java - awt eventqueue 0 空指针异常错误

Question

好的，我收到此错误 awt eventqueue 0 nullpointerexception 错误。当我尝试删除 JPanel 时。

令我困惑的是，当我删除另一个 JPanel 时，它工作得很好，但这个却不行。下面的第一个代码显示了 JPanel，当我单击 JButton 时，它不会删除 JPanel。

public class buttontime implements ActionListener { //creating actionlistener for clicking on timebutton to bring up a combobox

    public void actionPerformed(ActionEvent clickTime) {
        Price priceObject = new Price();
        priceObject.getPricepanel();
        remove(priceObject.getPricepanel());
        priceObject.getPricepanel().revalidate();

        add(timeObject.getTimePanel(), BorderLayout.EAST);
        timeObject.getTimePanel().revalidate();


    }
}

//This one gives me 0 errors.
public class buttonprice implements ActionListener { //creating actionlistener for clicking on timebutton to bring up a combobox

    public void actionPerformed(ActionEvent ClickPrice) {


        Price priceObject = new Price();
        priceObject.SelectPrice();
        remove(timeObject.getTimePanel());
        timeObject.getTimePanel().revalidate();

        add(priceObject.getPricepanel(), BorderLayout.EAST);
        priceObject.getPricepanel().revalidate();


    }
}

Answer 1

remove(priceObject.getPricepanel());

如果仅在删除此面板时出现 NullPointerException，则 priceObject.getPricepanel() 必须返回 null。