Question

我已编写此代码，但出于某种原因，代码无法正常工作。它似乎应该工作，但它有点让我认为“isBasic”布尔值的值并没有真正改变，总是导致错误。谁能告诉我什么错了？

    @Override
    public void actionPerformed(ActionEvent e) {
    if (e.getActionCommand().equals("basic")){
        isBasic = true;
    }

    if (isBasic && e.getActionCommand().equals("basic")){
        isBasic = false;
    }

    if (isBasic){
        System.out.println("It works!!");
    }
}

这是JButton的代码：

    JButton basicTower = new JButton("Basic Tower");
    JButton test = new JButton("Test");
    public boolean isBasic = false;

    public TurretPanel(JPanel panel,BorderLayout layout){

    setLayout(layout);
    panel.add(basicTower,BorderLayout.WEST);
    add(panel);


    basicTower.setActionCommand("basic");
    basicTower.addActionListener(this);
}

Answer 1

你需要使用else，而不仅仅是。试试这个：

@Override
public void actionPerformed(ActionEvent e) {
    if (e.getActionCommand().equals("basic")){
        isBasic = true;
    }

    else if (isBasic && e.getActionCommand().equals("basic")){
        isBasic = false;
    }

    if (isBasic){
        System.out.println("It works!!");
    }
}

而不是

@Override
public void actionPerformed(ActionEvent e) {
    if (e.getActionCommand().equals("basic")){
        isBasic = true;
    }

    if (isBasic && e.getActionCommand().equals("basic")){
        isBasic = false;
    }

    if (isBasic){
        System.out.println("It works!!");
    }
}

编写方法的更好方法是：

@Override
public void actionPerformed(ActionEvent e) {
    if (e.getActionCommand().equals("basic")){
        isBasic = !isBasic;
    }

    if (isBasic){
        System.out.println("It works!!");
    }
}

Answer 2

这两个if语句相互否定：

if (e.getActionCommand().equals("basic")){
    isBasic = true;
}

if (isBasic && e.getActionCommand().equals("basic")){
    isBasic = false;
}

当命令等于“basic”时，两者都执行，第一个将其设置为true，第二个将其恢复为false。使用if / else：

if (e.getActionCommand().equals("basic"))
{
    isBasic = !isBasic;
}

Answer 3

我认为您遇到问题是因为您应该使用if-else语句......

想一想......我们假设e.getActionCommand()设置为"basic"

if (e.getActionCommand().equals("basic")){
    isBasic = true;
}

// isBasic is not true...

// This will now equate to true as well...
if (isBasic && e.getActionCommand().equals("basic")){
    isBasic = false;
}

// Meaning isBasic will ALWAYS be false (so long as e.getActionCommand()
// is "basic"
if (isBasic){
    System.out.println("It works!!");
}

尝试使用更像......

的内容

if (isBasic && e.getActionCommand().equals("basic")){
    isBasic = false;
} else if (e.getActionCommand().equals("basic")){
    isBasic = true;
}

相反。

您可能需要更改订单以满足您的要求，但对我来说，这更有意义......

使用JToggleButton

可能更容易

<强>更新

实际上可能更简单......

if (isBasic && e.getActionCommand().equals("basic")){
    isBasic = !isBasic;
}

Java布尔和JButtons

3 个答案: