Java无法找到符号

Question

这是我的错误消息

test.java:17: cannot find symbol
symbol  : class MouseAdapter
location: class test
        private class click extends MouseAdapter
                                    ^
test.java:19: cannot find symbol
symbol  : class MouseEvent
location: class test.click
                public void mouseEntered(MouseEvent e)
                                         ^
test.java:14: cannot find symbol
symbol  : variable trayicon
location: class test
        trayicon.addMouseListener(new click());
        ^
3 errors

---

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

public class test extends JFrame
{

    private JFrame frame;

    public void init()
    {
        trayicon.addMouseListener(new click());
    }

        private class click extends MouseAdapter
        {
            public void mouseEntered(MouseEvent e)
            {
                {
                frame.setVisible(true);
            }
        }
    }
}

Answer 1

你需要：

import java.awt.event.*;

编辑：

你需要声明trayicon：

JLabel trayicon = new JLabel();

Answer 2

加入mellamokb，您使用的不被任何声明的变量托盘图标 。

所以加

import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

并声明trayicon

Answer 3

再现错误：

$cat >test.java <<. 
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;

public class test extends JFrame
{

    private JFrame frame;

    public void init()
    {
        trayicon.addMouseListener(new click());
    }

        private class click extends MouseAdapter
        {
            public void mouseEntered(MouseEvent e)
            {
                {
                frame.setVisible(true);
            }
        }
    }
}
.
$javac test.java 
test.java:15: cannot find symbol
symbol  : class MouseAdapter
location: class test
        private class click extends MouseAdapter
                                    ^
test.java:17: cannot find symbol
symbol  : class MouseEvent
location: class test.click
            public void mouseEntered(MouseEvent e)
                                     ^
test.java:12: cannot find symbol
symbol  : variable trayicon
location: class test
        trayicon.addMouseListener(new click());
        ^
3 errors

添加导入

$ed test.java 
431
1i
import java.awt.event.*;
.
wq
456
$javac test.java 
test.java:13: cannot find symbol
symbol  : variable trayicon
location: class test
        trayicon.addMouseListener(new click());
        ^
1 error

在第13行声明trayicon

$ed test.java 
456
13i
        JLabel trayicon = new JLabel();// or something that makes sense
.
wq
528
$javac test.java 
$

固定！

结果代码：

$cat test.java 
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;

public class test extends JFrame
{

    private JFrame frame;

    public void init()
    {
        JLabel trayicon = new JLabel();// or something that makes sense
        trayicon.addMouseListener(new click());
    }

        private class click extends MouseAdapter
        {
            public void mouseEntered(MouseEvent e)
            {
                {
                frame.setVisible(true);
            }
        }
    }
}

顺便说一句，你不需要第26和21行：

$ed test.java 
633
26d
21d
wq
605
$javac test.java 
$
$cat test.java 
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;

public class test extends JFrame
{

    private JFrame frame;

    public void init()
    {
        JLabel trayicon = new JLabel();// or something that makes sense
        trayicon.addMouseListener(new click());
    }

        private class click extends MouseAdapter
        {
            public void mouseEntered(MouseEvent e)
            {
                frame.setVisible(true);
            }
        }
    }