Java基础：多线程

进程和线程：进程可以理解为是正在执行的程序。线程是最小的分派代码单元，程序可以一次执行多项任务。

线程的状态：running(运行)，read to run(准备就绪)，suspended(挂起)，resumed(继续执行)，blocked(阻塞状态),terminated(终止)。

示例代码：

class MyThread implements Runnable{ //实现Runnable接口
String thrdName;
MyThread(String name){ //构造
thrdName=name;
}
public void run(){ //线程开始执行
System.out.println(thrdName+" starting.");
try{
for(int i=0;i<10;i++){
Thread.sleep(400); //线程休眠时间（毫秒）
System.out.println("In "+thrdName+"i is "+i);
}
}catch(InterruptedException e){
System.out.println(e);
}
System.out.println(thrdName+" termination.");
}
}
class UseThreads{
public static void main(String[] args){
System.out.println("Main thread starting.");
MyThread mt=new MyThread("Child #1"); //创建一个可运行的对象
Thread newThread=new Thread(mt); //构造一个线程
newThread.start(); //开始运行线程
for(int i=0;i<50;i++){
try{
Thread.sleep(100); //休眠时间
}catch(InterruptedException e){ //捕获异常
System.out.println(e);
}
}
System.out.println("Main thread ending");
System.out.println("Child #1×Ô¼ºÔËÐÐ");
mt.run(); //直接调用run()方法
}
}
------------------------------------------------------------------------------------------------------
创建多线程：
class MyThreadsss implements Runnable{ //实现Runnable接口
Thread thrd; //Thread对象
MyThreadsss(String name){ //构造
thrd=new Thread(this,name); //创建时运行
thrd.start();
}
public void run() { //run()方法
System.out.println(thrd.getName()+" starting.");
try {
for(int i=0;i<10;i++) {
Thread.sleep(400); //线程休眠
System.out.println("In "+thrd.getName()+"i is "+i);
}
}catch(InterruptedException e) {
System.out.println(e);
}
System.out.println(thrd.getName()+" terminating.");
}
}
public class MoreThreads {
public MoreThreads() {
}
public static void main(String[] args) {
System.out.println("Main thread starting.");
MyThreadsss mt1=new MyThreadsss("Child#1"); //多个子线程
MyThreadsss mt2=new MyThreadsss("Child#2");
MyThreadsss mt3=new MyThreadsss("Child#3");
do {
try {
Thread.sleep(100); //线程休眠
} catch (InterruptedException e) {
e.printStackTrace();
System.out.println("Main thread interrupted.");
}
}while(mt1.thrd.isAlive()||mt2.thrd.isAlive()||mt3.thrd.isAlive()); //isAlive()确定线程是否结束，运行返回true,结束返回false
mt1.thrd.join();//等待，直到指定线程结束
mt1.thrd.setPriority(Thread.NORM_PRIORITY+2); //设置线程优先级
mt2.thrd.setPriority(Thread.NORM_PRIORITY-2);
System.out.println("Main thread ending.");
}
}
------------------------------------------------------------------------------------------------
线程通信：notify() wait()之间的通信
class TickTock{
String state;
synchronized void tick(boolean running) { //synchronized修饰方法，方法同步
if(!running) {
state="ticked";
notify(); //通知其他等待的线程
return;
}
System.out.println("Ticked ");
try {
Thread.sleep(500);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
state="ticked";
notify(); //通知其他等待的线程
try {
while(!state.equals("tocked")) {
wait(); //等待
}
}catch(InterruptedException e) {
e.printStackTrace();
}
}
synchronized void tock(boolean running) { //同步方法
if(!running) {
state="tocked";
notify(); //通知其他等待的线程
return;
}
System.out.println("Tocked");
try {
Thread.sleep(500); //休眠
} catch (InterruptedException e1) {
e1.printStackTrace();
}
state="tocked";
notify(); //通知其他等待的线程
try {
while(!state.equals("ticked")) {
wait(); //等待
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
class MyThreadtc implements Runnable{ //实现Runnable接口
Thread thrd;
TickTock ttOb;
MyThreadtc(String name,TickTock tt){
thrd=new Thread(this,name); //创建对象时运行
ttOb=tt;
thrd.start();
}
public void run() { //run()方法
if(thrd.getName().compareTo("Tick")==0) {
for(int i=0;i<5;i++) {
ttOb.tick(true);
}
ttOb.tick(false);
}else {
for(int i=0;i<5;i++) {
ttOb.tock(true);
}
ttOb.tock(false);
}
}
}
public class ThreadCom {
public ThreadCom() {
}
public static void main(String[] args) {
TickTock tt=new TickTock();
MyThreadtc mt1=new MyThreadtc("Tick",tt);
MyThreadtc mt2=new MyThreadtc("Tock",tt);
try {
mt1.thrd.join(); //等待，知道线程结束
mt2.thrd.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
--------------------------------------------------------------------------------------
线程的挂起，继续执行和停止：
class MyThreadsrs implements Runnable{
Thread thrd;
boolean suspended; //为true时，线程挂起
boolean stopped; //为true时，线程终止
MyThreadsrs(String name){
thrd=new Thread(this,name);
suspended=false;
stopped=false;
thrd.start();
}
public void run() {
System.out.println(thrd.getName()+" starting.");
try {
for(int i=1;i<1000;i++) {
System.out.print(i+" ");
if((i%10)==0) {
System.out.println();
Thread.sleep(250);
}
synchronized(this) { //同步代码块检查suspended和stopped
while(suspended) {
wait();
}
if(stopped) break;
}
}
}catch(InterruptedException e) {
e.printStackTrace();
}
System.out.println(thrd.getName()+" ending");
}
synchronized void mystop() { //stop()方法
stopped=true;
suspended=false;
notify();
}
synchronized void mysuspend() { //suspend()方法
suspended=true;
}
synchronized void myresume() { //resume()方法
suspended=false;
notify();
}
}
public class Suspend {
public Suspend() {
}
public static void main(String[] args) {
MyThreadsrs ob1=new MyThreadsrs("My Thread");
try {
Thread.sleep(1000);
ob1.mysuspend();
System.out.println("Suspending thread.");
Thread.sleep(1000);
ob1.myresume();
System.out.println("Resuming thread.");
Thread.sleep(1000);
ob1.mysuspend();
System.out.println("Suspending thread.");
Thread.sleep(1000);
ob1.myresume();
System.out.println("Resuming thread.");
Thread.sleep(1000);
ob1.mysuspend();
System.out.println("Stopping thread.");
ob1.mystop();
} catch (InterruptedException e) {
e.printStackTrace();
}
try {
ob1.thrd.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
--------------------------------------------------------------------------------------
主线程：
public class UseMain {
public UseMain() {
}
public static void main(String[] args) {
Thread thrd;
thrd=Thread.currentThread(); //主线程
System.out.println("Main thread is called:"+ thrd.getName()); //获取线程名
System.out.println("Priority:"+thrd.getPriority()); //获取线程优先级别
System.out.println();
System.out.println("Setting name and priority.");
thrd.setName("Thread #1"); //设置主线程名字
thrd.setPriority(Thread.NORM_PRIORITY+3); //设置主线程优先级
System.out.println("Main thread is called:"+ thrd.getName());
System.out.println("Priority:"+thrd.getPriority());
System.out.println();
}
}

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