如何用JAVA语言编写计算器小程序？

import java.io.File;

import java.io.FilenameFilter;

import java.util.Scanner;

public class IoFilter {

private static Scanner san = new Scanner(System.in);

public static File[] doFilter(File dist, String tail) {

FilenameFilter filter = new JavaFileFilter(tail);

File[] fs = dist.listFiles(filter);

return fs;

}

public IoFilter() {

}

public static void list(File [] fs) {

if(fs == null) {

return;

}

for(File f: fs) {

System.out.println(f.getName());

}

}

public static void main(String[] args) {

String path = ".";

System.out.print("Input dist path: ");

path = san.nextLine();

File dist = new File(path);

System.out.print("filter(input dir *): ");

String input = san.nextLine();

input = input.trim();

if(!input.matches("dir.*")) {

System.err.println("Error Command!");

System.exit(-1);

return;

} else if(input.equals("dir")){

IoFilter.list(IoFilter.doFilter(dist, null));

return;

} else {

String tail = null;

tail = input.replaceFirst("dir\\s", "");

IoFilter.list(IoFilter.doFilter(dist, tail));

return;

}

}

}

class JavaFileFilter implements FilenameFilter {

private String tail = ".*";

private String filter = ".*\\.";

public JavaFileFilter(String tail) {

this.tail = tail;

}

public boolean accept(File dir, String name) {

if (this.tail == null) {

this.filter = ".*";

} else {

this.filter = ".*\\." + this.tail;

}

return name.matches(this.filter);

}

}

具体代码如下：

import javax.swing.*;

import java.awt.event.*;

import java.awt.*;

public class Calculator  extends JFrame implements ActionListener  {

private JFrame jf;

private JButton[] allButtons;

private JButton clearButton;

private JTextField jtf;

public Calculator() {

//对图形组件实例化

jf=new JFrame("任静的计算器1.0：JAVA版");

jf.addWindowListener(new WindowAdapter(){

public void windowClosing(){

System.exit(0);

}

});

allButtons=new JButton[16];

clearButton=new JButton("清除");

jtf=new JTextField(25);

jtf.setEditable(false);

String str="123+456-789*0.=/";

for(int i=0;i

allButtons[i]=new JButton(str.substring(i,i+1));

}我爱编程网

}

public void init(){

//完成布局

jf.setLayout(new BorderLayout());

JPanel northPanel=new JPanel();

JPanel centerPanel=new JPanel();

JPanel southPanel=new JPanel();

northPanel.setLayout(new FlowLayout());

centerPanel.setLayout(new GridLayout(4,4));

southPanel.setLayout(new FlowLayout());

northPanel.add(jtf);

for(int i=0;i<16;i++){

centerPanel.add(allButtons[i]);

}

southPanel.add(clearButton);

jf.add(northPanel,BorderLayout.NORTH);

jf.add(centerPanel,BorderLayout.CENTER);

jf.add(southPanel,BorderLayout.SOUTH);

addEventHandler();

}

//添加事件监听

public void addEventHandler(){

jtf.addActionListener(this);

for(int i=0;i

allButtons[i].addActionListener(this);

}

clearButton.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e) {

// TODO Auto-generated method stub

Calculator.this.jtf.setText("");

}

});

}

//事件处理

public void actionPerformed(ActionEvent e) {

//在这里完成事件处理  使计算器可以运行

String action=e.getActionCommand();

if(action=="+"||action=="-"||action=="*"||action=="/"){

}

}

public void setFontAndColor(){

Font f=new Font("宋体",Font.BOLD,24);

jtf.setFont(f);

jtf.setBackground(new Color(0x8f,0xa0,0xfb));

for(int i=0;i<16;i++){

allButtons[i].setFont(f);

allButtons[i].setForeground(Color.RED);

}

}

public void showMe(){

init();

setFontAndColor();

jf.pack();

jf.setVisible(true);

jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

public static void main(String[] args){

new Calculator().showMe();

}

}

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.IOException;

import javax.swing.JButton;

import javax.swing.JFileChooser;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JScrollPane;

import javax.swing.JTextArea;

public class Test extends JFrame implements ActionListener {

JFrame jf;

JPanel jp,jp2;

JTextArea jta;

JButton jb;

public Test(){

jf = new JFrame("查找并显示中文");

jp = new JPanel();

jp.setLayout(new GridLayout(2,1));

jf.add(jp,"Center");

jta = new JTextArea("请打开文件");

jp.add(new JScrollPane(jta));

jta.setLineWrap(true);

jp2 = new JPanel();

jp.add(jp2);

jb = new JButton("打开");

jp2.add(jb);

jb.addActionListener(this);

jf.setBounds(300, 250, 600, 300);

jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

jf.setVisible(true);

}

/**

* @param args

*/

public static void main(String[] args) {

Test test = new Test();

}

@Override

public void actionPerformed(ActionEvent e) {

if(e.getActionCommand().equals("打开")){

JFileChooser jfc = new JFileChooser("C:\\");

int returnVal = jfc.showOpenDialog(this);

if(returnVal==JFileChooser.APPROVE_OPTION){

jta.setText(null);

File file = jfc.getSelectedFile();

//添加文件操作

try {

BufferedReader br = new BufferedReader(new FileReader(file));

String line = null;

while((line=br.readLine())!=null){

char[] chars = line.toCharArray();

StringBuffer sb = new StringBuffer();

for(int i = 0;i

int num = (int)chars[i];

if(num>=19968 && num <= 171941){

sb.append(chars[i]);

}

}

if(sb.length()>0){

jta.setText(jta.getText()+sb+"\n");

}

}

} catch (FileNotFoundException e1) {

e1.printStackTrace();

} catch (IOException e2) {

e2.printStackTrace();

}

}

}

}

}

保存为Test.java编译运行即可