简易计算器小程序代码：

package jisuanqi;

//声明须要插入的包

import java.awt.*;

import java.lang.Object;

import java.lang.String;

import javax.swing.*;

import java.awt.event.*;

import java.awt.TextComponent;

//声明一个主类jisuanqi。继续窗体类Frame

public class jisuanqi extends Frame{

	//声明16个Button

	Button anjian1, anjian2, anjian3, anjian4, anjian5, anjian6, anjian7, anjian8, anjian9, anjian10, anjian11, anjian12, anjian13, anjian14,anjian15,anjian16;

	//声明文本框。用于接收数字和计算

	TextField numText;

	//声明面板容器，用于存放各种button

	Panel anjianPanel;

	//构造方法初始化button

	jisuanqi(String title){

		super(title);

		anjian1=new Button("0");

		anjian2=new Button("1");

		anjian3=new Button("2");

		anjian4=new Button("3");

		anjian5=new Button("4");

		anjian6=new Button("5");

		anjian7=new Button("6");

		anjian8=new Button("7");

		anjian9=new Button("8");

		anjian10=new Button("9");

		anjian11=new Button("+");

		anjian12=new Button("-");

		anjian13=new Button("*");

		anjian14=new Button("/");

		anjian15=new Button("=");

		anjian16=new Button("清空");

		//初始化文本框。将文本的值设置为“0”

		numText=new TextField("0");

		//实例化面板;

		anjianPanel=new Panel();

		//设置button

		anjianPanel.setLayout(new FlowLayout());

		//实例化button

		anjian1.addActionListener(new anjianAction());

		anjian2.addActionListener(new anjianAction());

		anjian3.addActionListener(new anjianAction());

		anjian4.addActionListener(new anjianAction());

		anjian5.addActionListener(new anjianAction());

		anjian6.addActionListener(new anjianAction());

		anjian7.addActionListener(new anjianAction());

		anjian8.addActionListener(new anjianAction());

		anjian9.addActionListener(new anjianAction());

		anjian10.addActionListener(new anjianAction());

		anjian11.addActionListener(new anjianAction());

		anjian12.addActionListener(new anjianAction());

		anjian13.addActionListener(new anjianAction());

		anjian14.addActionListener(new anjianAction());

		anjian15.addActionListener(new anjianAction());

		anjian16.addActionListener(new anjianAction());

		//将各个button加入到面板容器中

		anjianPanel.add(anjian1);

		anjianPanel.add(anjian2);

		anjianPanel.add(anjian3);

		anjianPanel.add(anjian4);

		anjianPanel.add(anjian5);

		anjianPanel.add(anjian6);

		anjianPanel.add(anjian7);

		anjianPanel.add(anjian8);

		anjianPanel.add(anjian9);

		anjianPanel.add(anjian10);

		anjianPanel.add(anjian11);

		anjianPanel.add(anjian12);

		anjianPanel.add(anjian13);

		anjianPanel.add(anjian14);

		anjianPanel.add(anjian15);

		anjianPanel.add(anjian16);

		//为文本框加入事件

		numText.addTextListener(new TextListener() {

			public void textValueChanged(TextEvent e) {

				if(numText.getText().indexOf("0",0)!=-1){

					numText.getText().replace("0","");

				}

			}

		});

		addWindowListener(new WindowAdapter() {

			public void windowClosing(WindowEvent e) {

				System.exit(0);

			}

		});

		//将文本框放置在顶部

		add(numText,BorderLayout.NORTH);

		//加入button

		add(anjianPanel,BorderLayout.CENTER);

		//设置文本框属性

		numText.setEditable(false);

	}

	//没有不论什么操作的值

	int num=0;

	//numStr是文本框的值

	String numStr=null;

	Boolean chinage=false;

	//设置button

	public int check(){

	numStr = numText.getText();

	if (numStr.indexOf("+") == 0) {

		numStr = numStr.replace('+', '0');

		num = num + Integer.parseInt(numStr);

		return num;

	}

	else if (numStr.indexOf("-") != -1) {

		numStr = numStr.replace("-", "0");

		num = num - Integer.parseInt(numStr);

		return num;

	}

	else if(numStr.indexOf("*")!=-1){

		numStr=numStr.replace('*','0');

		num = num * Integer.parseInt(numStr);

		return num;

	}

	else if(numStr.indexOf("/")!=-1){

		numStr=numStr.replace('/','0');

		try{

			num = num / Integer.parseInt(numStr);

			return num;

		}

		catch(ArithmeticException e){

			JOptionPane.showMessageDialog(null,"除数不能为空!","消息!",1);

			return num;

		}

	}

	else return num=Integer.parseInt(numStr);

	}

	//创建事件

	private class anjianAction implements ActionListener{

		public void actionPerformed(ActionEvent event){

			if(event.getActionCommand()=="0"){

				if(!numText.getText().equals("0"))

					numText.setText(numText.getText()+0);

			}

			if(event.getActionCommand()=="1")

				numText.setText(numText.getText()+1);

			if(event.getActionCommand()=="2")

				numText.setText(numText.getText()+2);

			if(event.getActionCommand()=="3")

				numText.setText(numText.getText()+3);

			if(event.getActionCommand()=="4")

				numText.setText(numText.getText()+4);

			if(event.getActionCommand()=="5")

				numText.setText(numText.getText()+5);

			if(event.getActionCommand()=="6")

				numText.setText(numText.getText()+6);

			if(event.getActionCommand()=="7")

				numText.setText(numText.getText()+7);

			if(event.getActionCommand()=="8")

				numText.setText(numText.getText()+8);

			if(event.getActionCommand()=="9")

				numText.setText(numText.getText()+9);

			if(event.getActionCommand()=="清空"){

				numText.setText("0");

				num=0;

			}

			if(event.getActionCommand()=="+"){

				//调用check();方法

				check();

				numText.setText("+");

			}

			if(event.getActionCommand()=="-"){

				check();

				numText.setText("-");

			}

			if(event.getActionCommand()=="*"){

				check();

				numText.setText("*");

			}

			if(event.getActionCommand()=="/"){

				if(numStr=="/0"){

					JOptionPane.showMessageDialog(null,"除数不能为空!","消息!",1);

				}

				check();

				numText.setText("/");

			}

			if(event.getActionCommand()=="="){

				check();

				numText.setText(""+num);

			}

		}

	}

	public static void main(String[] args){

		jisuanqi jisuanqi=new jisuanqi("计算器");

		jisuanqi.setBackground(Color.CYAN);

		jisuanqi.setSize(300,280);

		//设置窗体大小

		jisuanqi.setLocation(550,350);

		//设置界面属性

		jisuanqi.setVisible(true);

	}

}