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();

 }

}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。