如何修复java中action listener中的错误？

JButton button = new JButton("Click me");
button.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        // 确保对象不为null
        if (someObject != null) {
            someObject.doSomething();
        } else {
            System.out.println("someObject is null");
        }
    }
});

JButton button = new JButton("Click me");
button.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        Object source = e.getSource();
        if (source instanceof JButton) {
            JButton clickedButton = (JButton) source;
            // 处理按钮点击事件
        }
    }
});

JButton button = new JButton("Click me");
button.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        int value = getValue();
        if (value > 0) {
            // 处理正值情况
        } else if (value < 0) {
            // 处理负值情况
        } else {
            // 处理零值情况
        }
    }

    private int getValue() {
        // 返回一个整数值
        return 0;
    }
});