public synchronized void start() {
        /**
         * This method is not invoked for the main method thread or "system"
         * group threads created/set up by the VM. Any new functionality added
         * to this method in the future may have to also be added to the VM.
         *
         * A zero status value corresponds to state "NEW".
         */
        if (threadStatus != 0)
            throw new IllegalThreadStateException();

        /* Notify the group that this thread is about to be started
         * so that it can be added to the group's list of threads
         * and the group's unstarted count can be decremented. */
        group.add(this);

        boolean started = false;
        try {
            start0();
            started = true;
        } finally {
            try {
                if (!started) {
                    group.threadStartFailed(this);
                }
            } catch (Throwable ignore) {
                /* do nothing. If start0 threw a Throwable then
                  it will be passed up the call stack */
            }
        }
    }
//本地方法，调用C++
    private native void start0();

package com.joker_yue;

public class Test0 {
    public static void main(String[] args) {
        //获取CPU的核心数
        //CPU密集型，IO密集型
        System.out.println(Runtime.getRuntime().availableProcessors());

    }
}

/**
 * A thread state.  A thread can be in one of the following states:
 * <ul>
 * <li>{@link #NEW}<br>
 *     A thread that has not yet started is in this state.
 *     </li>
 * <li>{@link #RUNNABLE}<br>
 *     A thread executing in the Java virtual machine is in this state.
 *     </li>
 * <li>{@link #BLOCKED}<br>
 *     A thread that is blocked waiting for a monitor lock
 *     is in this state.
 *     </li>
 * <li>{@link #WAITING}<br>
 *     A thread that is waiting indefinitely for another thread to
 *     perform a particular action is in this state.
 *     </li>
 * <li>{@link #TIMED_WAITING}<br>
 *     A thread that is waiting for another thread to perform an action
 *     for up to a specified waiting time is in this state.
 *     </li>
 * <li>{@link #TERMINATED}<br>
 *     A thread that has exited is in this state.
 *     </li>
 * </ul>
 *
 * <p>
 * A thread can be in only one state at a given point in time.
 * These states are virtual machine states which do not reflect
 * any operating system thread states.
 *
 * @since   1.5
 * @see #getState
 */
public enum State {
    /**
     * Thread state for a thread which has not yet started.
     */
    NEW,

    /**
     * Thread state for a runnable thread.  A thread in the runnable
     * state is executing in the Java virtual machine but it may
     * be waiting for other resources from the operating system
     * such as processor.
     */
    RUNNABLE,

    /**
     * Thread state for a thread blocked waiting for a monitor lock.
     * A thread in the blocked state is waiting for a monitor lock
     * to enter a synchronized block/method or
     * reenter a synchronized block/method after calling
     * {@link Object#wait() Object.wait}.
     */
    BLOCKED,

    /**
     * Thread state for a waiting thread.
     * A thread is in the waiting state due to calling one of the
     * following methods:
     * <ul>
     *   <li>{@link Object#wait() Object.wait} with no timeout</li>
     *   <li>{@link #join() Thread.join} with no timeout</li>
     *   <li>{@link LockSupport#park() LockSupport.park}</li>
     * </ul>
     *
     * <p>A thread in the waiting state is waiting for another thread to
     * perform a particular action.
     *
     * For example, a thread that has called {@code Object.wait()}
     * on an object is waiting for another thread to call
     * {@code Object.notify()} or {@code Object.notifyAll()} on
     * that object. A thread that has called {@code Thread.join()}
     * is waiting for a specified thread to terminate.
     */
    WAITING,

    /**
     * Thread state for a waiting thread with a specified waiting time.
     * A thread is in the timed waiting state due to calling one of
     * the following methods with a specified positive waiting time:
     * <ul>
     *   <li>{@link #sleep Thread.sleep}</li>
     *   <li>{@link Object#wait(long) Object.wait} with timeout</li>
     *   <li>{@link #join(long) Thread.join} with timeout</li>
     *   <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
     *   <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
     * </ul>
     */
    TIMED_WAITING,

    /**
     * Thread state for a terminated thread.
     * The thread has completed execution.
     */
    TERMINATED;
}

package com.joker_yue;

//基本的卖票例子

/*
 * 真正的多线程开发，公司中的开发
 * 线程  就是一个单独的资源类，没有任何附属的操作
 * */
public class Test01 {
    public static void main(String[] args) {
        //并发：多个线程操作同一个资源类，把资源丢入线程
        Ticket ticket = new Ticket();

        new Thread(() -> {
            for (int i = 0; i < 60; i++) {
                ticket.sale();
            }
        }, "A").start();

        new Thread(() -> {
            for (int i = 0; i < 60; i++) {
                ticket.sale();
            }
        }, "B").start();

        new Thread(() -> {
            for (int i = 0; i < 60; i++) {
                ticket.sale();
            }
        }, "C").start();
    }
}

//资源类
class  Ticket {
    //属性+方法
    private int number = 40;

    //卖票的方式
    public synchronized void sale() {
        if (number > 0) {
            System.out.println(Thread.currentThread().getName() + "卖出了第" + (number--) + "张票" + "，剩余" + number);
        }
    }
}

Lock lock = new ReentrantLock();

package com.joker_yue;

//基本的卖票例子

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/*
 * 真正的多线程开发，公司中的开发
 * 线程  就是一个单独的资源类，没有任何附属的操作
 * */
public class Test02 {
    public static void main(String[] args) {
        //并发：多个线程操作同一个资源类，把资源丢入线程
        Ticket ticket = new Ticket();

        //@FunctionInterface 函数式接口
        new Thread(() -> {for (int i = 0; i < 40; i++)ticket.sale();}, "A").start();
        new Thread(() -> {for (int i = 0; i < 40; i++)ticket.sale();}, "B").start();
        new Thread(() -> {for (int i = 0; i < 40; i++)ticket.sale();}, "C").start();

}}

//Lock三部曲
//1，new ReentrantLock();        创建锁
//2，lock.lock();                加锁
//3，finally=>lock.unlock();     解锁

class Ticket2 {
    //属性+方法
    private int number = 30;

    Lock lock = new ReentrantLock();

    //卖票的方式
    public synchronized void sale() {
        lock.lock();//加锁
        try {
            //业务代码
            if (number > 0) {
                System.out.println(Thread.currentThread().getName() + "卖出了第" + (number--) + "张票" + "，剩余" + number);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();//解锁
        }
    }

}

package com.joker_yue.pc;

/*线程之间的通信问题
 * 线程交替执行 A B 操作同一个变量 要使最终num=0
 * A num+1
 * B num-1
 * 通知 等待唤醒
 *  */

public class A {
    public static void main(String[] args) {
        Data data = new Data();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }
        }, "A").start();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }
        }, "B").start();
    }
}


//判断等待，业务，通知
class Data {//数字类
    private int number = 0;

    //+1
    public synchronized void increment() throws InterruptedException {
        while (number != 0) {//while自旋锁
            //等待
            this.wait();
        }
        number++;
        System.out.println(Thread.currentThread().getName() + "=>" + number);
        //通知其他线程+1已经完成
        this.notifyAll();
    }

    public synchronized void decrement() throws InterruptedException {
        while (number == 0) {//while自旋锁
            //等待
            this.wait();
        }
        number--;
        System.out.println(Thread.currentThread().getName() + "=>" + number);
        //通知其他线程-1已经完成
        this.notifyAll();
    }
}