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Martin Hope
bypabloc_
Asked: 2020-12-28 22:31:46 +0800 CST
  • 19

Since I use bootstrap, I looked for this style to make it more user-friendly, since I represent buttons with states trueand false.

I do it in the following way:

  $(function() {
    $('#toggle-event').change(function() {
      $('#console-event').html('Estado: ' + $(this).prop('checked'))
    })
  })
<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">


<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<link href="https://gitcdn.github.io/bootstrap-toggle/2.2.2/css/bootstrap-toggle.min.css" rel="stylesheet">
<script src="https://gitcdn.github.io/bootstrap-toggle/2.2.2/js/bootstrap-toggle.min.js"></script>

<input type="checkbox" id="toggle-event" checked data-toggle="toggle" data-on="Activo" data-off="Inactivo" data-onstyle="success" data-offstyle="danger">
<div id="console-event">Estado: true</div>

<!-- Latest compiled and minified JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>

I would like it to have a third state, which is null. There's a possibility? Or if there is another tool that gives me that option, welcome the suggestion.

javascript
Martin Hope
user13558
Asked: 2020-11-28 14:07:48 +0800 CST
  • 19

I would need to know how to read a character by keyboard in Java .

I know that you can read a number, or a phrase, but this time I would like it to read only one character, and the system to show a message, immediately after pressing that character, and not when I touch Intro.

The following code receives an integer, then I hit Intro, and it saves.

Scanner teclado = new Scanner(System.in);
int número = teclado.nextInt();

But what I want is to save a character without pressing the key. It's possible?

java
Martin Hope
Roy
Asked: 2020-10-24 08:20:32 +0800 CST
  • 19

As the title says, I want to limit the number of decimals that result from an operation with variables of type double, this result is displayed in a JTextArea of ​​a JFrame.

The code that does the operation and prints the result in the JTextArea is as follows: ( la, lband lcrepresent the sides of a triangle, acalculates the area and Ais the JTextArea where the result is printed).

if (lb+lc>la && la+lc>lb && la+lb>lc){
     a=Math.sqrt((la+lb+lc)*(-la+lb+lc)*(la-lb+lc)*(la+lb-lc)/16);
     p=la+lb+lc;
     A.setText("El triangulo es "+t+".\nEl area es ("+a+").\nEl perimetro es ("+p+").");
java
Martin Hope
Alvaro Montoro
Asked: 2020-07-14 06:30:53 +0800 CST
  • 19

I'm using HTML and CSS to learn/practice 2D and 3D transformations and for this I'm drawing a 3D 9v stack (because it's simple and square). So far everything has been easy because I have only needed transformations to rotate and move the different (rectangular) faces of the stack.

But I find that the electrodes in the cell are circular and I don't know how to make one div(or another) element circular (3D tube). I imagine it would be to "simulate" a circle using lots of vertices, but that seems tricky.

This is what I've got so far (on JSFiddle ):

@-moz-keyframes spin {
  from {transform:rotateY(0deg) rotateX(0) rotateZ(0);}
  to {transform:rotateY(360deg) rotateX(360deg) rotateZ(360deg);}
}
@-webkit-keyframes spin {
  from {transform:rotateY(0deg) rotateX(0) rotateZ(0);}
  to {transform:rotateY(360deg) rotateX(360deg) rotateZ(360deg);}
}
@keyframes spin {
  from {transform:rotateY(0deg) rotateX(0) rotateZ(360);}
  to {transform:rotateY(360deg) rotateX(360deg) rotateZ(0deg);}
}

