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mauricio
Asked: 2020-04-05 17:41:44 +0800 CST 2020-04-05 17:41:44 +0800 CST

Why doesn't it print the object information for me? [closed]

  • 772

It happens that I want to print this data on the screen, which is found in the tostring method.

public String tostring() {
    return "the weight is :"+ this.getWeight() +" and my age is :"+ this.getAge();
}

but it prints it this way

ejercicio2.Ejercicio2@15db9742

here the code with the set and get

public class Ejercicio2 {
private int weight;
private int age;

public int getWeight() {
    return weight;
}
public void setWeight(int weight) {
    this.weight = weight;
}
public int getAge() {
    return age;
}
public void setAge(int age) {
    this.age = age;
}

and the main class

public class Usoejercicio2 {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Ejercicio2 ob1 = new Ejercicio2();

    ob1.setAge(21);
    ob1.setWeight(55);

    System.out.println(ob1);

what am I doing wrong? yes please correct me

java

1 Answers

  1. Best Answer

    Why doesn't it print the object information for me?

    The problem lies in the way you have written the name of this method:

    public String tostring() {
    return "the weight is :"+ this.getWeight() +" and my age is :"+ this.getAge();
}

    If you had used the annotation @Override, the compiler would have given a compilation error and this is because tostring()it is not a method inherited from the class Object(base class of all classes in Java), therefore it cannot be overridden.

    Error example:

    class A 
{
    @Override 
    public String tostring() {
       return "the weight is :"+ this.getWeight() +" and my age is :"+ this.getAge();
    }
}

    When compiling it shows the following error:

    error: method does not override or implement a method from a supertype

    The error means that you cannot override the method because there is no base class that has it implemented.

    The method that all classes inherit (because by default they are subclasses of Object) is called toStringand not tostring. So the solution is to rename it:

    @Override
public String toString() {
    return "the weight is :"+ this.getWeight() +" and my age is :"+ this.getAge();
}

    And that's it, the program should launch the expected result.

    I also emphasize that this sentence:

    System.out.println(ob1);

    It is equivalent to:

    System.out.println(ob1.toString());

    The difference is that in the first statement, the Java compiler implicitly calls the method toString()and in the second we add it manually. So it doesn't matter which one you use, because both will give the same result.

    Conclusion:

    Use the annotation @Override, it saves headaches.

    • 2