import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class Frame extends JFrame implements ActionListener
{Frame()
{JButton button1=new JButton("yellow");
JButton button2=new JButton("red");
JButton button3=new JButton("blue");
setLayout(new FlowLayout());
add(button1);
add(button2);
add(button3);
button1.addActionListener(this);
button2.addActionListener(this);
button3.addActionListener(this);
setBounds(100,100,300,300);
}
public void actionPerformed(ActionEvent e)
{if(e.getSource()==button1)
{button1.setBackground(Color.YELLOW);
}
if(e.getSource()==button2)
{button2.setBackground(Color.RED);
}
if(e.getSource()==button3)
{button3.setBackground(Color.BLUE);
}
}
JButton button1,button2,button3;}
public class Eva
{public static void main(String args[])
{Frame frame=new Frame();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
我想让按钮改变颜色,为什么变不了呢。
import javax.swing.*;
import java.awt.event.*;
class Frame extends JFrame implements ActionListener
{Frame()
{JButton button1=new JButton("yellow");
JButton button2=new JButton("red");
JButton button3=new JButton("blue");
setLayout(new FlowLayout());
add(button1);
add(button2);
add(button3);
button1.addActionListener(this);
button2.addActionListener(this);
button3.addActionListener(this);
setBounds(100,100,300,300);
}
public void actionPerformed(ActionEvent e)
{if(e.getSource()==button1)
{button1.setBackground(Color.YELLOW);
}
if(e.getSource()==button2)
{button2.setBackground(Color.RED);
}
if(e.getSource()==button3)
{button3.setBackground(Color.BLUE);
}
}
JButton button1,button2,button3;}
public class Eva
{public static void main(String args[])
{Frame frame=new Frame();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
我想让按钮改变颜色,为什么变不了呢。
import javax.swing.*;
import java.awt.event.*;
class Frame extends JFrame implements ActionListener
{
JButton button1=new JButton("yellow");
JButton button2=new JButton("red");
JButton button3=new JButton("blue");
Frame()
{
setLayout(new FlowLayout());
add(button1);
add(button2);
add(button3);
button1.addActionListener(this);
button2.addActionListener(this);
button3.addActionListener(this);
setBounds(100,100,300,300);
}
public void actionPerformed(ActionEvent e)
{if(e.getSource()==button1)
{button1.setBackground(Color.YELLOW);
}
if(e.getSource()==button2)
{button2.setBackground(Color.RED);
}
if(e.getSource()==button3)
{button3.setBackground(Color.BLUE);
}
}}
public class Eva
{public static void main(String args[])
{Frame frame=new Frame();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Frame()
{JButton button1=new JButton("yellow"); //这里的button1,2,3是局部变量,
JButton button2=new JButton("red"); //把前面的JButton都去掉
JButton button3=new JButton("blue");