java 如何秒速写一个线程启动

Posted 2021-07-15 qianbo_insist

线程

java 的线程相对c，c++来说基本是类似的，尤其是使用lamba都是非常快速的就能启动一个线程，相对于使用api来说，简化了很多。有几种方式可以使用：

1、使用静态内部类

java的线程类可以直接从Runnable上继承，实现 run()函数即可

static Map<String,String> v_map = new ConcurrentHashMap<String,String>();

    static class th1 implements Runnable{
		public void run() {
            for(int i = 0; i < 10; i ++) {  
                v_map.put(String.valueOf(i), String.valueOf(i));  
            }  
             //遍历值  
            for (String value : v_map.values()) {
                System.out.println("thread1 value = " + value);
            }
 		}
	}

调用，直接new Thread ，调用方法start().

new Thread(new th1()).start();

2、直接new Thread

这种方式更为方便，不用写一个class，直接启动线程即可，如果没有其他需要交互的变量和方法，这种方式更为直接。

		new Thread(new Runnable(){
			public void run() {
                for (String value : v_map.values()) {
                    System.out.println("thread2 value = " + value);
                }
			}
		}).start();

3、lamba简化写法

new Thread(()->{
           for (String value : v_map.values()) {
            System.out.println("thread3 value = " + value);
          }
}).start();

()->的写法开始流行了，这样看起来和用起来更简单了是不是？
下面是所有代码，使用ConcurrentHashMap做实验，多个线程同时操作一个ConcurrentHashMap来演示：

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class threadclass {

    static Map<String,String> v_map = new ConcurrentHashMap<String,String>();

    static class th1 implements Runnable{


		public void run() {
            for(int i = 0; i < 10; i ++) {  
                v_map.put(String.valueOf(i), String.valueOf(i));  
            }  
             //遍历值  
            for (String value : v_map.values()) {
                System.out.println("thread1 value = " + value);
            }
 		}
	}
	public static void main(String[] args) {

		new Thread(new th1()).start();
		
		new Thread(new Runnable(){
			public void run() {
                for (String value : v_map.values()) {
                    System.out.println("thread2 value = " + value);
                }
			}
		}).start();
		
		//简化 lambda
		new Thread(()->{
           for (String value : v_map.values()) {
            System.out.println("thread3 value = " + value);
            }
		}).start();
	}
}

输出：
thread1 value = 0
thread1 value = 1
thread1 value = 2
thread1 value = 3
thread1 value = 4
thread2 value = 0
thread2 value = 1
thread1 value = 5
thread2 value = 2
thread2 value = 3
thread1 value = 6
thread2 value = 4
thread2 value = 5
thread1 value = 7
thread1 value = 8
thread2 value = 6
thread2 value = 7
thread1 value = 9
thread2 value = 8
thread2 value = 9
thread3 value = 0
thread3 value = 1
thread3 value = 2
thread3 value = 3
thread3 value = 4
thread3 value = 5
thread3 value = 6
thread3 value = 7
thread3 value = 8
thread3 value = 9