java - if 语句更简洁

Question

是否可以通过组合 if 来使其更加简洁带有 && 的语句或者是其他东西？我已经尝试了很多，但似乎无法使其发挥作用。如果我能得到关于一两行代码的任何示例，我将非常感激。订单必须保持原样。

public void actionPerformed(ActionEvent ae) {
    if (ae.getSource() == button[0])
        display.append("7");
    if (ae.getSource() == button[1])
        display.append("8");
    if (ae.getSource() == button[2])
        display.append("9");

    if (ae.getSource() == button[3]) {
        temporary[0] = Double.parseDouble(display.getText());
        function[0] = true;
        display.setText("");
    }
    if (ae.getSource() == button[4])
        display.append("4");
    if (ae.getSource() == button[5])
        display.append("5");
    if (ae.getSource() == button[6])
        display.append("6");
    if (ae.getSource() == button[7]) {

        temporary[0] = Double.parseDouble(display.getText());
        function[1] = true;
        display.setText("");
    }
    if (ae.getSource() == button[8])
        display.append("1");
    if (ae.getSource() == button[9])
        display.append("2");
    if (ae.getSource() == button[10])
        display.append("3");
    if (ae.getSource() == button[11]) {

        temporary[0] = Double.parseDouble(display.getText());
        function[2] = true;
        display.setText("");
    }
    if (ae.getSource() == button[12])
        display.append(".");
    if (ae.getSource() == button[13]) {

        temporary[0] = Double.parseDouble(display.getText());
        function[3] = true;
        display.setText("");
    }
    if (ae.getSource() == button[14])
        clear();
    if (ae.getSource() == button[15])
        getSqrt();
    if (ae.getSource() == button[16])
        getPosNeg();
    if (ae.getSource() == button[17])
        getResult();
    if (ae.getSource() == button[18])
        display.append("0");
}

Answer 1

在函数之外的某个地方，可能作为final成员，我会定义一个哈希表。

final Map<JButton, String> translation = new HashMap<>();
translation.put(button[0],  "7");
translation.put(button[1],  "8");
translation.put(button[2],  "9");
translation.put(button[4],  "4");
translation.put(button[5],  "5");
translation.put(button[6],  "6");
translation.put(button[8],  "1");
translation.put(button[9],  "2");
translation.put(button[10], "3");
translation.put(button[12], ".");
translation.put(button[18], "0");
final Map<JButton, Integer> functions = new HashMap<>();
functions.put(button[3],  0);
functions.put(button[7],  1);
functions.put(button[11], 2);
functions.put(button[13], 3);
final Map<JButton, Runnable> runnables = new HashMap<>();
runnables.put(button[14], () -> { clear(); });
runnables.put(button[15], () -> { getSqrt(); });
runnables.put(button[16], () -> { getPosNeg(); });
runnables.put(button[17], () -> { getResult(); });

然后我将按如下方式使用它:

public void actionPerformed(ActionEvent ae) {
    if(translation.keySet().contains(ae.getSource())
    {
        display.append(translation.get(ae.getSource());
        return;
    }

    if(functions.keySet().contains(ae.getSource())
    {
        temporary[0] = Double.parseDouble(display.getText());
        function[functions.get(ae.getSource())] = true;
        display.setText("");
        return;
    }

    if(runnables.keySet().contains(ae.getSource())
    {
        runnables.get(ae.getSource()).run();
        return;
    }
}