函数式接口 Lambda表达式
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函数式接口定义
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任何接口,如果只包含唯一一个抽象方法,那么它就是函数式接口
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public interface Runnable{ public abstract void run(); }
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对于函数式接口,可以通过 Lambda 表达式来创建该接口的对象
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package com.fjbc.test; import java.util.ArrayList; import java.util.List; public class Test { public static void main(String[] args) { ILike like = null; like = () -> { System.out.println("i like lambda5"); }; like.like(); } } //1.定义一个函数式接口 interface ILike{ void like(); }
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线程状态
线程休眠_sleep
package com.fjbc.test;
public class Test倒计时{
public static void main(String[] args){
try {
tenDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public static void tenDown() throws InterruptedException {
int num = 10;
while(true){
Thread.sleep(1000);
System.out.println(num--);
if(num <= 0){
break;
}
}
}
}
线程礼让—yield(让CPU重新调用,礼让不一定成功!看CPU心情)
线程强制执行—join
观测线程状态
package com.fjbc.多线程;
/**
* 观察测试线程状态
*/
public class Demo21_ThreadState {
public static void main(String[] args) throws InterruptedException {
Thread thread = new Thread(() -> {
for (int i = 0; i < 5; i++) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("//");
});
//观察状态
Thread.State state = thread.getState();
System.out.println(state);
//观察启动后
thread.start();
state = thread.getState();
System.out.println(state);//Run
while (state != Thread.State.TERMINATED) {//只要现成不终止,就一直输出状态
Thread.sleep(100);
state = thread.getState();//更新线程状态
System.out.println(state);
}
//死亡后的线程不能再启动了,启动会报异常
//thread.start();
}
}
线程的优先级
- 优先级低只是意味着获得调度的概率低,并不是优先级低就不会被调用了,还是得看CPU心情
/**
* 线程优先级
*/
public class Demo22_ThreadPriority{
public static void main(String[] args) {
//主线程默认优先级
System.out.println(Thread.currentThread().getName()+"-->"+Thread.currentThread().getPriority());
MyPriority myPriority = new MyPriority();
Thread thread1 = new Thread(myPriority);
Thread thread2 = new Thread(myPriority);
Thread thread3 = new Thread(myPriority);
Thread thread4 = new Thread(myPriority);
Thread thread5 = new Thread(myPriority);
//先设置优先级,再启动
thread1.start();
thread2.setPriority(1);
thread2.start();
thread3.setPriority(4);
thread3.start();
thread4.setPriority(Thread.MAX_PRIORITY);//MAX_PRIORITY=10
thread4.start();
thread5.setPriority(8);
thread5.start();
}
}
class MyPriority implements Runnable{
@Override
public void run() {
System.out.println(Thread.currentThread().getName()+"-->"+Thread.currentThread().getPriority());
}
}
守护线程(daemon)
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线程分为用户线程和守护线程
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虚拟机必须确保用户线程执行完毕
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虚拟机不用等待守护线程执行完毕
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如,后台记录操作日志,监控内存,垃圾回收等待
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package com.fjbc.多线程; /** * 测试守护线程 * 上帝守护你 */ public class Demo23_DaemonThread { public static void main(String[] args) { God god = new God(); You you = new You(); Thread thread = new Thread(god); //默认false表示是用户线程,正常的线程都是用户线程... thread.setDaemon(true); //上帝守护线程启动 thread.start(); //你 用户线程启动 new Thread(you).start(); } } //上帝 class God implements Runnable{ @Override public void run() { while (true){ System.out.println("上帝保佑着你"); } } } //你 class You implements Runnable{ @Override public void run() { for (int i = 0; i < 36500; i++) { System.out.println("你一生都开心的活着"); } System.out.println("====goodbye!world===="); } }
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