5个JAVA入门必看的经典实例

入门必看的5个JAVA经典实例，供大家参考，具体内容如下

1.一个饲养员给动物喂食物的例子体现JAVA中的面向对象思想,接口（抽象类）的用处

package com.softeem.demo;
/**
*@author leno
*动物的接口
*/

interface Animal {
 public void eat(Food food);

}

/**
*@author leno
*一种动物类:猫
*/
class Cat implements Animal {
 public void eat(Food food) {
  System.out.println("小猫吃" + food.getName());

 }
}
/**
*@author leno
*一种动物类:狗
*/

class Dog implements Animal {
 public void eat(Food food) {
  System.out.println("小狗啃" + food.getName());
 }

}

/**
*@author leno
*食物抽象类
*/

abstract class Food {
 protected String name;
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }

}

/**
*@author leno
*一种食物类:鱼
*/

class Fish extends Food {
 public Fish(String name) {
  this.name = name;
 }

}

/**
*@author leno
*一种食物类:骨头
*/
class Bone extends Food {
 public Bone(String name) {
  this.name = name;

 }
}

/**
*@author leno
*饲养员类
*
*/
class Feeder {

 /**
  *饲养员给某种动物喂某种食物
  *@param animal
  *@param food
  */

 public void feed(Animal animal, Food food) {
  animal.eat(food);
 }

}
/**
*@author leno
*测试饲养员给动物喂食物
*/

public class TestFeeder {
 public static void main(String[] args) {
  Feeder feeder = new Feeder();
  Animal animal = new Dog();
  Food food = new Bone("肉骨头");
  feeder.feed(animal, food); //给狗喂肉骨头
   animal = new Cat();
  food = new Fish("鱼");

  feeder.feed(animal, food); //给猫喂鱼

 }

}

2.做一个单子模式的类，只加载一次属性文件

package com.softeem.demo;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
/**
* @authorleno 单子模式，保证在整个应用期间只加载一次配置属性文件
*/

public class Singleton {
 private static Singleton instance;
 private static final String CONFIG_FILE_PATH = "E:\\config.properties";
 private Properties config;
 private Singleton() {
  config = new Properties();
  InputStream is;
  try {
   is = new FileInputStream(CONFIG_FILE_PATH);
   config.load(is);
   is.close();
  } catch (FileNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }

 }

 public static Singleton getInstance() {
  if (instance == null) {
   instance = new Singleton();
  }
  return instance;
 }
 public Properties getConfig() {
  return config;

 }

 public void setConfig(Properties config) {

  this.config = config;

 }

}

3.用JAVA中的多线程示例银行取款问题

package com.softeem.demo;

/**
*@author leno
*账户类
*默认有余额，可以取款
*/

class Account {
 private float balance = 1000;
 public float getBalance() {
  return balance;
 }

 public void setBalance(float balance) {
  this.balance = balance;
 }
 /**
  *取款的方法需要同步
  *@param money
  */
 public synchronized void withdrawals(float money) {
  if (balance >= money) {
   System.out.println("被取走" + money + "元!");
   try {
    Thread.sleep(1000);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   balance -= money;
  } else {
   System.out.println("对不起,余额不足!");
  }
 }
}
/**
*@author leno
*银行卡
*/

class TestAccount1 extends Thread {

 private Account account;
 public TestAccount1(Account account) {
  this.account = account;
 }
 @Override
 public void run() {
  account.withdrawals(800);
  System.out.println("余额为:" + account.getBalance() + "元!");

 }

}

/**
*@authorleno
*存折
*/

class TestAccount2 extends Thread {
 private Account account;
 public TestAccount2(Account account) {
  this.account = account;
 }

 @Override
 public void run() {
  account.withdrawals(700);
  System.out.println("余额为:" + account.getBalance() + "元!");
 }

}

public class Test {

 public static void main(String[] args) {
  Account account = new Account();
  TestAccount1 testAccount1 = new TestAccount1(account);
  testAccount1.start();
  TestAccount2 testAccount2 = new TestAccount2(account);
  testAccount2.start();

 }

}

4.用JAVA中的多线程示例生产者和消费者问题

package com.softeem.demo;
class Producer implements Runnable {
 private SyncStack stack;
 public Producer(SyncStack stack) {
  this.stack = stack;

 }

 public void run() {

  for (int i = 0; i < stack.getProducts().length; i++) {

   String product = "产品" + i;
   stack.push(product);
   System.out.println("生产了: " + product);
   try {
    Thread.sleep(200);
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
  }

 }

}

class Consumer implements Runnable {
 private SyncStack stack;
 public Consumer(SyncStack stack) {
  this.stack = stack;
 }
 public void run() {
  for (int i = 0; i < stack.getProducts().length; i++) {
   String product = stack.pop();
   System.out.println("消费了: " + product);
   try {
    Thread.sleep(1000);
   } catch (InterruptedException e) {
    e.printStackTrace();

   }

  }

 }

}

class SyncStack {
 private String[] products = new String[10];
 private int index;
 public synchronized void push(String product) {
  if (index == product.length()) {
   try {
    wait();
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();

   }

  }

  notify();
  products[index] = product;
  index++;

 }

 public synchronized String pop() {
  if (index == 0) {
   try {
    wait();
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

  }
  notify();
  index--;
  String product = products[index];
  return product;

 }
 public String[] getProducts() {
  return products;
 }

}
public class TestProducerConsumer {
 public static void main(String[] args) {
  SyncStack stack = new SyncStack();
  Producer p = new Producer(stack);
  Consumer c = new Consumer(stack);
  new Thread(p).start();
  new Thread(c).start();

 }

}

5.编程实现序列化的Student（sno,sname）对象在网络上的传输

package com.softeem.demo;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.net.ServerSocket;
import java.net.Socket;
class Student implements Serializable {
 private int sno;
 private String sname;
 public Student(int sno, String sname) {
  this.sno = sno;
  this.sname = sname;

 }

 public int getSno() {
  return sno;

 }

 public void setSno(int sno) {
  this.sno = sno;

 }

 public String getSname() {
  return sname;

 }

 public void setSname(String sname) {
  this.sname = sname;
 }

 @Override

 public String toString() {
  return "学号:" + sno + ";姓名:" + sname;

 }

}
class MyClient extends Thread {
 @Override

 public void run() {
  try {
   Socket s = new Socket("localhost", 9999);
   ObjectInputStream ois = new ObjectInputStream(s.getInputStream());
   Student stu = (Student) ois.readObject();
   String msg = "客户端程序收到服务器端程序传输过来的学生对象>> " + stu;
   System.out.println(msg);
   ois.close();
   s.close();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();

  } catch (ClassNotFoundException e) {
   // TODO Auto-generated catch block

   e.printStackTrace();

  }

 }

}

class MyServer extends Thread {
 @Override
 public void run() {

  try {
   ServerSocket ss = new ServerSocket(9999);
   Socket s = ss.accept();
   ObjectOutputStream ops = new ObjectOutputStream(s.getOutputStream());
   Student stu = new Student(1, "赵本山");
   ops.writeObject(stu);
   ops.close();
   s.close();
   ss.close();

  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();

  }

 }

}

public class TestTransfer {
 public static void main(String[] args) {
  new MyServer().start();
  new MyClient().start();

 }

}

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