import java.awt.*;
import javax.swing.*;
public class
import javax.swing.*;
import java.awt.*;
import javax.swing.tree.*;
import javax.swing.event.*;
/*<applet code="JT.class" width=200 height=300>
</applet>*/
public class JT extends JApplet {
JTree tree;
JTextField box;
Object nodeInfo;
String node1;
public void init() {
Container c=getContentPane();
c.setLayout(new BorderLayout());
DefaultMutableTreeNode topNode=new DefaultMutableTreeNode("qiscet");
DefaultMutableTreeNode cou=new DefaultMutableTreeNode("Courses");
DefaultMutableTreeNode mca=new DefaultMutableTreeNode("MCA");
DefaultMutableTreeNode mba=new DefaultMutableTreeNode("MBA");
DefaultMutableTreeNode tech=new DefaultMutableTreeNode("B.tech");
topNode.add(cou);
cou.add(mca);
cou.add(mba);
cou.add(tech);
DefaultMutableTreeNode manage=new DefaultMutableTreeNode("Management");
DefaultMutableTreeNode ac=new DefaultMutableTreeNode("Accounts");
DefaultMutableTreeNode sp=new DefaultMutableTreeNode("Sports");
DefaultMutableTreeNode lib=new DefaultMutableTreeNode("Library");
topNode.add(manage);
manage.add(ac);
manage.add(sp);
manage.add(lib);
tree=new JTree(topNode);
c.add(tree,BorderLayout.NORTH);
box=new JTextField("",80);
c.add(box,BorderLayout.SOUTH);
}
}
我的问题是没有使用“Container c = getContentPane();”我得到了正确的输出。怎么可能?这是什么原因?
答案 0 :(得分:14)
从Swing开始,你可以使用getContentPane()来实现add()和setLayout()之类的东西,让你意识到有不同的层。过了一段时间,我猜他们承认这是一个痛苦,所以他们在内部调用了getContentPane(),所以你不再需要了。
最后,经过七年,我们已经做到了 jFrame.add相当于 jFrame.getContentPane()。添加()
And here is a link to the rationale behind the original reason.