一、线程
二、线程的特点
三、线程的生命周期
四、Thread类
Thread类是java.lang包中的一个类，Thread类的对象用来代表线程，通过继承Thread类创建、启动并执行一个线程的步骤：①创建一个继承Thread类的子类；②覆写Thread类的run()方法；③创建线程类的一个对象；④通过线程类的对象调用start()方法启动线程(启动之后会自动调用覆写的run()方法执行线程)。
案例分析：
public class Demo5 {
public static void main(String[] args) {
ThreadA threadA = new ThreadA();
threadA.start();
ThreadB threadB = new ThreadB();
threadB.start();
}
}
class ThreadA extends Thread{
public void run(){
for(int i=0;i<100;i++){
System.out.println(i);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
class ThreadB extends Thread{
public void run(){
for(char i= 'a';i<'z';i++){
System.out.println(i);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
五、Runnable接口
六、线程的休眠
七、线程的加入
八、线程的中断
九、线程的安全
（一）案例之线程不安全，出现脏读
public class Demo6 implements Runnable{
int num = 10;
public static void main(String[] args) {
Demo6 demo = new Demo6();
Thread t1 = new Thread(demo,"线程一");
Thread t2 = new Thread(demo,"线程二");
Thread t3 = new Thread(demo,"线程三");
Thread t4 = new Thread(demo,"线程四");
t1.start();
t2.start();
t3.start();
t4.start();
}
@Override
public void run() {
while (true){
if(num>0){
System.out.println("票数："+num--);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
（二）线程同步机制synchronized关键字
两种方法：
案例剖析：
public class Demo6 implements Runnable{
int num = 10;
public static void main(String[] args) {
Demo6 demo = new Demo6();
Thread t1 = new Thread(demo,"线程一");
Thread t2 = new Thread(demo,"线程二");
Thread t3 = new Thread(demo,"线程三");
Thread t4 = new Thread(demo,"线程四");
t1.start();
t2.start();
t3.start();
t4.start();
}
@Override
public void run() {
while (true){
synchronized (this){
if(num>0){
System.out.println("票数："+num--);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
}
