任務管理器案例

1.單例類

package Singleton;/*** Created by Jim on 2016/9/28.*/ public class TaskManager {private static TaskManager tm = null;private TaskManager() {System.out.println("創建任務管理器");}public void displayProcesses() {System.out.println("顯示進程");}public void displayServices() {System.out.println("顯示服務");}public static TaskManager getInstance() {if (tm == null) {tm = new TaskManager();}return tm;}}

2.客戶端

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());}} }

身份證辦理案例

1.單例類

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("第一次辦理身份證，分配新號碼！");instance=new IdentityCardNo();instance.setIdentityCardNo("No400011112222");}else{System.out.println("重復辦理身份證，獲取舊號碼！");}return instance;}private void setIdentityCardNo(String no){this.no=no;}public String getIdentityCardNo(){return this.no;} }

2.客戶端類

package Singleton;public class Client {public static void main(String args[]){try{IdentityCardNo no1,no2;no1=IdentityCardNo.getInstance();no2=IdentityCardNo.getInstance();System.out.println("身份證號碼是否一致：" + (no1==no2));String str1,str2;str1=no1.getIdentityCardNo();str2=no1.getIdentityCardNo();System.out.println("第一次號碼：" + str1);System.out.println("第二次號碼：" + str2);System.out.println("內容是否相等：" + str1.equalsIgnoreCase(str2));System.out.println("是否是相同對象：" + (str1==str2));}catch(Exception e){System.out.println(e.getMessage());}} }

執行結果：

第一次辦理身份證，分配新號碼！
重復辦理身份證，獲取舊號碼！
身份證號碼是否一致：true
第一次號碼：No400011112222
第二次號碼：No400011112222
內容是否相等：true
是否是相同對象：true

打印池

1.打印池類

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("創建打印池！");instance=new PrintSpoolerSingleton();}else{throw new PrintSpoolerException("打印池正在工作中！");}return instance;}public void manageJobs(){System.out.println("管理打印任務！");} }

2.異常輔助類

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

3.客戶端類

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());}} }

執行結果：

創建打印池！
管理打印任務！
--------------------------
打印池正在工作中！

轉載于:https://www.cnblogs.com/jiqing9006/p/5918556.html

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