testabs.java

还不错的java基本实例

/*
 * 创建日期 2006-1-25
 *
 * TODO 要更改此生成的文件的模板，请转至
 * 窗口 － 首选项 － Java － 代码样式 － 代码模板
 */
package ch4;

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Testabs extends JFrame{
    private JTextField text1;
    private JButton btnOk;
    private String str="";

    public Testabs() {
        createComponents();
        registerEventHandlers();
        layoutComponents();
         setTitle("求一个数的绝对值");
         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         pack();
    }

     private void createComponents() {
               text1 = new JTextField(10);
               btnOk = new JButton("计算");
     }

     private void registerEventHandlers() {
          btnOkActionEventHander hander1=new btnOkActionEventHander();
          btnOk.addActionListener(hander1);
     }

     private void layoutComponents() {
        Container c=this.getContentPane();
        c.setLayout(new GridLayout(2, 1));

        JPanel pane1 = new JPanel();
        pane1.add( btnOk);

        JPanel pane2 = new JPanel();
        pane2.add(text1);

        c.add(pane2);
        c.add( pane1);
    }

      private class btnOkActionEventHander implements ActionListener{
        public void actionPerformed(ActionEvent e) {
           /* double y;
			double x=Double.parseDouble(text1.getText());
			if(x>=0)
			if (x>0) 
			y=x;
			else
			y=0;
			else
			y=-x;
			str+="x="+x+"    y="+y+"\n";
			JOptionPane.showMessageDialog( null,str);
			text1.setText(""); */
            double x=Double.parseDouble(text1.getText());
            double y=0;
			if(x>=0)
				if (x>0) 
					y=x;
			else
					y=-x;
			str+="x="+x+"    y="+y+"\n";
			JOptionPane.showMessageDialog( null,str);
			text1.setText("");

        }
    }

    public static void main(String[] args) {
        JFrame.setDefaultLookAndFeelDecorated(true);
        Testabs frame=new Testabs();
        frame.setVisible(true);
       }
}