请看以下代码:
import java.awt.*;
import java.awt.event.*;
public class ChangeColor extends Frame implements ActionListener
{
static ChangeColor cc=new ChangeColor();
static Button btn=new Button("ChangeColor");
public static void main(String args[])
{
//注册
btn.addActionListener(cc);
cc.setLayout(new FlowLayout());
cc.setTitle("Action event");
cc.setSize(200,200);
cc.add(btn);
cc.show();
}
//事件处理
public void actionPerformed(ActionEvent e)
{
cc.setBackground(Color.blue);
}
}请问:为什么在static ChangeColor cc=new ChangeColor();
和static Button btn=new Button("ChangeColor");两条语句前加上“static”???
import java.awt.*;
import java.awt.event.*;
public class ChangeColor extends Frame implements ActionListener
{
static ChangeColor cc=new ChangeColor();
static Button btn=new Button("ChangeColor");
public static void main(String args[])
{
//注册
btn.addActionListener(cc);
cc.setLayout(new FlowLayout());
cc.setTitle("Action event");
cc.setSize(200,200);
cc.add(btn);
cc.show();
}
//事件处理
public void actionPerformed(ActionEvent e)
{
cc.setBackground(Color.blue);
}
}请问:为什么在static ChangeColor cc=new ChangeColor();
和static Button btn=new Button("ChangeColor");两条语句前加上“static”???
解决方案 »
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