任务管理器案例

1.单例类

package Singleton;/** * Created by Jim on 2016/9/28. */public class TaskManager {    private static TaskManager tm = null;    private TaskManager() {        System.out.println("创建任务管理器");    }    public void displayProcesses() {        System.out.println("显示进程");    }    public void displayServices() {        System.out.println("显示服务");    }    public static TaskManager getInstance() {        if (tm == null) {            tm = new TaskManager();        }        return tm;    }}

2.客户端

package Singleton;public class Client{    public static void main(String args[])    {         try         {             TaskManager tm = TaskManager.getInstance();             tm.displayProcesses();             tm.displayServices();             TaskManager tm2 = TaskManager.getInstance();             tm2.displayProcesses();             tm2.displayServices();         }         catch(Exception e)         {            System.out.println(e.getMessage());         }    }}

身份证办理案例

1.单例类

package Singleton;/** * Created by e550 on 2016/9/29. */public class IdentityCardNo {    private static IdentityCardNo instance=null;    private String no;    private IdentityCardNo()    {    }    public static IdentityCardNo getInstance()    {        if(instance==null)        {            System.out.println("第一次办理身份证，分配新号码！");            instance=new IdentityCardNo();            instance.setIdentityCardNo("No400011112222");        }        else        {            System.out.println("重复办理身份证，获取旧号码！");        }        return instance;    }    private void setIdentityCardNo(String no)    {        this.no=no;    }    public String getIdentityCardNo()    {        return this.no;    }}

2.客户端类

package Singleton;public class Client{    public static void main(String args[])    {         try         {             IdentityCardNo no1,no2;             no1=IdentityCardNo.getInstance();             no2=IdentityCardNo.getInstance();             System.out.println("身份证号码是否一致：" + (no1==no2));             String str1,str2;             str1=no1.getIdentityCardNo();             str2=no1.getIdentityCardNo();             System.out.println("第一次号码：" + str1);             System.out.println("第二次号码：" + str2);             System.out.println("内容是否相等：" + str1.equalsIgnoreCase(str2));             System.out.println("是否是相同对象：" + (str1==str2));         }         catch(Exception e)         {            System.out.println(e.getMessage());         }    }}

执行结果：

第一次办理身份证，分配新号码！

重复办理身份证，获取旧号码！

身份证号码是否一致：true

第一次号码：No400011112222

第二次号码：No400011112222

内容是否相等：true

是否是相同对象：true

打印池

1.打印池类

package SpoolerSingleton;public class PrintSpoolerSingleton{    private static PrintSpoolerSingleton instance=null; // 打印池    private PrintSpoolerSingleton()    {    }    public static PrintSpoolerSingleton getInstance() throws PrintSpoolerException    {        if(instance==null)        {            System.out.println("创建打印池！");            instance=new PrintSpoolerSingleton();        }        else        {            throw new PrintSpoolerException("打印池正在工作中！");        }        return instance;    }    public void manageJobs()    {        System.out.println("管理打印任务！");    }}

2.异常辅助类

package SpoolerSingleton;public class PrintSpoolerException extends Exception{    public PrintSpoolerException(String message)    {        super(message);    }}

3.客户端类

package SpoolerSingleton;public class Client{    public static void main(String a[])    {        PrintSpoolerSingleton ps1,ps2;        try        {            ps1=PrintSpoolerSingleton.getInstance();            ps1.manageJobs();        }        catch(PrintSpoolerException e)        {            System.out.println(e.getMessage());        }        System.out.println("--------------------------");        try        {            ps2=PrintSpoolerSingleton.getInstance();            ps2.manageJobs();        }        catch(PrintSpoolerException e)        {            System.out.println(e.getMessage());        }    }}

执行结果：

创建打印池！

管理打印任务！

--------------------------

打印池正在工作中！

本文转自TBHacker博客园博客，原文链接：http://www.cnblogs.com/jiqing9006/p/5918556.html，如需转载请自行联系原作者