Java多线程-run方法与start方法的区别

package com.interview;
/**
 * java多线程的两种实现方式以及run、start方法的区别
 * @author MEI.LIU
 *
 */
public class ThreadTest {
    public static void main(String[] args) throws InterruptedException {
        ThreadTest tt = new ThreadTest();
        Thread1 t1 = tt.new Thread1();
        Thread2 t2 = tt.new Thread2();
        Thread3 t3 = tt.new Thread3();
        Thread4 t4 = tt.new Thread4();
        //实现Runnable方法的方式必须要用new Thread(tt.new Thread5())来转换为Thread类型，才能调用Thread的start方法)
        Thread t5 = new Thread(tt.new Thread5());
        t1.start();
        Thread.sleep(1000);
        t2.start();
        Thread.sleep(1000);
        t3.start();
        Thread.sleep(1000);
        t4.start();
        Thread.sleep(10000);
        ((Thread) t5).start();
    }

    class Thread1 extends Thread {
        public void run() {
            try {
                while (true) {
                    for (int i = 1000;; i--) {
                        Thread.sleep(1000);
                        System.out.println("现在i的值为：" + i);
                    }
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    class Thread2 extends Thread {
        public void run() {
            try {
                while (true) {
                    System.out.println("哈哈哈哈哈哈哈哈哈");
                    Thread.sleep(666);
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    class Thread3 extends Thread {
        public void run() {
            try {
                while (true) {
                    for (int j = 1000;; j--) {
                        System.out.println("目前，j的值是：" + j);
                        Thread.sleep(2000);
                    }
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    class Thread4 extends Thread {
        public void run() {
            try {
                while (true) {
                    System.out.println("TTTTTTTTTTTTTTTTTTT");
                    Thread.sleep(5000);
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    class Thread5 implements Runnable {
        public void run() {
            try {
                while (true) {
                    System.out.println("咚咚咚咚咚咚咚咚咚咚咚咚咚");
                    Thread.sleep(1400);
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

package com.interview;
/**
 * java多线程的两种实现方式以及run、start方法的区别
 * @author MEI.LIU
 *
 */
public class ThreadTest {
	public static void main(String[] args) throws InterruptedException {
		ThreadTest tt = new ThreadTest();
		Thread1 t1 = tt.new Thread1();
		Thread2 t2 = tt.new Thread2();
		Thread3 t3 = tt.new Thread3();
		Thread4 t4 = tt.new Thread4();
		//实现Runnable方法的方式必须要用new Thread(tt.new Thread5())来转换为Thread类型，才能调用Thread的start方法)
		Thread t5 = new Thread(tt.new Thread5());
		t1.start();
		Thread.sleep(1000);
		t2.start();
		Thread.sleep(1000);
		t3.start();
		Thread.sleep(1000);
		t4.start();
		Thread.sleep(10000);
		((Thread) t5).start();
	}

	class Thread1 extends Thread {
		public void run() {
			try {
				while (true) {
					for (int i = 1000;; i--) {
						Thread.sleep(1000);
						System.out.println("现在i的值为：" + i);
					}
				}
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}

	class Thread2 extends Thread {
		public void run() {
			try {
				while (true) {
					System.out.println("哈哈哈哈哈哈哈哈哈");
					Thread.sleep(666);
				}
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}

	class Thread3 extends Thread {
		public void run() {
			try {
				while (true) {
					for (int j = 1000;; j--) {
						System.out.println("目前，j的值是：" + j);
						Thread.sleep(2000);
					}
				}
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}

	class Thread4 extends Thread {
		public void run() {
			try {
				while (true) {
					System.out.println("TTTTTTTTTTTTTTTTTTT");
					Thread.sleep(5000);
				}
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}

	class Thread5 implements Runnable {
		public void run() {
			try {
				while (true) {
					System.out.println("咚咚咚咚咚咚咚咚咚咚咚咚咚");
					Thread.sleep(1400);
				}
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
}

区别：调用start方法实现多线程，而调用run方法没有实现多线程

    Start:

    用start方法来启动线程，真正实现了多线程运行，这时无需等待run方法体代码执行完毕而直接继续执行下面的代码。通过调用Thread类的start（）方法来启动一个线程，这时此线程处于就绪（可运行）状态，并没有运行，一旦得到spu时间片，就开始执行run（）方法，这里方法run（）称为线程体，它包含了要执行的这个线程的内容，Run方法运行结束，此线程随即终止。

    Run:

    run（）方法只是类的一个普通方法而已，如果直接调用Run方法，程序中依然只有主线程这一个线程，其程序执行路径还是只有一条，还是要顺序执行，还是要等待run方法体执行完毕后才可继续执行下面的代码，这样就没有达到写线程的目的。

    总结：调用start方法方可启动线程，而run方法只是thread的一个普通方法调用，还是在主线程里执行。

 控制台输出结果：