是关于布局null的啊
import java.awt.*;
import java.applet.*;public class ll extends Applet{
private Panel pane;
private ImageCanvas imgc;
public void init(){
imgc = new ImageCanvas();
pane = new Panel();
pane.add(imgc,BorderLayout.CENTER);//这种布局就可以看得到啊
//pane.setLayout(null);如果把pane的布局改为null
//pane.add(imgc); 则画布就看不到啊
add(pane,BorderLayout.CENTER);
}
}
class ImageCanvas extends Canvas {
public ImageCanvas(){
this.setBounds(0,0,300,300);//已经设置了啊
this.setBackground(Color.red);
}
public void paint(Graphics g)
{
g.drawRect(32,32,50,25);
g.setColor(Color.blue);
}
public Dimension getPreferredSize()
{
return new Dimension(100,100);
}
}
import java.awt.*;
import java.applet.*;public class ll extends Applet{
private Panel pane;
private ImageCanvas imgc;
public void init(){
imgc = new ImageCanvas();
pane = new Panel();
pane.add(imgc,BorderLayout.CENTER);//这种布局就可以看得到啊
//pane.setLayout(null);如果把pane的布局改为null
//pane.add(imgc); 则画布就看不到啊
add(pane,BorderLayout.CENTER);
}
}
class ImageCanvas extends Canvas {
public ImageCanvas(){
this.setBounds(0,0,300,300);//已经设置了啊
this.setBackground(Color.red);
}
public void paint(Graphics g)
{
g.drawRect(32,32,50,25);
g.setColor(Color.blue);
}
public Dimension getPreferredSize()
{
return new Dimension(100,100);
}
}
解决方案 »
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