class?NewThread?extends?Thread?{
????NewThread()?{
????????//?Create?a?new,?second?thread
???? super("Demo?Thread");
????????System.out.println("Child?thread:?"?+?this);
????????start();?//?Start?the?thread
????}
????//?This?is?the?entry?point?for?the?second?thread.
????public?void?run()?{
????????try?{
????????????for(int?i?=?5;?i?>?0;?i--)?{
????????????????System.out.println("Child?Thread:?"?+?i);
????????????????Thread.sleep(500);
????????????}
????????}?catch?(InterruptedException?e)?{
????????????System.out.println("Child?interrupted.");
????????}
????????System.out.println("Exiting?child?thread.");
????}
}
class?helloworld?{
????public?static?void?main(String?args[])?{
????????new?NewThread();?//?create?a?new?thread
????????try?{
????????????for(int?i?=?5;?i?>?0;?i--)?{
????????????????System.out.println("Main?Thread:?"?+?i);
????????????????Thread.sleep(1000);
???????????}
????????}?catch?(InterruptedException?e)?{
????????????System.out.println("Main?thread?interrupted.");
????????}
????????System.out.println("Main?thread?exiting.");
????}
}這里我一直不明白?第三行?super("Demo Thread");這一句創建的是父類，為什么下面打印this就成了父類了，這里也沒有轉型和賦值什么的操作啊，為什么this就成了父類了
java中super和this的用法
慕粉1600176492
2018-02-23 15:01:51