常见的java项目代码,常见的java项目代码包括

求JAVA小项目的完整代码

给你个做好了的Java的源程序的记事本，自己看看就行了的，不怎么难的···

import java.awt.*;

import java.awt.event.*;

import java.io.*;

import javax.swing.*;

public class MyNotepad implements ActionListener{

private JFrame frame=new JFrame("新记事本");

private JTextArea jta=new JTextArea();

private String result="";

private boolean flag=true;

private File f;

private JButton jb=new JButton("开始");

private JTextField jtf=new JTextField(15);

private JTextField jt=new JTextField(15);

private JButton jbt=new JButton("替换为");

private JButton jba=new JButton("全部替换");

private Icon ic=new ImageIcon("D:\\java课堂笔记\\GUI\\11.gif");

private String value;

private int start=0;

private JFrame jf=new JFrame("查找");

private JFrame jfc=new JFrame("替换");

@Override

public void actionPerformed(ActionEvent e) {

String comm=e.getActionCommand();

if("新建".equals(comm)){

if(!(frame.getTitle().equals("新记事本"))){

if(!flag){

write();

newNew();

}else{

JFileChooser jfc=new JFileChooser("D:\\java课堂笔记");

int returnVal = jfc.showDialog(null,"保存为");

if(returnVal == JFileChooser.APPROVE_OPTION) {//选择文件后再执行下面的语句，保证了程序的健壮性

f=jfc.getSelectedFile();

flag=false;

write();

}

}

}else if(!(jta.getText().isEmpty())){

JFileChooser jfc=new JFileChooser("D:\\java课堂笔记");

int returnVal = jfc.showDialog(null,"保存为");

if(returnVal == JFileChooser.APPROVE_OPTION) {//选择文件后再执行下面的语句，保证了程序的健壮性

f=jfc.getSelectedFile();

flag=false;

write();

newNew();

}

}else{

newNew();

}

}else if("打开".equals(comm)){

JFileChooser jfc=new JFileChooser("D:\\java课堂笔记");

jfc.setDialogType(JFileChooser.OPEN_DIALOG);

int returnVal = jfc.showOpenDialog(null);

if(returnVal == JFileChooser.APPROVE_OPTION) {//选择文件后再执行下面的语句，保证了程序的健壮性

f=jfc.getSelectedFile();

frame.setTitle(f.getName());

result=read();

flag=false;

value=result;

jta.setText(result);

}

}else if("保存".equals(comm)){

JFileChooser jfc=new JFileChooser("D:\\java课堂笔记");

if(flag){

int returnVal = jfc.showDialog(null,"保存为");

if(returnVal == JFileChooser.APPROVE_OPTION) {//选择文件后再执行下面的语句，保证了程序的健壮性

f=jfc.getSelectedFile();

flag=false;

write();

}

}else{

write();

}

}else if("另存".equals(comm)){

JFileChooser jfc=new JFileChooser("D:\\java课堂笔记");

int returnVal = jfc.showDialog(null,"另存");

if(returnVal == JFileChooser.APPROVE_OPTION) {//选择文件后再执行下面的语句，保证了程序的健壮性

f=jfc.getSelectedFile();

write();

}

}else if("退出".equals(comm)){

System.exit(0);

}else if("撤销".equals(comm)){

jta.setText(value);

}else if("剪切".equals(comm)){

value=jta.getText();

jta.cut();

}else if("复制".equals(comm)){

jta.copy();

}else if("粘贴".equals(comm)){

value=jta.getText();

jta.paste();

}else if("删除".equals(comm)){

value=jta.getText();

jta.replaceSelection(null);

}else if("全选".equals(comm)){

jta.selectAll();

}else if("查找".equals(comm)){

value=jta.getText();

jf.add(jtf,BorderLayout.CENTER);

jf.add(jb,BorderLayout.SOUTH);

jf.setLocation(300,300);

jf.pack();

jf.setVisible(true);

jf.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

}else if("替换".equals(comm)){

value=jta.getText();

GridLayout gl=new GridLayout(3,3);

JLabel jl1=new JLabel("查找内容:");

