用一個小例子來說明吧
static class ThreadA extends Thread { @Override public void run() { // TODO Auto-generated method stub super.run(); for (int i = 0; i < 10; i++) { System.out.println("ThreadA" + i); } } } static class ThreadB extends Thread { ThreadA a; public ThreadB(ThreadA a) { // TODO Auto-generated constructor stub this.a = a; } @Override public void run() { // TODO Auto-generated method stub super.run(); System.out.println("ThreadB start"); try { a.join(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println("ThreadB end"); } } public static void main(String[] args) { ThreadA a = new ThreadA(); ThreadB b = new ThreadB(a); b.start(); a.start(); }執(zhí)行結(jié)果:
ThreadB startThreadA0ThreadA1ThreadA2ThreadA3ThreadA4ThreadA5ThreadA6ThreadA7ThreadA8ThreadA9ThreadB end
首先b線程執(zhí)行,a線程join后,直接執(zhí)行完a,然后才執(zhí)行b,證實(shí)上述說法。 2、A.yield,A讓出位置,給B執(zhí)行,B執(zhí)行結(jié)束A再執(zhí)行。跟join意思正好相反!
static class ThreadA extends Thread { @Override public void run() { // TODO Auto-generated method stub super.run(); for (int i = 0; i < 10; i++) { System.out.println("ThreadA " + i); } } } static class ThreadB extends Thread { ThreadA a; public ThreadB(ThreadA a) { // TODO Auto-generated constructor stub this.a = a; } @Override public void run() { // TODO Auto-generated method stub super.run(); System.out.println("ThreadB start"); try { for (int i = 0; i < 10; i++) { if(i==2){ a.yield(); } System.out.println("ThreadB " + i); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println("ThreadB end"); } } public static void main(String[] args) { ThreadA a = new ThreadA(); ThreadB b = new ThreadB(a); b.start(); a.start(); }執(zhí)行結(jié)果:
ThreadB startThreadA 0ThreadB 0ThreadA 1ThreadB 1ThreadA 2ThreadB 2ThreadB 3ThreadB 4ThreadB 5ThreadB 6ThreadB 7ThreadB 8ThreadB 9ThreadB endThreadA 3ThreadA 4ThreadA 5ThreadA 6ThreadA 7ThreadA 8ThreadA 9
首先B執(zhí)行,然后A執(zhí)行;在B的循環(huán)中,i=2時,A執(zhí)行yield;接著B執(zhí)行完,才輪到A執(zhí)行。