中等规模java程序代码 中等规模java程序代码怎么写

求java经典小程序代码

代码如下：

public class HelloWorld {

  public static void main(String []args) {

int a = 3, b = 7 ;

         System.out.println("Hello World!");

  }

public static int f(int a, int b){

     return a*a + a*b + b*b;

}

}

结果如下：

相关问答

Q1: 求编写一个超级简单的Java的程序源代码

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

class ConstructFrame extends JFrame

{

private static final long serialVersionUID = 1L;

String value1="",result,value2="";

int flag=0,fix=0,sum=1;

Boolean happy;

JTextField text=new JTextField(30);

int flagsum=0;

Container c=getContentPane();

JButton buttonx;

ConstructFrame()

{ super("计算器");

c.setLayout(null);

c.setBackground(Color.blue);

this.setSize(400, 400);

c.add(text);

text.setHorizontalAlignment(JTextField.RIGHT);

final JButton buttonx=new JButton("BackSpace");

c.add(buttonx);

buttonx.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

int count=0;

String temp;

if(flag==0)

{

count=value1.length();

if(count!=1)

temp=value1.substring(0, count-1);

else

temp="0";

value1=temp;

}

else

{

count=value2.length();

if(count!=1)

temp=value2.substring(0, count-1);

else

temp="0";

value2=temp;

}

text.setText(temp);

}

});

final JButton buttony=new JButton("CE");

c.add(buttony);

buttony.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

value1="";

value2="";

flag=0;

text.setText("0");

}

});

final JButton button1=new JButton("1");

c.add(button1);

button1.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+1;

temp=value1;

}

else

{

value2=value2+1;

temp=value2;

}

text.setText(temp);

}

});

final JButton button2=new JButton(" 2 ");

c.add(button2);

button2.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+2;

temp=value1;

}

else

{

value2=value2+2;

temp=value2;

}

text.setText(temp);

}

});

final JButton button3=new JButton("3");

c.add(button3);

button3.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+3;

temp=value1;

}

else

{

value2=value2+3;

temp=value2;

}

text.setText(temp);

}

});

final JButton button4=new JButton("4");

c.add(button4);

button4.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+4;

temp=value1;

}

else

{

value2=value2+4;

temp=value2;

}

text.setText(temp);

}

});

final JButton button5=new JButton("5");

c.add(button5);

button5.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+5;

temp=value1;

}

else

{

value2=value2+5;

temp=value2;

}

text.setText(temp);

}

});

final JButton button6=new JButton("6");

c.add(button6);

button6.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+6;

temp=value1;

}

else

{

value2=value2+6;

temp=value2;

}

text.setText(temp);

}

});

final JButton button7=new JButton("7");

c.add(button7);

button7.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+7;

temp=value1;

}

else

{

value2=value2+7;

temp=value2;

}

text.setText(temp);

}

});

final JButton button8=new JButton("8");

c.add(button8);

button8.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+8;

temp=value1;

}

else

{

value2=value2+8;

temp=value2;

}

text.setText(temp);

}

});

final JButton button9=new JButton("9");

c.add(button9);

button9.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+9;

temp=value1;

}

else

{

value2=value2+9;

temp=value2;

}

text.setText(temp);

}

});

final JButton button0=new JButton("0");

c.add(button0);

button0.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

String temp;

if(flag==0)

{

value1=value1+0;

temp=value1;

}

else

{

value2=value2+0;

temp=value2;

}

text.setText(temp);

}

});

final JButton buttonadd=new JButton(" + ");

c.add(buttonadd);

buttonadd.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

flag=1;

fix=1;

flagsum=0;

}

});

final JButton buttonsubtract=new JButton(" - ");

c.add(buttonsubtract);

buttonsubtract.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

flag=1;

fix=2;

flagsum=0;

}

});

final JButton buttoncheng=new JButton(" * ");

c.add(buttoncheng);

buttoncheng.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

flag=1;

fix=3;

flagsum=0;

}

});

final JButton buttonchu=new JButton(" / ");

c.add(buttonchu);

buttonchu.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

flag=1;

flagsum=0;

fix=4;

}

});

final JButton buttonequal=new JButton(" = ");

c.add(buttonequal);

buttonequal.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{

double temp1,temp2;

double temp=0;

flagsum=0;

temp1=Double.parseDouble(value1);

temp2=Double.parseDouble(value2);

flag=0;

switch(fix)

{

case 1: temp=temp1+temp2;break;

case 2: temp=temp1-temp2;break;

case 3: temp=temp1*temp2;break;

case 4: temp=temp1/temp2;break;