JLabel jl2=new JLabel("替换为:");

jfc.setLayout(gl);

jfc.add(jl1);

jfc.add(jtf);

jfc.add(jb);

jfc.add(jl2);

jfc.add(jt);

jfc.add(jbt);

JLabel jl3=new JLabel();

JLabel jl4=new JLabel();

jfc.add(jl3);

jfc.add(jl4);

jfc.add(jba);

jfc.setLocation(300,300);

jfc.pack();

jfc.setVisible(true);

jfc.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

}else if("版本".equals(comm)){

JDialog jd=new JDialog(frame,"关于对话框");

jd.setSize(200,200);

JLabel l=new JLabel("哈哈哈哈哈哈哈哈哈哈呵呵呵呵呵呵呵呵呵呵呵呵呵");

jd.add(l,BorderLayout.CENTER);

jd.setLocation(100,200);

jd.setSize(300,300);

jd.setVisible(true);

// jd.pack();

jd.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);

}else if("开始".equals(comm)||"下一个".equals(comm)){

String temp=jtf.getText();

int s=value.indexOf(temp,start);

if(value.indexOf(temp,start)!=-1){

jta.setSelectionStart(s);

jta.setSelectionEnd(s+temp.length());

jta.setSelectedTextColor(Color.GREEN);

start=s+1;

jb.setText("下一个");

// value=value.substring(s+temp.length());//不能截取字串

}else {

JOptionPane.showMessageDialog(jf, "查找完毕!", "提示", 0, ic);

jf.dispose();

}

}else if("替换为".equals(comm)){

String temp=jtf.getText();

int s=value.indexOf(temp,start);

if(value.indexOf(temp,start)!=-1){

jta.setSelectionStart(s);

jta.setSelectionEnd(s+temp.length());

jta.setSelectedTextColor(Color.GREEN);

start=s+1;

jta.replaceSelection(jt.getText());

}else {

JOptionPane.showMessageDialog(jf, "查找完毕!", "提示", 0, ic);

jf.dispose();

}

}else if("全部替换".equals(comm)){

String temp=jta.getText();

temp=temp.replaceAll(jtf.getText(), jt.getText());

jta.setText(temp);

}

}

public String read(){

String temp="";

try {

FileInputStream fis = new FileInputStream(f.getAbsolutePath());

byte[] b=new byte[1024];

while(true){

int num=fis.read(b);

if(num==-1)break;

temp=temp+new String(b,0,num);

}

fis.close();

} catch (Exception e1) {

e1.printStackTrace();

}

return temp;

}

public void write(){

try {

FileOutputStream fos=new FileOutputStream(f);

fos.write(jta.getText().getBytes());

fos.close();

} catch (Exception e) {

e.printStackTrace();

}

}

public void newNew(){

frame.dispose();

new MyNotepad();

flag=true;

}

public MyNotepad(){

JMenuBar jmb=new JMenuBar();

String[] menuLab={"文件","编辑","帮助"};

String[][] menuItemLab={{"新建","打开","保存","另存","退出"},

{"撤销","剪切","复制","粘贴","删除","全选","查找","替换"},

{"版本"}};

for(int i=0;imenuLab.length;i++){

JMenu menu=new JMenu(menuLab[i]);

jmb.add(menu);

for(int j=0;jmenuItemLab[i].length;j++){

JMenuItem jmi=new JMenuItem(menuItemLab[i][j]);

menu.add(jmi);

jmi.addActionListener(this);

}

}

frame.setJMenuBar(jmb);

jta.setLineWrap(true);//自动换行

JScrollPane jsp=new JScrollPane(jta);//滚动窗口面板

frame.add(jsp);

jb.addActionListener(this);

jbt.addActionListener(this);

jba.addActionListener(this);

frame.setLocation(200,50);

frame.setSize(620,660);

frame.setVisible(true);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

public static void main(String[] args) {

new MyNotepad();

}

}

求一个50行左右的JAVA代码，最好每行带注释，谢谢啦

/*这个相当详细了.

程序也不算太难.而且给老师看的时候效果比较好.因为有图形化界面,又实现一个比较实用的功能.老师会比较高兴的.