.container {
  -webkit-perspective: 1000px;
  perspective: 1000px;
  position:relative;
  width:120px;
  height:200px;
  margin:100px;
}
#battery {
  width: 100%;
  height: 100%;
  position: absolute;
  transform-style: preserve-3d;
  -webkit-animation: spin 14s infinite linear;
  -moz-animation: spin 14s infinite linear;
  animation: spin 14s infinite linear;
}
.face {
  position:absolute;
  top:0;
  left:0;
  transform-origin:0 0;
  opacity:10.6;
  overflow:hidden;
}
.face:before, .face:after, .face span:after, .face span:before {
  position:absolute;
  top:0;
  left:0;
  transform-origin: left top 0;
  display:block;
  font-family:arial,sans-serif;
  white-space: pre;
}
.large {
  width:120px;
  height:200px;
  background:#111111;
  box-sizing:border-box;
  box-shadow:inset 0px 66px 0px #CC7722;
}
.side {
  width:66px;
  height:200px;
  background:black;
  box-sizing:border-box;
  box-shadow:inset 0px 66px 0px #AA5500;
}
.short {
  width:120px;
  height:66px;
  background:#222222;
}
.top {
  box-shadow:inset 0 0 0 8px #BB6611;
}
.bottom {
  box-shadow:inset 0 0 0 8px #111111;
}
.front:before, .back:before, .right:before {
  content:"DURACELL";
  color:silver;
  transform: rotate(90deg) translate(72px, -68px);
  font-weight:bold;
  font-size:1.3em;
}
.front:after, .back:after {
  content:"ALKALINE BATTERY";
  color:silver;
  transform: rotate(90deg) translate(73px, -44px);
  font-weight:bold;
  font-size:0.5em;
}
.back:after { content:"PILE ALCALINE"; }
.right:before { transform: rotate(90deg) translate(72px, -50px) }
.right:after {
  content:"Duracell, div of P&G, Bethel, CT 06801 \a P&G Inc., Toronto, ON M5W1C5 \a Made in U.S.A. / Fabrique aux E.-U. \a 95756099";
  width:130px;
  color:silver;
  transform: rotate(90deg) translate(73px, -27px);
  font-weight:bold;
  font-size:0.29em;
  letter-spacing:-0.1px;
  line-height:1.2em;
}
.right span:before {
  content:"\2b06\a+";
  font-weight:bold;
  line-height:0.8em;
  top:20px;
  left:20px;
  font-size:1.3em;
}
.right span:after {
  content:"MAR \a 2015";
  color:#AA5500;
  transform: rotate(90deg) translate(150px, -23px);
  width:60px;
  font-weight:bold;
  font-size:0.6em;
  text-align:center;
}
.left:before {
  content:"MN1604 \a 6LR61 \a 9 VOLTS";
  line-height:1em;
  transform: rotate(90deg) translate(15px, -59px);
  font-size:0.5em;
  font-weight:bold;
  letter-spacing:-0.1px;
}
.left span:before {
  content:"Caution: do not connect improperly. Charge or dispose of in fire. Battery may explode or leak. Do not carry batteries loose in your pocket or elsewhere as burn injury could result.";
  width:120px;
  color:silver;
  transform: rotate(90deg) translate(73px, -60px);
  font-weight:200;
  font-size:0.25em;
  letter-spacing:-0.2px;
  line-height:1.2em;
  text-transform:uppercase;
  white-space: normal;
}

#battery .front { transform: rotateY( 0deg ) translateZ( 66px ); }
#battery .back { transform: rotateY( 180deg ) translateX( -120px ); }
#battery .right { transform: rotateY( 90deg ) translateZ( 120px ) translateX(-66px); }
#battery .left { transform: rotateY( -90deg ) translateZ( 0 ); }
#battery .top { transform: rotateX( -270deg ) translateZ( 0 ); }
#battery .bottom { transform: rotateX( 90deg ) translateZ( -200px ); }
<div class="container">
  <div id="battery">
    <div class="face large front"></div>
    <div class="face large back"></div>
    <div class="face side right"><span></span></div>
    <div class="face side left"><span></span></div>
    <div class="face short top"></div>
    <div class="face short bottom"></div>
  </div>
</div>

and this is how it looks:

Battery in HTML + CSS, the electrodes are missing

I imagine it could be done with SVG or a canvas, but I want to limit myself to HTML+CSS3 (with 2D and 3D transformations). So my questions really are:

  • Can you have a divcurve? ( not a circle, but a tube )
  • Can they be divcurved? (eg to create two semicircles and join them in a circle)

And if the element cannot be curved, what could be an alternative? Or is my only option to simulate it as I was saying before?

html
Martin Hope
Anonymous Coward
Asked: 2020-01-02 01:14:55 +0800 CST
  • 19

I need to check that a date entered in a form is valid.

I have the date separated into year, day and month. And I'm not interested in checking dates before 1900.

I am doing it with this code: 

public class Fecha
{
    int año;
    int mes; // 1 a 12
    int dia; // 1 a 31
}

static int[] diasMes= {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
/**
 *   Comprueba si la fecha es correcta. Se comprueban solo fechas de 1900 
 * o posteriores.
 * @param fecha La fecha a comprobar.
 * @return true si la fecha es correcta, false en otro caso.
 * @throws IllegalArgumentException si el año es menor que 1900.
 */
boolean validaFecha( Fecha fecha)
{
    if ( fecha.año < 1900 ) {
        throw new IllegalArgumentException( 
                "Solo se comprueban fechas del año 1900 o posterior");
    }
    if ( fecha.mes<1 || fecha.mes>12 )
        return false;
    // Para febrero y bisiesto el limite es 29
    if ( fecha.mes==2 && fecha.año%4==0 )
        return fecha.dia>=1 && fecha.dia<=29;
    return fecha.dia>=0 && fecha.dia<=diasMes[fecha.mes-1];
}

The class FechaI use is somewhat more complicated, it has its setter, getter and other things, but those details are irrelevant to this question. The question is about the method validaFecha.

Is the implementation correct? Is there a way to do it with the standard libraries?

java
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