各位高手们，请帮帮我，谢谢！！！！

[xueguoqing]

各位大侠们：我是个新手才学java两天，遇到一个问题想请教，有个程序编译能通过，但执行的时候提示如下：
Exception in thread "main" java.lang.IllegalArgumentException: cannot add to lay
out: unknown constraint: BorderLayout.NORTH
at java.awt.BorderLayout.addLayoutComponent(BorderLayout.java:437)
at java.awt.BorderLayout.addLayoutComponent(BorderLayout.java:399)
at java.awt.Container.addImpl(Container.java:664)
at java.awt.Container.add(Container.java:518)
at TwoListen.go(Xue.java:16)
at TwoListen.main(Xue.java:10)
Press any key to continue...
请问是什么意思，为什么会出现这种情况，是哪个地方逻辑出错了吗？
程序如下：
import java.awt.*;
import java.awt.event.*;

class TwoListen implements MouseMotionListener, MouseListener {
private Frame f;
private TextField tf;

public static void main(String args[]) {
TwoListen two = new TwoListen();
two.go();
}


public void go() {
f = new Frame("Two listeners example");
f.add (new Label ("Click and drag the mouse"), "BorderLayout.NORTH");
tf = new TextField (30);
f.add (tf, "BorderLayout.SOUTH");

f.addMouseMotionListener(this);
f.addMouseListener (this);
f.setSize(300, 200);
f.setVisible(true);
}

// These are MouseMotionListener events
public void mouseDragged (MouseEvent e) {
String s = "Mouse dragging: X = " + e.getX() + " Y = " + e.getY();
tf.setText (s);
}

public void mouseMoved (MouseEvent e) {
}

// These are MouseListener events
public void mouseClicked (MouseEvent e) {
}

public void mouseEntered (MouseEvent e) {
String s = "The mouse entered";
tf.setText (s);
}

public void mouseExited (MouseEvent e) {
String s = "The mouse has left the building";
tf.setText (s);
}

public void mousePressed (MouseEvent e) {
}

public void mouseReleased (MouseEvent e) {
}
}
注：我的程序是在jcreator中运行并编译的java环境是sdk1.4.1

[liuchuan]

好象是这里了，提示是参数错误。

f.add (tf, "BorderLayout.SOUTH");

BorderLayout.SOUTH是个静态变量，去掉双引号再试试。

[xueguoqing]

还是不行

[kinzey34]

是多了双引号的原因，去掉后可以运行：

import java.awt.*;
import java.awt.event.*;

class TwoListen implements MouseMotionListener, MouseListener {
private Frame f;
private TextField tf;

public static void main(String args[]) {
TwoListen two = new TwoListen();
two.go();
}

public void go() {
f = new Frame("Two listeners example");
//去掉引号后
f.add (new Label("Click and drag the mouse"),BorderLayout.NORTH);
tf = new TextField (30);
//去掉引号后
f.add (tf,BorderLayout.SOUTH);

f.addMouseMotionListener(this);
f.addMouseListener (this);
f.setSize(300, 200);
f.setVisible(true);
}
// These are MouseMotionListener events
public void mouseDragged (MouseEvent e) {
String s = "Mouse dragging: X = " + e.getX() + " Y = " + e.getY();
tf.setText (s);
}
public void mouseMoved (MouseEvent e) {
}
// These are MouseListener events
public void mouseClicked (MouseEvent e) {
}
public void mouseEntered (MouseEvent e) {
String s = "The mouse entered";
tf.setText (s);
}

public void mouseExited (MouseEvent e) {
String s = "The mouse has left the building";
tf.setText (s);
}
public void mousePressed (MouseEvent e){}
public void mouseReleased (MouseEvent e){}
}

[xueguoqing]

去掉双引号后编译也不能通过了，他提示没有双引号的地方出错了，提示为--------------------Configuration: xue - j2sdk <Default>--------------------
d:\JCreator Pro\MyProjects\xue\Xue.java:16: illegal character: \65292
f.add (new Label ("Click and drag the mouse")， BorderLayout.NORTH);
^
1 error

Process completed.

[liuchuan]

逗号是不是输成中文模式下的了？