calculator.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 java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Calculator extends JFrame{
 private JButton btnOk ;
 private JButton btnClear ;
 private JTextField text1;
 private JTextField text2;
 private JTextField text3;
 private JTextField text4;
 private JLabel label1;
 private JLabel label2;
 private JLabel label3;
 private JLabel label4;
 
 public Calculator(){
        createComponents();
        registerEventHandlers();
        layoutComponents();
        setTitle("简易计算器");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
  
 }
 public void createComponents(){
  
  btnOk = new JButton("计算");
  btnClear = new JButton("清除");
  text1 = new JTextField(8);
  text2 = new JTextField(8);
  text3 = new JTextField(8);
  text4 = new JTextField(8);
  label1 = new JLabel("操作数1");
  label2 = new JLabel("运算数  ");
  label3 = new JLabel("操作数2");
  label4 = new JLabel("结果     ");
 }
 
 public void layoutComponents(){
  
  Container container = this.getContentPane();
  container.setLayout(new GridLayout(5, 1));
  
  JPanel panel1 = new JPanel();
  panel1.setLayout(new FlowLayout());
  panel1.add(label1);
  panel1.add(text1);
 
  JPanel panel2 = new JPanel();
  panel2.setLayout(new FlowLayout());
  panel2.add(label2);
  panel2.add(text2);
  
  JPanel panel3 = new JPanel();
  panel3.add(label3);
  panel3.add(text3);
  
  JPanel panel4 = new JPanel();
  panel4.add(label4);
  panel4.add(text4);
  
  JPanel panel5 = new JPanel();
  panel5.add(btnOk);
  panel5.add(btnClear);
   
  container.add(panel1);
  container.add(panel2);
  container.add(panel3);
  container.add(panel4);
  container.add(panel5);
 }
 public void registerEventHandlers(){
     btnOkActionEventHander hander1 = new btnOkActionEventHander();
     btnOk.addActionListener(hander1);
     btnClearActionEventHander hander2 = new btnClearActionEventHander();
     btnClear.addActionListener(hander1);
 }
     
 public class btnOkActionEventHander implements ActionListener{
     public void actionPerformed(ActionEvent e){
             
			float op1=Float.parseFloat(text1.getText());
			float op2=Float.parseFloat(text3.getText());
			//String str=
			char operator=(text2.getText()).charAt(0);
			switch(operator)
			{
				case '+':
					op1+=op2;
					break;
				case '-':
					op1-=op2;
					break;
				case '*':
					op1*=op2;
					break;
				case '/':
					op1/=op2;
					break;
                                 case '%':
					op1%=op2;
					break;
				default:
				    JOptionPane.showMessageDialog(null,"错误!输入的不是运算符号!");
					break;
			}   
       text4.setText(String.valueOf(op1));
     }
    }
 public class btnClearActionEventHander implements ActionListener{
     public void actionPerformed(ActionEvent e){
         text1.setText("");
         text2.setText("");
         text3.setText("");
         text4.setText("");
     }
     }
 
 public static void main(String[] args){
        JFrame.setDefaultLookAndFeelDecorated(true);
        Calculator frame= new Calculator();
        frame.setVisible(true);
    }
}