线程:suspend与resume方法
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线程:suspend与resume方法
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suspend方法的缺點(diǎn)一:?
? ?該方法很容易造成公共的同步對(duì)象的獨(dú)占,使得其他線程無法訪問公共同步對(duì)象。
? ??
public class Run {public static void main(String[] args){try{final SynchronizedObject2 object = new SynchronizedObject2();Thread thread1 = new Thread(){@Overridepublic void run(){object.printString();}};thread1.setName("a");thread1.start();Thread.sleep(1000);Thread thread2 = new Thread(){@Overridepublic void run(){System.out.println("thread2啟動(dòng)了,但進(jìn)入不了printString()方法! 只打印了1個(gè)begin ");System.out.println(" 因?yàn)閜rintString()方法被a線程鎖定并且永遠(yuǎn)suspend暫停了! ");object.printString();}};thread2.start();}catch(InterruptedException e){e.printStackTrace();}}public static void main1(String[] args){try {MyThread12 thread = new MyThread12();thread.start();Thread.sleep(5000);// A段thread.suspend();System.out.println("A="+System.currentTimeMillis()+" i="+thread.getI());Thread.sleep(5000);System.out.println("A="+System.currentTimeMillis()+" i="+thread.getI());// B段thread.resume();Thread.sleep(5000);// C段thread.suspend();System.out.println("A="+System.currentTimeMillis()+" i="+thread.getI());Thread.sleep(5000);System.out.println("A="+System.currentTimeMillis()+" i="+thread.getI());} catch (InterruptedException e) {e.printStackTrace();}} }public class SynchronizedObject2 {synchronized public void printString(){System.out.println("begin");if(Thread.currentThread().getName().equals("a")){System.out.println("a 線程永遠(yuǎn) suspend了 !");Thread.currentThread().suspend();}System.out.println("end");} }suspend方法的缺點(diǎn)二:
? ?可能會(huì)出現(xiàn)線程的暫停,導(dǎo)致數(shù)據(jù)不同步
public class Run2 {public static void main(String[] args){try{final MyObject object = new MyObject();Thread thread1 = new Thread(){@Overridepublic void run(){object.setValue("a", "aa");}};thread1.setName("a");thread1.start();Thread.sleep(500);Thread thread2 = new Thread(){@Overridepublic void run(){object.printUsernamePassword();}};thread2.start();}catch(InterruptedException e){e.printStackTrace();}} }public class MyObject {private String username = "1";private String password = "11";public void setValue(String u, String p){this.username = u;if(Thread.currentThread().getName().equals("a")){System.out.println("停止a線程");Thread.currentThread().suspend();}this.password = p;}public void printUsernamePassword(){System.out.println(username + " " + password);} }?
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