Question

我对Java编码相对较新，刚刚涉及GUI和用户生成事件的主题。我试图制作一个简单的基于按钮的叙述，但是这个错误会继续弹出：

线程“AWT-EventQueue-0”中的异常java.lang.Error：未解决的编译问题： careerNew无法解决变量 responseText无法解析为变量

at SalutonFrame.actionPerformed(SalutonFrame.java:56)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

这是我的源代码：

>import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

>public class SalutonFrame extends JFrame implements ActionListener {
    >public SalutonFrame() {
        super("Saluton Mondo!");
        setLookAndFeel();
        setSize(1000, 500);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        FlowLayout flow = new FlowLayout(FlowLayout.CENTER, 10, 10);
        setLayout(flow);
        >//set row 1
            >JButton careerNew = new JButton("Begin your programming career!");
            careerNew.addActionListener(this);
            JLabel responseLabel = new JLabel("YourResponse:", JLabel.RIGHT);
            JComboBox choiceResponse = new JComboBox();
            choiceResponse.addItem("Yes");
            choiceResponse.addItem("No, I'm an idiot");
            JTextField responseText = new JTextField(20);
            add(careerNew);
            add(choiceResponse);
            add(responseLabel);
            add(responseText);
        //set row 2
        JPanel badCareer = new JPanel();
            JButton startBad = new JButton("Start a life of misery");
            JLabel startBadLabel = new JLabel("Your Response, Not that it Matters though:", JLabel.RIGHT);
            JTextField startBadText = new JTextField (20);
            JComboBox startBadCombo = new JComboBox();
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("You dont have a choice");
            startBadCombo.addItem("Dafuq u still looking?");
            badCareer.add(startBad);
            badCareer.add(startBadLabel);
            badCareer.add(startBadCombo);
            badCareer.add(startBadText);
        add(badCareer);




        setVisible(true);
    }
    // sets User-generated event from button careerNew
        public void actionPerformed(ActionEvent event) {
            Object source = event.getSource();
            if (source.equals (careerNew)) {
            CareerGood career = new CareerGood();
            }
            else if (source == responseText) {
                JLabel fart = new JLabel("Idiot");

            }
        }



    private void setLookAndFeel() {
        try {
            UIManager.setLookAndFeel(
                    "com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
        }
        catch (Exception exc) {


        }
    }
        public static void main(String[] args) {
            SalutonFrame frame = new SalutonFrame();        }
    }

是的，我确实忽略了Eclipse在发生错误时向我发送的有关正在运行的消息。请帮助我，因为我只是一个初学者，并希望有一个Java编程的职业生涯。谢谢！

Answer 1

您已将careerNew声明为本地变量

JButton careerNew = new JButton("Begin your programming career!");

其范围仅限于构造函数。您不能像在actionPerformed()方法中那样在构造函数体外部引用它。你应该把它变成一个实例变量。您将能够以任何实例方法访问它。

同样适用于responseText。

Answer 2

Java变量具有范围，这意味着它们只能在它们所在的括号集中访问。现在，Java无法找到变量responseText和careerNew。要解决这个问题，只需将它们公之于众。

无法在AWT中定义变量

2 个答案: