Question

这是列表组件的侦听器。我从人们选择它时得到一个空指针错误，但我仍然能够从数组中获取所需的信息。问题是每次单击列表项时编译器仍会抛出空指针事件。我怎么能正确访问该数组，但它仍然会抛出此错误？ class facebookListListener实现ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            moodSetter.setEnabled(true);
            String name = thePeople[facebookList.getSelectedIndex()].getName();
            String mood = thePeople[facebookList.getSelectedIndex()].getMood();
            Color lightGrey = new Color(160,160,160);
            if(mood == null){
                thePersonsMood.setText("default_mood");
                thePersonsMood.setBackground(lightGrey);

            }
            if(mood.equalsIgnoreCase("happy")){
                thePersonsMood.setText(name+"'s mood is " + mood);
                thePersonsMood.setBackground(Color.RED);
            }else{
                thePersonsMood.setText(name+"'s mood is " + mood);
                thePersonsMood.setBackground(lightGrey);
            }
            }
        }

Answer 1

啊，改变一下：

}
if(mood.equalsIgnoreCase("happy")){

到此：

} else // **** note the else!!!
if(mood.equalsIgnoreCase("happy")){

否则，即使if (mood == null)测试为真，您也会进入if块。

尽管能够访问数组，Java List Listener仍会抛出Null指针错误

1 个答案: