Multithreading -- callable interface, lambda

Callable The benefits of
1, You can define the return value
2, You can throw an exception
Four steps to implement the interface
1, Create execution service ： ExecutorService ser= Executors.newFixedThreadPool(3);
2, Submit for execution ： Future result1=ser.submit(th1);
3, To get the results ： boolean rs1= result1.get();
4, Close the service ：ser.shutdownNow();

ackage CallableDemo;

import ThreadDemo.ThreadDemo01;
import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.concurrent.*;

public class Demo01 implements Callable<Boolean> {
    
    private String url;  // Address of network picture 
    private String name;// Saved file name 

    public Demo01(String url, String name) {
    
        this.url = url;
        this.name = name;
    }

    public static void main(String[] args) throws ExecutionException, InterruptedException {
    
        Demo01 th1=new Demo01("https://img2.baidu.com/it/u=1814268193,3619863984&fm=253&app=138&size=w931&n=0&f=JPEG&fmt=auto?sec=1658682000&t=d20c88a4eebf882f4f8950f8613ac1b4","n.jpg");
        Demo01 th2=new Demo01("https://img2.baidu.com/it/u=1814268193,3619863984&fm=253&app=138&size=w931&n=0&f=JPEG&fmt=auto?sec=1658682000&t=d20c88a4eebf882f4f8950f8613ac1b4","m.jpg");
        Demo01 th3=new Demo01("https://img2.baidu.com/it/u=1814268193,3619863984&fm=253&app=138&size=w931&n=0&f=JPEG&fmt=auto?sec=1658682000&t=d20c88a4eebf882f4f8950f8613ac1b4","p.jpg");
        // Create execution service 
        ExecutorService ser= Executors.newFixedThreadPool(3);
        // Submit for execution 
        Future<Boolean> result1=ser.submit(th1);
        Future<Boolean> result2=ser.submit(th2);
        Future<Boolean> result3=ser.submit(th3);
        // To get the results 
        boolean rs1= result1.get();
        boolean rs2= result2.get();
        boolean rs3= result3.get();

        System.out.println(rs1);
        // Close the service 
        ser.shutdown();
    }

    // Download the execution of the image thread 
    @Override
    public Boolean call() throws Exception {
    
       webDownLoader web=new webDownLoader();
        web.downloader(url,name);
        System.out.println(" Downloaded the file named "+name);
        return true;
    }

    // Downloader 
    class webDownLoader {
    
        // Download method 
        public void downloader(String url,String name){
    
            try {
    
                FileUtils.copyURLToFile(new URL(url),new File(name));
            } catch (IOException e) {
    
                e.printStackTrace();
                System.out.println("IO abnormal "+"downLoader Problems arise ");
            }
        }
    }
}

lambda expression

Why use lambda expression
Avoid too many anonymous inner class definitions
Make the code simpler

Any interface , Contains only one abstract method , So it's a functional interface
For functional interfaces, we can use lambda Expression creates the object of the interface

package LamdaStudy;

public class Demo01 {
    
    public static void main(String[] args) {
    
        ILike like = new Like();
        like.lambda();

        like=new Like2();
        like.lambda();


        //4, Local inner classes 
        class Like3 implements ILike{
    
            @Override
            public void lambda() {
    
                System.out.println("I Like Lambda3");
            }
        }
        like=new Like3();
        like.lambda();

        //5, Anonymous inner class , There is no class name , You have to use an interface or a parent class 
        like =new ILike() {
    
            @Override
            public void lambda() {
    
                System.out.println("I Like Lambda4");
            }
        };
        // Use anonymous inner class 
        like.lambda();

        //6, use lambda simplify 
        like=()->{
    
            System.out.println("I Like Lambda5");
        };
        like.lambda();
    }


//3, Static inner class 
    static class Like2 implements ILike{
    
    @Override
    public void lambda() {
    
        System.out.println("I Like Lambda2");
    }
}

}

// Interface 
interface ILike {
    
    void lambda();
}
    //2, Implementation class 
     class Like implements ILike{
    

        @Override
        public void lambda() {
    
            System.out.println("I Like Lambda");
        }
    }

lambda Expression simplification

// summary
//1, When there is a parameter , You can omit parentheses , Parameter types can also be omitted
//2, When there are multiple parameters , Parentheses cannot be omitted , But both parameter types must exist or not exist
//3, When the method body has only one sentence , You can omit the braces , However, multiple statements cannot be omitted

package LamdaStudy;

public class Demo02 {
    
    public static void main(String[] args) {
    
        ILove love=new Love();
        love.Love(12);

        // Anonymous inner class 
        love=new ILove() {
    
            @Override
            public void Love(int a) {
    
                System.out.println("I Love You"+a);
            }
        };
        love.Love(2);

        //1,lambda expression 
       ILove love1=(int a)->{
    
           System.out.println("I Love You"+a);
       };
       love1.Love(3);

       //2, simplify 1 Remove parameter type 
        love=(a)->{
    
            System.out.println("I Love You"+a);
        };
        love.Love(5);

        //3, Simplified brackets ()
        love = a->{
    
            System.out.println("I Love You"+a);
        };
        love.Love(6);

        //4, simplify 3 Get rid of {}
        love = a->System.out.println("I Love You"+a);
        love.Love(7);

}
interface ILove{
    
    void Love(int a);
}

class Love implements ILove{
    

    @Override
    public void Love(int a) {
    
        System.out.println("I Love You"+a);
    }
}