Jbutton无法解析

Question

所以基本上我已经声明了所有内容，但不知何故它们仍然无法作为一种类型进行解析。有任何想法吗？ JAVA screenshot

JRadioButton englishRadio = new JRadioButton("English");
    englishRadio.addActionListener(new ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            if(englishRadio.isSelected())
            {
                mathRadio.setSelected(false);
                historyRadio.setSelected(false);

            }
        }
    });
    englishRadio.setBounds(6, 17, 70, 23);
    PreferredSubjects.add(englishRadio);

    JRadioButton mathRadio = new JRadioButton("Math");
    mathRadio.setBounds(6, 43, 70, 23);
    PreferredSubjects.add(mathRadio);

    JRadioButton historyRadio = new JRadioButton("History");
    historyRadio.setBounds(6, 67, 70, 23);
    PreferredSubjects.add(historyRadio);

Answer 1

在声明对象之前，您不能引用对象，除非它是一个字段。尝试将您的声明 移动到 上方您的动作侦听器：

    // Declare mathRadio before you create englishRadio's actionListener.
    JRadioButton mathRadio = new JRadioButton("Math");
    mathRadio.setBounds(6, 43, 70, 23);
    PreferredSubjects.add(mathRadio);

    // Declare historyRadio before you create englishRadio's actionListener.
    JRadioButton historyRadio = new JRadioButton("History");
    historyRadio.setBounds(6, 67, 70, 23);
    PreferredSubjects.add(historyRadio);

    // Declare englishRadio before you assign it an actionListener.
    JRadioButton englishRadio = new JRadioButton("English");
    // Create the actionListener after declaring your three radios.
    englishRadio.addActionListener(new ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            if(englishRadio.isSelected())
            {
                mathRadio.setSelected(false);
                historyRadio.setSelected(false);

            }
        }
    });
    englishRadio.setBounds(6, 17, 70, 23);
    PreferredSubjects.add(englishRadio);

您可能还想查看针对 Creating Objects 的 Oracle 教程和 Using Objects. If you are unfamiliar with how fields work, there is another tutorial you will find quite handy: Declaring Member Variables

Jbutton无法解析

Jbutton cannot be resolved

java

jbutton