这个TextField的显示为什么总是不完全？

[mixianger]

程序：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TestInput extends Container
{
int x=0;
int Height=0,Width=0;

TextField textfield;
JPanel panel;
String text="";
Dimension dt;
Dimension dc;

public TestInput()
{
super();
panel=new JPanel();
textfield=new TextField(15);

textfield.setLocation(200,0);
panel.add(textfield);
this.add(panel);
}

public int getWidth()
{
return Width=301;
}

public int getHeight()
{
return Height=25;
}

}
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TestFrame extends JFrame
{
public TestFrame()
{
JFrame f=new JFrame("Test");

TestInput input=new TestInput();
input.setLocation(0,20);
System.out.println("Input's width: "+input.getWidth()+","+"Input's heitht: "+input.getHeight());

this.setLayout(new BorderLayout());
getContentPane().add("North",new Label("This is a test label!This is a test label!These are books for the students!"));
getContentPane().add("Center",input);
getContentPane().add("South",new Label("This is a test label!"));
}
public static void main(String args[])
{
TestFrame app=new TestFrame();
app.setSize(500,400);
app.setVisible(true);

app.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
}
}
显示出来以后，那个TextField总是向左偏移了一些，显示不完全。不明白为什么？
请各位大侠赐教！

[f_acme]

会不会是那个Input继承了Container的缘故？看不出来。

[mixianger]

还有别的更好的想法或解释吗？
期盼大家的帮助！
谢谢！

[f_acme]

把继承container改为继承JPanle就可以了。

[f_acme]

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

class TestInput extends JPanel {
int x = 0;

int Height = 0, Width = 0;

TextField textfield;

JPanel panel;

String text = "";

Dimension dt;

Dimension dc;

public TestInput() {
super();
panel = new JPanel();
panel.setLayout(new FlowLayout());
textfield = new TextField(15);
panel.add(textfield);
this.add(panel);
}

public int getWidth() {
return Width = 301;
}

public int getHeight() {
return Height = 25;
}
}

public class JustTest extends JFrame {

public JustTest() {
super("Test");

TestInput input = new TestInput();
System.out.println("Input's width: " + input.getWidth() + ","
+ "Input's heitht: " + input.getHeight());

this.setLayout(new BorderLayout());
add("North",new Label("This is a test label!"));
add("Center", input);
add("South", new Label("This is a test label too!"));

setSize(500, 400);
setVisible(true);
}

public static void main(String args[]) {
new JustTest();
}
}

[mixianger]

谢谢楼上的！

[mixianger]

虽然现在这样是好用的，但是我把那个TestInput加入到Frame中去的时候是先加到一个Container中（这个Container没有用布局管理器，所以我才返回TestInput的Width和Height，用来计算坐标的。），再加入到Frame中，就算改为继承JPanel结果还是一样