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;interface Animal { public void eat(Food food);}class Cat implements Animal { public void eat(Food food) { System.out.println("小猫吃" + food.getName()); }}class Dog implements Animal { public void eat(Food food) { System.out.println("小狗啃" + food.getName()); }}abstract class Food { protected String name; public String getName() { return name; } public void setName(String name) { this.name = name; }}class Fish extends Food { public Fish(String name) { this.name = name; }}class Bone extends Food { public Bone(String name) { this.name = name; }}class Feeder { public void feed(Animal animal, Food food) { animal.eat(food); }}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;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;class Account { private float balance = 1000; public float getBalance() { return balance; } public void setBalance(float balance) { this.balance = balance; } 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!"); } }}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!"); }}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(); }}
11.写一个方法，用一个for循环打印九九乘法表 publicvoid nineNineMultiTable() { for (int i = 1,j = 1; j <= 9; i++) { System.out.print(i+"*"+j+"="+i*j+" "); if(i==j) { i=0; j++; System.out.println(); } } }12.给定一个java.util.Date对象，如何转化为”2007-3-22 20:23:22”格式的字符串 public String dateToStr(java.util.Date date) { SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String str = sdf.format(date); return str; }13.写一个方法，能够判断任意一个整数是否素数 publicboolean isPrimes(int n) { for (int i = 2; i <= Math.sqrt(n); i++) { if(n%i==0) { returnfalse; } } returntrue; }14.写一个方法，输入任意一个整数，返回它的阶乘 publicint factorial(int n) { //递归 if(n==1) { return 1; } return n*factorial(n-1); //非递归// int multi = 1;// for (int i = 2; i <= n; i++) {// multi*=i;// }// return multi; }15.写一个方法，用二分查找法判断任意整数在任意整数数组里面是否存在，若存在就返回它在数组中的索引位置，不存在返回-1 publicint binarySearch(int[] dataset,int data,int beginIndex,int endIndex) { int midIndex = (beginIndex+endIndex)/2; if(data<dataset[beginIndex]||data>dataset[endIndex]||beginIndex>endIndex)return -1; if(data<dataset[midIndex]) { return binarySearch(dataset,data,beginIndex,midIndex-1); }elseif(data>dataset[midIndex]) { return binarySearch(dataset,data,midIndex+1,endIndex); }else { return midIndex; } } publicint binarySearch(int[] dataset ,int data) { int beginIndex = 0; int endIndex = dataset.length - 1; int midIndex = -1; if(data<dataset[beginIndex]||data>dataset[endIndex]||beginIndex>endIndex)return -1; while(beginIndex <= endIndex) { midIndex = (beginIndex+endIndex)/2; if(data<dataset[midIndex]) { endIndex = midIndex-1; } elseif(data>dataset[midIndex]) { beginIndex = midIndex+1; }else { return midIndex; } } return -1; }
转载于:https://www.cnblogs.com/liuzhuqing/archive/2012/07/13/7480785.html
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