Introduction to the understanding and use of multi-threading

1. Word part:

①process ②current current ③thread thread ④runnable available

⑤interrupt ⑥join join ⑦yield generated ⑧synchronize occurs simultaneously

2. Preview part

1. The difference between threads and processes:

The process is the basic unit of the system running program

The thread is the smallest unit for performing operations in the process

2 .Explain what are the two ways to create a thread

①Inherit the thread class

②Implement the Runnable interface

3. The life cycle of a thread can be divided into several stages, each What are the stages?

Five stages: ① Create ② Ready ③ Run ④ Block ⑤ Death

4. What method of thread can be used to set the sleep of the thread, the forced execution of the thread, and the courtesy of the thread?

They are: sleep(),join(),yield()

5. Under what circumstances is it necessary to synchronize threads? There are several ways to synchronize threads

When access conflicts occur,

need to be done in two ways: ① Synchronization method ② Synchronization code block

3. Practice part

1. Create a thread using a method that inherits the Thread class, Display the corresponding content

First create a thread class:

package oneOne;

public class MyRunnableone extends Thread{

public void run() {
for(int i=1;i<=20;i++){
System.out.println(i+".Hello, from thread"+Thread.currentThread().getName());

}
}
}

Create the main method class again and remove it

package oneOne;

public class testone {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
MyRunnableone my=new MyRunnableone();
MyRunnableone my1 =new MyRunnableone();
my.start();
my1.start();
}

}

2. Create a thread by implementing the Runnable interface

Same as the first one, create the implementation class first:

package oneTwo;

public class MyRunnabletwo implements Runnable{

public void run() {
for(int i=1;i<=20;i++){
System.out.println(i+".Hello, from thread"+Thread.currentThread().getName());

}
}

}

Remain method:

package oneTwo;

public class testtwo {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
MyRunnabletwo my=new MyRunnabletwo();
MyRunnabletwo my1=new MyRunnabletwo();
Thread tr=new Thread(my);
Thread tr1=new Thread(my1);
tr.start();
tr1.start();
}

}

3. Use multi-threading to simulate multi-person hiking

First create an inheritance or implementation class (I used inheritance here):

package oneThree;

public class MyRunnablethree extends Thread{
private int time;
public int num=0;
public MyRunnablethree(String name,int time,int kio) {
super(name);
this.time=time;
this.num=kio*1000/100;

}
public void run() {

while (num>0) {
try {
Thread.sleep(this.time);
} catch (InterruptedException e) {
// TODO: handle exception
e.printStackTrace ();
}
System.out.println(Thread.currentThread().getName()+"Climbed 100 meters! ");

num--;
}
System.out.println(Thread.currentThread().getName()+"End point reached!");
}

}

Remain method:

package oneThree;

public class testthree {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
MyRunnablethree young=new MyRunnablethree("Young man", 500, 1);
MyRunnablethree old=new MyRunnablethree( "Elderly", 1500, 1);
MyRunnablethree child=new MyRunnablethree("Child", 600, 1);
System.out.println("************Start climbing the mountain *********");
old.start();
young.start();
child.start();
}

}

4. Display and set thread priority

Inherit or implement the class first:

package oneFour;

public class MyRunnablefour extends Thread{
public void run() {
Thread.currentThread().setPriority(1);
System.out.println("Sub-thread name: "+Thread.currentThread().getName()+", priority : "+Thread.currentThread().getPriority());
}
}

Then main:

package oneFour;

public class testfour {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
MyRunnablefour myf=new MyRunnablefour();
myf.start();
System.out.println("****************Display the default priority********");
System.out .println("Main thread name: "+Thread.currentThread().getName()+", priority: "+Thread.currentThread().getPriority());
Thread.currentThread().setPriority(10 );
System.out.println("********************************** after modifying the default priority");
//myf.setPriority (1);
System.out.println("Main thread name: "+Thread.currentThread().getName()+", priority: "+Thread.currentThread().getPriority());
//System.out.println("Sub-thread name: "+MyRunnablefour.currentThread().getName()+", priority: "+MyRunnablefour.currentThread().getPriority());


}

}

5. Simulate calling a number and seeing a doctor

First inherit or implement the class:

package oneFive;

public class MyRunnablefive extends Thread{
private int time;
//public int pertail=0;
public MyRunnablefive(String common,int time) {
super(common);
this. time=time;

}
public void run() {
Thread.currentThread().setPriority(8);
for(int i=1;i<=10;i++ ){
try {
Thread.sleep(this.time);
} catch (InterruptedException e) {
// TODO: handle exception
e.printStackTrace();
}
System.out.println("Special number: "+i+" patient is seeing a doctor! ");

}
}

}

Remain:

package oneFive;

public class testfive {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
//MyRunnablefive pertail=new MyRunnablefive(" Special number", 1000);

Thread temp=new Thread(new MyRunnablefive("Special number", 400));
temp.start();
Thread.currentThread().setPriority (4);
for(int i=1;i<=50;i++){

if(i==11){

try {
temp.join ();
} catch (InterruptedException e) {
// TODO: handle exception
e.printStackTrace();
}
}
try {
Thread.sleep (200);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("Normal number :"+i+"patient is being treated");

}

}
}

6. Multi-threaded simulation relay race

First Create an inheritance or implementation class:

package oneSix;

public class runSix implements Runnable{
private int meters=1000;
public runSix(){


}
@Override
public void run() {
// TODO Auto-generated method stub
//System.out.println("Coming in");
while (true) {
//type type = (type) true.nextElement();
synchronized (this) {
if(meters<=100){
break;

}
System.out.println(Thread.currentThread().getName()+" Got the baton! ");
for (int i = 0; i < 100; i+=10) {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+"ran"+(i+10 )+"meters!");
}
meters-=100;
}
}
}

}

Then main interface class:

package oneSix;

public class testsix {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
runSix ru=new runSix();
for (int i = 0; i < 5; i++) {
new Thread(ru,(i+1) +"Player No.").start();
}
}

}

7. Multi-threaded simulated network ticket purchase

Taopaopao, Zhang votes, scalpers, grab ten votes together, limit scalpers to only grab one ticket

First create an inheritance or implementation class:

package oneSeven;

public class siteSeven implements Runnable{
private int count=10;
private int num=0;
private boolean flag=false;

@Override
public void run () {
// TODO Auto-generated method stub
//System.out.println("Coming in");
while (!flag) {

synchronized (this) {
//System.out.println("Coming in");
if(count<=0){
flag=true;
return;
}
num++;
count--;
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace( );
}
String name=Thread.currentThread().getName();
if(name.equals("scalper")){
System.out.println(name+"rob The "+num+"th ticket is reached, and "+count+" tickets remain! ");
break;
}
System.out.println(name+"Grab the "+num+"th ticket, "+count+" tickets remaining! ");
}
}
}

}

Create the main interface class again:

package oneSeven;

public class testseven {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto- generated method stub
siteSeven si=new siteSeven();
Thread per1=new Thread(si,"Dadong");
Thread yellow=new Thread(si,"Scalper");
Thread per2=new Thread(si,"Qizhen");
per1.start();
yellow.start();
per2.start();
}

}

Four: Summary:

1. The methods in the Thread class implement operations on thread objects

①Adjust the priority of the thread

② Thread sleep sleep()

③ Thread forced operation join()

④Thread courtesy yield()

2. Multi-threading allows programmers to write programs that maximize the use of the CPU Efficient program

3. Two ways to create a thread:

①Declare a subclass that inherits the Thread class and implement the run() method of the Thread class

②Declaration A class that implements the Runnable interface, and then implements the run() method

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