testgui.java

一些简单的java程序。老师很认真

package com.test;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class TestGUI extends JFrame implements ActionListener{
  JTextField op1=new JTextField();
  JComboBox opr=new JComboBox();
  JTextField op2=new JTextField();
  JLabel l1=new JLabel("=");
  JTextField result=new JTextField();
  JButton b1=new JButton("ok");
  JTextArea analysis=new JTextArea();
  TestGUI(){
	  super("test frame");
      setSize(3000,1000);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      Container content = this.getContentPane();
      content.setLayout(new GridBagLayout());
      JPanel p=new JPanel();
      this.op1.setSize(20,20);
      this.op1.setText("       ");
      this.op2.setSize(20,20);
	  this.op2.setText("       ");
	  this.opr.addItem("+");
	  this.opr.addItem("-");
	  this.opr.addItem("*");
	  this.opr.addItem("/");
	  this.opr.addActionListener(this);
	  this.opr.setSize(20,20);
	  this.result.setText("      ");
	  this.b1.addActionListener(this);
	  this.analysis.setSize(200,300);
	  this.analysis.setText("The analysis is:                ");
	  p.add(this.op1);
	  p.add(this.opr);
	  p.add(this.op2);
	  p.add(this.l1);
	  p.add(this.result);
	  p.add(this.b1);
	  p.add(this.analysis);
	  content.add(p);
	  this.pack();
	  setVisible(true);
  }
  public void actionPerformed(ActionEvent e){
	  Double r;
	  r=0.0;
	  Object o=e.getSource();
	  try{
	  if (o==this.opr)
		  System.out.println(this.opr.getSelectedItem());
	  if(o==this.b1)
		  {
		   System.out.println("the button1 is pressed");
		   if (this.opr.getSelectedItem()=="+")
			    {
		    	  r=Double.parseDouble(this.op1.getText())+Double.parseDouble(this.op2.getText());
			      this.result.setText(r.toString());
			   }
	       if (this.opr.getSelectedItem()=="-")
	           {
  	              r=Double.parseDouble(this.op1.getText())-Double.parseDouble(this.op2.getText());
	              this.result.setText(r.toString());
	            }
           if (this.opr.getSelectedItem()=="*")
                {
	              r=Double.parseDouble(this.op1.getText())*Double.parseDouble(this.op2.getText());
                  this.result.setText(r.toString());
                }
           if (this.opr.getSelectedItem()=="/")
		    {
               if ((int)Double.parseDouble(this.op2.getText())==0)
            	 System.out.println("0 can not be divided");
               else
               {
            	   r=Double.parseDouble(this.op1.getText())/Double.parseDouble(this.op2.getText());
		           this.result.setText(r.toString());
               }
		   }
		  }}catch(Exception ee){}
  }
  public static void main(String[] args){
	  TestGUI t=new TestGUI();
  } 
}