建立一个文件名为Change.java就可以编译了*/

/*

* 这个程序实现输入身高算出标准体重,输入体重,算出身高的功能

*/

import java.awt.*; //导入相关类包,这才样使用相应awt图形界面的类

import java.awt.event.*;//同上

public class Change extends Frame { //定义一个类Change, 父类是Frame(图形界面的)

Button b = new Button("互查"); //创建一个按钮的对象b,显示为"互查"

Label l1 = new Label("身高(cm)");//创建一个lable.显示身高

Label l2 = new Label("体重(kg)");//创建一个lable 显示体重

double heigth, weigth; //定义变量

double x, y; //定义变量

TextField tf1 = new TextField(null, 10);//添加Text框

TextField tf2 = new TextField(null, 10);//添加Text框

public Change() {//类的构造函数,完成初始化

super("互查表");//创建窗口,标题为互查表

setLayout(new FlowLayout(FlowLayout.LEFT));//设置布局

add(l1);//把lable 身高放到window里

add(tf1);//把Text 框 放到窗口上

add(l2); //把lable 体重放到window里

add(tf2);//Test放到窗口里

add(b);//把button放到窗口上

pack();//自动放到窗口里排列上边的组件

setVisible(true);//可以让用户看到窗口

addWindowListener(new WindowAdapter() {//如果按 X, 关闭窗口

public void windowClosing(WindowEvent e) {

System.exit(0);

}

});

b.addActionListener(new ButtonListener());//添加button监听函数

}

class ButtonListener implements ActionListener {//实现click button时功能操作

public void actionPerformed(ActionEvent e) {//当click调用

if (tf1.getText()!=null) {//检查tf1 test 是否为空

try {//取异常

x = Double.parseDouble(tf1.getText());//字符转为double型

weigth = (x - 100) * 0.9;//算重量

tf2.setText("" + weigth);//显示重量

} catch (NumberFormatException ex) {

tf1.setText("");//如果输入不是数字,设为空

}

}

if (tf1.getText().equals("")==true){//tf1是否为空

y = Double.parseDouble(tf2.getText());//把tf2里的文本转为double 型 的

heigth = y / 0.9 + 100; //算身高根据重量

tf1.setText("" + heigth);}//显示身高

}

}

public static void main(String[] args) {//主函数,程序入口

new Change(); //建立类Change的对象,并调用他的构造函数Change().显示窗口

}

}

需求50句以上的JAVA代码，并带注解

Java文件操作大全

1.创建文件夹

//import java.io.*;

File myFolderPath = new File(%%1);

try {

if (!myFolderPath.exists()) {

myFolderPath.mkdir();

}

}

catch (Exception e) {

System.out.println("新建目录操作出错");

e.printStackTrace();

}

2.创建文件

//import java.io.*;

File myFilePath = new File(%%1);

try {

if (!myFilePath.exists()) {

myFilePath.createNewFile();

}

FileWriter resultFile = new FileWriter(myFilePath);

PrintWriter myFile = new PrintWriter(resultFile);

myFile.println(%%2);

resultFile.close();

}

catch (Exception e) {

System.out.println("新建文件操作出错");

e.printStackTrace();

}

3.删除文件

//import java.io.*;

File myDelFile = new File(%%1);

try {

myDelFile.delete();

}

catch (Exception e) {

System.out.println("删除文件操作出错");

e.printStackTrace();

}

4.删除文件夹

//import java.io.*;

File delFolderPath = new File(%%1);

try {

delFolderPath.delete(); //删除空文件夹

}

catch (Exception e) {

System.out.println("删除文件夹操作出错");

e.printStackTrace();

}

5.删除一个文件下夹所有的文件夹

//import java.io.*;

File delfile=new File(%%1);

File[] files=delfile.listFiles();

for(int i=0;ifiles.length;i++){

if(files[i].isDirectory()){

files[i].delete();

}

}

6.清空文件夹

//import java.io.*;

File delfilefolder=new File(%%1);

try {

if (!delfilefolder.exists()) {

delfilefolder.delete();

}

delfilefolder.mkdir();

}

catch (Exception e) {

System.out.println("清空目录操作出错");

e.printStackTrace();

}

7.读取文件

//import java.io.*;

// 逐行读取数据

FileReader fr = new FileReader(%%1);

BufferedReader br = new BufferedReader(fr);

