这两个方法使用不当，容易造成公共的同步对象的独占，使得其他线程无法访问公共的同步对象
测试
package com.cky.bean; /**
* Created by edison on 2017/12/3.
*/
public class SynchroObject{ synchronized public void printString() {
System.out.println("begin");
if (Thread.currentThread().getName().equals("a")) {
System.out.println("a线程永远suspend");
Thread.currentThread().suspend();
}
System.out.println("end");
}
}
package com.cky.test; import com.cky.bean.SynchroObject; /**
* Created by edison on 2017/12/3.
*/
public class Run {
public static void main(String[] args) {
try {
final SynchroObject so = new SynchroObject();
Thread th1 = new Thread() {
@Override
public void run() {
so.printString();
}
};
th1.setName("a");
th1.start();
Thread.sleep(2000);
Thread th2 = new Thread() {
@Override
public void run() {
System.out.println("thread2线程启动了，但是不能进入println方法，因为线程已经被a锁定且暂停");
so.printString();
}
};
th2.start();
} catch (InterruptedException e) {
e.printStackTrace();
} }
}
begin
a线程永远suspend
thread2线程启动了，但是不能进入println方法，因为线程已经被a锁定且暂停
下面是另一种独占锁
package com.cky.thread; /**
* Created by edison on 2017/12/3.
*/
public class MyThread extends Thread{
private long i=0; @Override
public void run() {
while(true) {
i++;
}
}
}
package com.cky.test; import com.cky.thread.MyThread; /**
* Created by edison on 2017/12/3.
*/
public class Test2 {
public static void main(String[] args) {
try {
MyThread th = new MyThread();
th.start();
Thread.sleep(1000);
th.suspend();
System.out.println("main end");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
C:\itsoft\jdk\bin\java -Didea.launcher.port=7535 "-Didea.launcher.bin.path=C:\itsoft\idea\IntelliJ IDEA 2016.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\itsoft\jdk\jre\lib\charsets.jar;C:\itsoft\jdk\jre\lib\deploy.jar;C:\itsoft\jdk\jre\lib\ext\access-bridge-32.jar;C:\itsoft\jdk\jre\lib\ext\cldrdata.jar;C:\itsoft\jdk\jre\lib\ext\dnsns.jar;C:\itsoft\jdk\jre\lib\ext\jaccess.jar;C:\itsoft\jdk\jre\lib\ext\jfxrt.jar;C:\itsoft\jdk\jre\lib\ext\localedata.jar;C:\itsoft\jdk\jre\lib\ext\nashorn.jar;C:\itsoft\jdk\jre\lib\ext\sunec.jar;C:\itsoft\jdk\jre\lib\ext\sunjce_provider.jar;C:\itsoft\jdk\jre\lib\ext\sunmscapi.jar;C:\itsoft\jdk\jre\lib\ext\sunpkcs11.jar;C:\itsoft\jdk\jre\lib\ext\zipfs.jar;C:\itsoft\jdk\jre\lib\javaws.jar;C:\itsoft\jdk\jre\lib\jce.jar;C:\itsoft\jdk\jre\lib\jfr.jar;C:\itsoft\jdk\jre\lib\jfxswt.jar;C:\itsoft\jdk\jre\lib\jsse.jar;C:\itsoft\jdk\jre\lib\management-agent.jar;C:\itsoft\jdk\jre\lib\plugin.jar;C:\itsoft\jdk\jre\lib\resources.jar;C:\itsoft\jdk\jre\lib\rt.jar;C:\多线程核心技术\第一章\out\production\第一章;C:\itsoft\idea\IntelliJ IDEA 2016.3.3\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain com.cky.test.Test2
main end Process finished with exit code 1
如果改成如下
package com.cky.thread; /**
* Created by edison on 2017/12/3.
*/
public class MyThread2 extends Thread{
private long i=0; @Override
public void run() {
while(true) {
i++;
System.out.println("i="+i);
}
}
}
i=82093
i=82094
i=82095
i=82096
i=82097
i=82098
i=82099
i=82100
i=82101
控制台将不打印main end,
因为当程序运行到println方法内部时，同步锁没有被释放