Question

java中JFrame没有设置BorderLayout为什么还可以用

package Chapter12;
import java.awt.*;
import javax.swing.*;

public class ShowPanel extends JFrame{

/**
* @param args
*/
public ShowPanel(){
JPanel p1 = new JPanel();
p1.setLayout(new GridLayout(4,3));

for(int i=1;i<=9;i++)
p1.add(new JButton(""+i));

p1.add(new JButton(""+0));
p1.add(new JButton("Start"));
p1.add(new JButton("Stop"));

JPanel p2 = new JPanel();
p2.setLayout(new BorderLayout());

p2.add(new JTextField("Time to be displayed here"),BorderLayout.NORTH);
p2.add(p1,BorderLayout.CENTER);

add(p2,BorderLayout.EAST); // 问题在这
add(new JButton("Food to be placed here"),BorderLayout.CENTER);

}

public static void main(String[] args) {
// TODO 自动生成的方法存根
ShowPanel frame = new ShowPanel();
frame.setTitle("The Front View of a Microwave Oven");
frame.setSize(400,250);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

Answer 1

add(p2,BorderLayout.EAST);
add(new JButton("Food to be placed here"),BorderLayout.CENTER);
以上两句话已经设置了布局方式了。