String %%2 = br.readLine();

while (%%2 != null) {

%%3

%%2 = br.readLine();

}

br.close();

fr.close();

8.写入文件

//import java.io.*;

// 将数据写入文件

try {

FileWriter fw = new FileWriter(%%1);

fw.write(%%2);

fw.flush();

fw.close();

} catch (IOException e) {

e.printStackTrace();

}

9.写入随机文件

//import java.io.*;

try {

RandomAcessFile logFile=new RandomAcessFile(%%1,"rw");

long lg=logFile.length();

logFile.seek(%%2);

logFile.writeByte(%%3);

}catch(IOException ioe){

System.out.println("无法写入文件："+ioe.getMessage());

}

10.读取文件属性

//import java.io.*;

// 文件属性的取得

File af = new File(%%1);

if (af.exists()) {

System.out.println(f.getName() + "的属性如下： 文件长度为：" + f.length());

System.out.println(f.isFile() ? "是文件" : "不是文件");

System.out.println(f.isDirectory() ? "是目录" : "不是目录");

System.out.println(f.canRead() ? "可读取" : "不");

System.out.println(f.canWrite() ? "是隐藏文件" : "");

System.out.println("文件夹的最后修改日期为：" + new Date(f.lastModified()));

} else {

System.out.println(f.getName() + "的属性如下：");

System.out.println(f.isFile() ? "是文件" : "不是文件");

System.out.println(f.isDirectory() ? "是目录" : "不是目录");

System.out.println(f.canRead() ? "可读取" : "不");

System.out.println(f.canWrite() ? "是隐藏文件" : "");

System.out.println("文件的最后修改日期为：" + new Date(f.lastModified()));

}

if(f.canRead()){

%%2

}

if(f.canWrite()){

%%3

}

11.写入属性

//import java.io.*;

File filereadonly=new File(%%1);

try {

boolean b=filereadonly.setReadOnly();

}

catch (Exception e) {

System.out.println("拒绝写访问："+e.printStackTrace());

}

12.枚举一个文件夹中的所有文件

//import java.io.*;

//import java.util.*;

LinkedListString folderList = new LinkedListString();

folderList.add(%%1);

while (folderList.size() 0) {

File file = new File(folderList.peek());

folderList.removeLast();

File[] files = file.listFiles();

ArrayListFile fileList = new ArrayListFile();

for (int i = 0; i files.length; i++) {

if (files[i].isDirectory()) {

folderList.add(files[i].getPath());

} else {

fileList.add(files[i]);

}

}

for (File f : fileList) {

%%2=f.getAbsoluteFile();

%%3

}

}

13.复制文件夹

//import java.io.*;

//import java.util.*;

LinkedListString folderList = new LinkedListString();

folderList.add(%%1);

LinkedListString folderList2 = new LinkedListString();

folderList2.add(%%2+ %%1.substring(%%1.lastIndexOf("\\")));

while (folderList.size() 0) {

(new File(folderList2.peek())).mkdirs(); // 如果文件夹不存在 则建立新文件夹

File folders = new File(folderList.peek());

String[] file = folders.list();

File temp = null;

try {

for (int i = 0; i file.length; i++) {

if (folderList.peek().endsWith(File.separator)) {

temp = new File(folderList.peek() + File.separator

+ file[i]);

} else {

temp = new File(folderList.peek() + File.separator

+ file[i]);

}

if (temp.isFile()) {

FileInputStream input = new FileInputStream(temp);

FileOutputStream output = new FileOutputStream(

folderList2.peek() + File.separator

+ (temp.getName()).toString());

byte[] b = new byte[5120];

int len;

while ((len = input.read(b)) != -1) {

output.write(b, 0, len);

}

output.flush();

output.close();

input.close();

}

if (temp.isDirectory()) {// 如果是子文件夹

for (File f : temp.listFiles()) {

if (f.isDirectory()) {

folderList.add(f.getPath());

folderList2.add(folderList2.peek()

+ File.separator + f.getName());

}

}

}

}

} catch (Exception e) {

//System.out.println("复制整个文件夹内容操作出错");

e.printStackTrace();

}

folderList.removeFirst();

folderList2.removeFirst();

