编译没有问题,但是运行出现一对异常,希望高手能帮忙看看
代码如下:
import java.awt.*;
class Test extends Frame
{
public Test()
{
super("User Login");
this.setLocation(300,240);
this.setSize(280,120);
this.setBackground(Color.lightGray);
this.add(new Label("userid"));
this.add(new TextField(20));
this.add(new Label("password"));
this.add(new TextField(20));
this.add(new Button ("OK"));
this.add(new Button("Cancel"));
this.setVisible(true);
}
}
public class TestFrame
{
public static void main(String[] args)
{
new Test();
}
}
代码如下:
import java.awt.*;
class Test extends Frame
{
public Test()
{
super("User Login");
this.setLocation(300,240);
this.setSize(280,120);
this.setBackground(Color.lightGray);
this.add(new Label("userid"));
this.add(new TextField(20));
this.add(new Label("password"));
this.add(new TextField(20));
this.add(new Button ("OK"));
this.add(new Button("Cancel"));
this.setVisible(true);
}
}
public class TestFrame
{
public static void main(String[] args)
{
new Test();
}
}
一般控件都是窗体的成员。你这样写把他们设为局部变量。执行完构造函数控件就消失了
我是这样运行的:
package Package13;import java.awt.Button;
import java.awt.Color;
import java.awt.Label;
import java.awt.TextField;import javax.swing.JFrame;public class MyTest3 extends JFrame{
public MyTest3()
{
super("User Login");
this.setLocation(300,240);
this.setSize(280,120);
this.setBackground(Color.lightGray);
this.add(new Label("userid"));
this.add(new TextField(20));
this.add(new Label("password"));
this.add(new TextField(20));
this.add(new Button ("OK"));
this.add(new Button("Cancel")); this.setVisible(true);
}
public static void main(String[] args)
{
new MyTest3();
}
}
建议你多用一下IDE的联想功能,让它联想出所需方法、字段,这样有助于提高准确率。