Java 如何使widgetviewer中的Jbutton实现正确的事件_Java_Swing_Widget_Jbutton_Numberformatexception

Java 如何使widgetviewer中的Jbutton实现正确的事件

java swing

Java 如何使widgetviewer中的Jbutton实现正确的事件,java,swing,widget,jbutton,numberformatexception,Java,Swing,Widget,Jbutton,Numberformatexception,说明： Write a WidgetViewer GUI that has the following widgets: a button labeled "go up/down" a label initialized to 0 (we'll call this the left label) a label initialized to 0 (we'll call this the right label) a button labeled "go down/up" When the "

说明：

Write a WidgetViewer GUI that has the following widgets:

a button labeled "go up/down"
a label initialized to 0 (we'll call this the left label)
a label initialized to 0 (we'll call this the right label)
a button labeled "go down/up"

When the "go up/down" button is pushed, a random number between 1 and 10 (inclusive)
is generated and added to the left label, and another random number between 1 and 10 (inclusive)
is generated and subtracted from the right label.

When the "go down/up" button is pushed, a random number between 1 and 10 (inclusive) is
generated and subtracted from the left label, and another random number between 1 and 10
(inclusive) is generated and added to the right label.

错误消息：

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "Go up/down"

代码：

我似乎无法理解此错误消息，可能是我添加了字符串，但我不确定，这可能是我的逻辑。但是我想弄清楚如何让名为goupdown和godownup的Jbutton显示一个随机数，然后根据需要加1或减1

public class UpAndDown {


    public UpAndDown() {

    WidgetViewer wv = new WidgetViewer();
    JButton goUpDown = new JButton("Go up/down");
    JLabel leftLabel = new JLabel("0");
    wv.add(goUpDown, 10, 30, 150, 20);
    wv.add(leftLabel, 10, 60, 150, 25);

    JButton goDownUp = new JButton("Go down/up");
    JLabel rightLabel = new JLabel("0");
    wv.add(goDownUp, 10, 120, 150, 20);
    wv.add(rightLabel, 10, 160, 150, 25);

    ButtonIncrement action = new ButtonIncrement(goUpDown);
    goUpDown.addActionListener(action);

    ButtonIncrement action2 = new ButtonIncrement(goDownUp);
    goDownUp.addActionListener(action2);
}

static class ButtonIncrement implements ActionListener {

    private final JButton goUpDownBtn;
    private final JButton goDownUpBtn;

    public ButtonIncrement(JButton buttonToModify) {
        goUpDownBtn = buttonToModify;
        goDownUpBtn = buttonToModify;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        int rand = (int) (Math.random() * 10);
        String val = goUpDownBtn.getText();
        //JButton jc = (JButton) e.getSource();
        int newVal = Integer.parseInt(val) + rand;
        goDownUpBtn.setText(String.valueOf(newVal));
        //jc.setText(goDownUpBtn.getText() + " " + val);// get string, convert to int, add rand value. then convert int back to string and set text to string

        /*String val2 = goDownUpBtn.getText();
        int newVal2 = Integer.parseInt(val2) + rand;
        goDownUpBtn.setText(String.valueOf(newVal2));*/


    }
}

编写具有以下小部件的WidgetViewer GUI：

标签为“向上/向下”的按钮初始化为0的标签（我们将调用这是左标签）初始化为0的标签（我们称之为右标签）标签为“向下/向上”的按钮

按下“向上/向下”按钮时，会出现一个介于1和之间的随机数生成10（包括），并将其添加到左侧标签，以及另一个生成并减去介于1和10（含）之间的随机数从右边的标签

按下“向下/向上”按钮时，会出现一个介于1和之间的随机数生成10（含），并从左标签中减去，以及生成另一个介于1和10（含）之间的随机数，然后添加到正确的标签

所以，我们需要从中吸取一些重要的东西

这些值最初初始化为0
当按钮被触发时，您需要更新标签
根据触发的按钮，将确定要添加或减去的值

因此，我们可以简单地从

class IncrementDecrementAction implements ActionListener {

    private final JLabel leftLabel;
    private final JLabel rightLabel;

    private int leftValue = 0;
    private int rightValue = 0;

    public IncrementDecrementAction(JLabel leftLabel, JLabel rightLabel) {
        this.leftLabel = leftLabel;
        this.rightLabel = rightLabel;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        int rand = (int) (Math.random() * 10) + 1;
        leftValue += rand;
        rand = (int) (Math.random() * 10) + 1;
        rightValue += rand;
        this.leftLabel.setText(Integer.toString(leftValue));
        this.rightLabel.setText(Integer.toString(rightValue));
    }
}

好的，但这只解决了一个方向的问题，那么向下/向上呢

我们可以编写第二个

ActionListener

来处理这个问题，但是你需要某种模型来维护左右值，这样两个监听器都知道当前值是什么。这不是一个不合理的想法，但它需要额外的两个类来实现

相反，我们可以利用

ActionEvent

的

actionCommand

支持，为每个按钮指定一个特定的名称，我们可以在触发操作时查找该名称

class IncrementDecrementAction implements ActionListener {

    private final JLabel leftLabel;
    private final JLabel rightLabel;

    private int leftValue = 0;
    private int rightValue = 0;

    public IncrementDecrementAction(JLabel leftLabel, JLabel rightLabel) {
        this.leftLabel = leftLabel;
        this.rightLabel = rightLabel;
    }

    @Override
    public void actionPerformed(ActionEvent e) {

        int leftRandom = (int) (Math.random() * 10) + 1;
        int rightRandom = (int) (Math.random() * 10) + 1;
        if (e.getActionCommand().equals("upDown")) {
            leftValue += leftRandom;
            rightValue -= rightRandom;
        } else if (e.getActionCommand().equals("downUp")) {
            leftValue -= leftRandom;
            rightValue += rightRandom;
        }

        this.leftLabel.setText(Integer.toString(leftValue));
        this.rightLabel.setText(Integer.toString(rightValue));
    }
}

这基本上改变了基于事件源的计算方向——它不需要现在知道事件源是什么（按钮、菜单项、键绑定），它只是不在乎

您只需将适当的

actionCommand

应用于适当的

Jbutton

，即可设置此功能，例如

public class TestPane extends JPanel {

    private JLabel leftLabel;
    private JLabel rightLabel;

    private JButton upDownButton;
    private JButton downUpButton;

    public TestPane() {
        leftLabel = new JLabel("0");
        rightLabel = new JLabel("0");

        upDownButton = new JButton("Up/down");
        downUpButton = new JButton("Down/up");

        upDownButton.setActionCommand("upDown");
        downUpButton.setActionCommand("downUp");

        ActionListener actionListener = new IncrementDecrementAction(leftLabel, rightLabel);

        upDownButton.addActionListener(actionListener);
        downUpButton.addActionListener(actionListener);

        add(leftLabel);
        add(rightLabel);

        add(upDownButton);
        add(downUpButton);
    }

}

现在，在说到这一点之前，我经历了十几个想法-我的目的是尽量让它简单，而不试图引入一大堆可能不需要添加的复杂性-小心-我不知道这个练习的目的是什么，所以我可能走错了方向，而不是你的导师想让你做的