}

14.复制一个文件夹下所有的文件夹到另一个文件夹下

//import java.io.*;

//import java.util.*;

File copyfolders=new File(%%1);

File[] copyfoldersList=copyfolders.listFiles();

for(int k=0;kcopyfoldersList.length;k++){

if(copyfoldersList[k].isDirectory()){

ArrayListStringfolderList=new ArrayListString();

folderList.add(copyfoldersList[k].getPath());

ArrayListStringfolderList2=new ArrayListString();

folderList2.add(%%2+"/"+copyfoldersList[k].getName());

for(int j=0;jfolderList.length;j++){

(new File(folderList2.get(j))).mkdirs(); //如果文件夹不存在 则建立新文件夹

File folders=new File(folderList.get(j));

String[] file=folders.list();

File temp=null;

try {

for (int i = 0; i file.length; i++) {

if(folderList.get(j).endsWith(File.separator)){

temp=new File(folderList.get(j)+"/"+file[i]);

}

else{

temp=new File(folderList.get(j)+"/"+File.separator+file[i]);

}

FileInputStream input = new FileInputStream(temp);

if(temp.isFile()){

FileInputStream input = new FileInputStream(temp);

FileOutputStream output = new FileOutputStream(folderList2.get(j) + "/" +

(temp.getName()).toString());

byte[] b = new byte[5120];

int len;

while ( (len = input.read(b)) != -1) {

output.write(b, 0, len);

}

output.flush();

output.close();

input.close();

}

if(temp.isDirectory()){//如果是子文件夹

folderList.add(folderList.get(j)+"/"+file[i]);

folderList2.add(folderList2.get(j)+"/"+file[i]);

}

}

}

catch (Exception e) {

System.out.println("复制整个文件夹内容操作出错");

e.printStackTrace();

}

}

}

}

15.移动文件夹

//import java.io.*;

//import java.util.*;

LinkedListString folderList = new LinkedListString();

folderList.add(%%1);

LinkedListString folderList2 = new LinkedListString();

folderList2.add(%%2 + %%1.substring(%%1.lastIndexOf("\\")));

while (folderList.size() 0) {

(new File(folderList2.peek())).mkdirs(); // 如果文件夹不存在 则建立新文件夹

File folders = new File(folderList.peek());

String[] file = folders.list();

File temp = null;

try {

for (int i = 0; i file.length; i++) {

if (folderList.peek().endsWith(File.separator)) {

temp = new File(folderList.peek() + File.separator

+ file[i]);

} else {

temp = new File(folderList.peek() + File.separator

+ file[i]);

}

if (temp.isFile()) {

FileInputStream input = new FileInputStream(temp);

FileOutputStream output = new FileOutputStream(

folderList2.peek() + File.separator

+ (temp.getName()).toString());

byte[] b = new byte[5120];

int len;

while ((len = input.read(b)) != -1) {

output.write(b, 0, len);

}

output.flush();

output.close();

input.close();

if (!temp.delete())

System.out.println("删除单个文件操作出错!");

}

if (temp.isDirectory()) {// 如果是子文件夹

for (File f : temp.listFiles()) {

if (f.isDirectory()) {

folderList.add(f.getPath());

folderList2.add(folderList2.peek()

+ File.separator + f.getName());

}

}

}

}

} catch (Exception e) {

// System.out.println("复制整个文件夹内容操作出错");

e.printStackTrace();

}

folderList.removeFirst();

folderList2.removeFirst();

}

File f = new File(%%1);

if (!f.delete()) {

for (File file : f.listFiles()) {

if (file.list().length == 0) {

System.out.println(file.getPath());

file.delete();

}

}

}

16.移动一个文件夹下所有的文件夹到另一个目录下

//import java.io.*;

//import java.util.*;

File movefolders=new File(%%1);

File[] movefoldersList=movefolders.listFiles();

for(int k=0;kmovefoldersList.length;k++){

if(movefoldersList[k].isDirectory()){

ArrayListStringfolderList=new ArrayListString();

folderList.add(movefoldersList[k].getPath());

