java 多线程循环输出ABC

第一：使用对象lock和unlock控制输出：

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReentrantLock;

public class ABC {
private static int state = 0;

public static void main(String[] args) {
final Lock l = new ReentrantLock();

Thread A = new Thread(new Runnable(){
@Override
public void run() {
while (state<=30) {
l.lock();
if(state%3==0){
System.out.println("A");
state ++;
}
l.unlock();
}
}
});
Thread B = new Thread(new Runnable(){
@Override
public void run() {
while (state<=30) {
l.lock();
if(state%3==1){
System.out.println("B");
state ++;
}
l.unlock();
}
}
});
Thread C = new Thread(new Runnable(){
@Override
public void run() {
while (state<=30) {
l.lock();
if(state%3==2){
System.out.println("C");
state ++;
}
l.unlock();
}
}
});
A.start();
B.start();
C.start();
}

}

第二：用synchronized对该资源对象上锁，用notify唤醒占用该资源的线程，用wait()挂起占用该资源的线程

public class TestThread {
public static void main(String[] args) {
String stra = "A";
String strb = "B";
String strc = "C";

TestABC t= new TestABC();

new Thread(){
public void run(){
t.outABC(stra, strb);
}
}.start();

try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

new Thread(){
public void run(){
t.outABC(strb, strc);
}
}.start();

new Thread(){
public void run(){
t.outABC(strc, stra);
}
}.start();
}
}

class TestABC{

public void outABC(String str1,String str2){
while(true){
synchronized (str1) {
System.out.println(str1);
synchronized (str2) {
str2.notify();
}
try{
str1.wait();
Thread.sleep(100);
}catch(Exception e){
System.out.println(e);
}
}
}
}
}

总结：最重要的是明白锁的是什么，不是线程，是资源对象。唤醒的挂起的锁死的都是一个共享资源上的线程，并不能对创建的线程对象进行操作。（迄今。个人理解）