.out.println("Introduzca el precio");
double d=s.nextDouble();
System.out.println("Introduzca la cantidad de pasajeros");
int e=s.nextInt();
x[0]=new AutoLujo(a,c,b,d);
((AutoLujo)x[0]).setCantidadPasajeros(e);
System.out.println(x[0].toString());//xq ponerle el s.o.p, si return
//ya regresa la cadena?
System.out.println("Introduzca los datos del vagon:"+"\n");
System.out.println("Introduzca el numero de serie del motor");
int f=s.nextInt();
System.out.println("Introduzca la marca");
String g=s.next();
System.out.println("Introduzca el año");
int h=s.nextInt();
System.out.println("Introduzca el precio");
double i=s.nextDouble();
System.out.println("Introduzca la cantidad de pasajeros");
int j=s.nextInt();
x[2]=new Vagon(f,h,g,i);
((Vagon)x[2]).setCantidadPasajeros(j);
System.out.println(x[2].toString());
System.out.println("Introduzca los datos de la camioneta:"+"\n");
System.out.println("Introduzca el numero de serie del motor");
int k=s.nextInt();
System.out.println("Introduzca la marca");
String l=s.next();
System.out.println("Introduzca el año");
int m=s.nextInt();
System.out.println("Introduzca el precio");
double n=s.nextDouble();
System.out.println("Introduzca la cantidad de carga");
int o=s.nextInt();
System.out.println("Introduzca la cantidad de ejes");
int p=s.nextInt();
System.out.println("Introduzca la cantidad de rodadas");
int q=s.nextInt();
x[3]=new Camioneta(k,m,l,n,o,p,q);
System.out.println(x[3].toString());
}
}
I have a question about the solution of the following exercise; in the main class, when I call the force() or telekinesis() methods (which are in the derived classes), I have to do several castings on a vector that declares the type of the parent class so that I can call those methods correctly, and my question is: Is there any other way to carry out what the program asks for?
Exercise: Generate a Java program that models, multiple inheritance and polymorphism the Metahuman superclass. From this class will be derived Hero and Villain. Each of them, whether hero or villain, can have at least two of the following powers: flight, speed, strength, weakness, hearing, telekinesis, telepathy; plus at least one own (unique) power. Model at least 2 heroes and 2 villains, who will fight using their powers. The user will enter the name of the hero or villain whose powers they want to know, either to save or destroy.
interface PoderParticular
{
String telequinesis();
String telepatia();
}
class Metahumano
{
String velocidad()
{
return "Tiene velocidad";
}
String debilidad()
{
return "Tiene debilidad";
}
String oir()
{
return "Tiene audicion";
}
}
class Heroe extends Metahumano implements PoderParticular
{
public String telepatia(){return "";}
String velocidad()
{
return "Tiene mucha velocidad";
}
String fuerza()
{
return "Tiene mucha fuerza";
}
public String telequinesis()
{
return ":-)";
}
}
class Villano extends Metahumano implements PoderParticular
{ public String telequinesis(){return "";}
public String telepatia()
{
return "Tiene nivel 1 en telepatia";
}
String volar()
{
return "Puede volar muy alto";
}
String debilidad()
{
return "Tiene poca debilidad";
}
}
public class EjercicioClase22ago {
public static void main(String[] args) {
Scanner leer=new Scanner(System.in);
Metahumano x[]=new Metahumano[4];
x[0]=new Heroe();
x[1]=new Villano();
System.out.println("Introduzca el nombre del heroe o del villano del
que desee saber cuales son sus superpoderes ya sea para salvar o
destruir");
String personaje=leer.next();
int n=personaje.compareTo("batman");
int k= personaje.compareTo("superman");
int l=personaje.compareTo("wason");
int m= personaje.compareTo("duende");
if (n==0 || k==0)
System.out.println(x[0].velocidad()+" "+((Heroe)x[0]).fuerza()+" "+((PoderParticular)x[0]).telequinesis());
else
if(l==0|| m==0)
System.out.println(((PoderParticular)x[1]).telepatia()+" "+((Villano)x[1]).volar()+" "+x[1].debilidad());
}
}