ArrayListStringfolderList2=new ArrayListString();

folderList2.add(%%2+"/"+movefoldersList[k].getName());

for(int j=0;jfolderList.length;j++){

(new File(folderList2.get(j))).mkdirs(); //如果文件夹不存在 则建立新文件夹

File folders=new File(folderList.get(j));

String[] file=folders.list();

File temp=null;

try {

for (int i = 0; i file.length; i++) {

if(folderList.get(j).endsWith(File.separator)){

temp=new File(folderList.get(j)+"/"+file[i]);

}

else{

temp=new File(folderList.get(j)+"/"+File.separator+file[i]);

}

FileInputStream input = new FileInputStream(temp);

if(temp.isFile()){

FileInputStream input = new FileInputStream(temp);

FileOutputStream output = new FileOutputStream(folderList2.get(j) + "/" +

(temp.getName()).toString());

byte[] b = new byte[5120];

int len;

while ( (len = input.read(b)) != -1) {

output.write(b, 0, len);

}

output.flush();

output.close();

input.close();

temp.delete();

}

if(temp.isDirectory()){//如果是子文件夹

folderList.add(folderList.get(j)+"/"+file[i]);

folderList2.add(folderList2.get(j)+"/"+file[i]);

}

}

}

catch (Exception e) {

System.out.println("复制整个文件夹内容操作出错");

e.printStackTrace();

}

}

movefoldersList[k].delete();

}

}

17.以一个文件夹的框架在另一个目录创建文件夹和空文件

//import java.io.*;

//import java.util.*;

boolean b=false;//不创建空文件

ArrayListStringfolderList=new ArrayListString();

folderList.add(%%1);

ArrayListStringfolderList2=new ArrayListString();

folderList2.add(%%2);

for(int j=0;jfolderList.length;j++){

(new File(folderList2.get(j))).mkdirs(); //如果文件夹不存在 则建立新文件夹

File folders=new File(folderList.get(j));

String[] file=folders.list();

File temp=null;

try {

for (int i = 0; i file.length; i++) {

if(folderList.get(j).endsWith(File.separator)){

temp=new File(folderList.get(j)+"/"+file[i]);

}

else{

temp=new File(folderList.get(j)+"/"+File.separator+file[i]);

}

FileInputStream input = new FileInputStream(temp);

if(temp.isFile()){

if (b) temp.createNewFile();

}

if(temp.isDirectory()){//如果是子文件夹

folderList.add(folderList.get(j)+"/"+file[i]);

folderList2.add(folderList2.get(j)+"/"+file[i]);

}

}

}

catch (Exception e) {

System.out.println("复制整个文件夹内容操作出错");

e.printStackTrace();

}

}

18.复制文件

//import java.io.*;

int bytesum = 0;

int byteread = 0;

File oldfile = new File(%%1);

try {

if (oldfile.exists()) { //文件存在时

FileInputStream inStream = new FileInputStream(oldfile); //读入原文件

FileOutputStream fs = new FileOutputStream(new File(%%2,oldfile.getName()));

byte[] buffer = new byte[5120];

int length;

while ( (byteread = inStream.read(buffer)) != -1) {

bytesum += byteread; //字节数 文件大小

System.out.println(bytesum);

fs.write(buffer, 0, byteread);

}

inStream.close();

}

}

catch (Exception e) {

System.out.println("复制单个文件操作出错");

e.printStackTrace();

}

19.复制一个文件夹下所有的文件到另一个目录

//import java.io.*;

File copyfiles=new File(%%1);

File[] files=copyfiles.listFiles();

for(int i=0;ifiles.length;i++){

if(!files[i].isDirectory()){

int bytesum = 0;

int byteread = 0;

try {

InputStream inStream = new FileInputStream(files[i]); //读入原文件

FileOutputStream fs = new FileOutputStream(new File(%%2,files[i].getName());

byte[] buffer = new byte[5120];

int length;

while ( (byteread = inStream.read(buffer)) != -1) {

bytesum += byteread; //字节数 文件大小

System.out.println(bytesum);

fs.write(buffer, 0, byteread);

}

inStream.close();

} catch (Exception e) {

System.out.println("复制单个文件操作出错");

e.printStackTrace();

}

}

}

20.提取扩展名

String %%2=%%1.substring(%%1.lastIndexOf(".")+1);