}

result=Double.valueOf(temp).toString();

value1=result;

value2="";

flag=1;

text.setText(result);

}

});

final JButton buttonpoint=new JButton(".");

c.add(buttonpoint);

buttonpoint.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{ if(flagsum==0)

{

String temp;

if(flag==0 )

{

value1=value1+".";

temp=value1;

}

else

{

value2=value2+".";

temp=value2;

}

flagsum=1;

text.setText(temp);

}

}

});

JButton buttonz=new JButton("Start");

c.add(buttonz);

buttonz.addMouseListener(new MouseAdapter()

{

public void mousePressed(MouseEvent e)

{ if(sum%2==1)

{

happy=true;

text.setText("0.");

flag=0;

}

else

{

happy=false;

value1="";

value2="";

text.setText("");

}

text.setEnabled(happy);

button1.setEnabled(happy);

button2.setEnabled(happy);

button3.setEnabled(happy);

button4.setEnabled(happy);

button5.setEnabled(happy);

button6.setEnabled(happy);

button7.setEnabled(happy);

button8.setEnabled(happy);

button9.setEnabled(happy);

button0.setEnabled(happy);

buttonx.setEnabled(happy);

buttony.setEnabled(happy);

buttonadd.setEnabled(happy);

buttonsubtract.setEnabled(happy);

buttonpoint.setEnabled(happy);

buttonequal.setEnabled(happy);

buttoncheng.setEnabled(happy);

buttonchu.setEnabled(happy);

sum++;

}

});

button1.setEnabled(false);

button2.setEnabled(false);

button3.setEnabled(false);

button4.setEnabled(false);

button5.setEnabled(false);

button6.setEnabled(false);

button7.setEnabled(false);

button8.setEnabled(false);

button9.setEnabled(false);

button0.setEnabled(false);

buttonx.setEnabled(false);

buttony.setEnabled(false);

buttonadd.setEnabled(false);

buttonsubtract.setEnabled(false);

buttonpoint.setEnabled(false);

buttonequal.setEnabled(false);

buttoncheng.setEnabled(false);

buttonchu.setEnabled(false);

text.setEnabled(false);

text.setBounds(20, 20, 200, 40);

buttonx.setBounds(20, 60,100, 40);

buttony.setBounds(140, 60,100, 40);

buttonz.setBounds(260, 60,80, 40);

button1.setBounds(20, 120,60, 40);

button2.setBounds(100, 120,60, 40);

button3.setBounds(180, 120,60, 40);

buttonadd.setBounds(260, 120,60, 40);

button4.setBounds(20, 180,60, 40);

button5.setBounds(100, 180,60, 40);

button6.setBounds(180, 180,60, 40);

buttonsubtract.setBounds(260, 180,60, 40);

button7.setBounds(20, 240,60, 40);

button8.setBounds(100, 240,60, 40);

button9.setBounds(180, 240,60, 40);

buttoncheng.setBounds(260,240,60,40);

button0.setBounds(20, 300,60, 40);

buttonpoint.setBounds(100, 300, 60, 40);

buttonequal.setBounds(180,300,60, 40);

buttonchu.setBounds(260, 300,60, 40);

setVisible(true);

}

class MYMouseEvent extends MouseAdapter

{

public void mousePressed(MouseEvent e)

{

value1=e.toString();

text.setText(value1);

}

}

}

class Calutator

{

public static void main(String[] args)

{

new ConstructFrame();

}

}

你自己慢慢的看吧！

Q2: 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();

}

}

Q3: 求大神用Java编写出这个程序，要有具体代码，万分感激，定采纳

按照你的要求编写的JavaGUI程序如下：

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JTextField;

public class HH extends JFrame implements ActionListener{

 JPanel jp1=new JPanel();

 JPanel jp2=new JPanel();

 JPanel jp3=new JPanel();

 JTextField jtf=new JTextField(20);

 JButton jb1=new JButton("显示");

 JButton jb2=new JButton("清除");

 HH(){

  jb1.addActionListener(this);

  jb2.addActionListener(this);

  jp1.setLayout(new GridLayout(2,1));

  jp3.add(jtf);

  jp2.add(jb1);jp2.add(jb2);

  jp1.add(jp3);jp1.add(jp2);

  getContentPane().add(jp1);

  setSize(300, 120);

  setLocationRelativeTo(null);

  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

  setVisible(true);

 }

 @Override

 public void actionPerformed(ActionEvent e) {

  if(e.getSource()==jb1){

   jtf.setText("java程序设计");

  }

  if(e.getSource()==jb2){

   jtf.setText("");

  }

 }

 public static void main(String[] args) {

  new HH();

 }

}

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