OutPut:

 

Output:

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Descending order:

Ascending order:

•  Basically to display numbers from 1 to 10 or a series we will use for , while or do while loop
• So here is the programs to do same thing without using loop.
• This is possible in two ways
• First one is to display by printing all those things using system.out.println.
• second one is by using recursive method call lets see these two programs

Solution #1:

Output:

Solution #2

Java How To Convert Map Values To List In Java Some Different Ways Below are some common methods for doing so:

1. How to use values() with ArrayList

You can convert the values of a Map to a List in Java using various approaches. 

below are a few common methods:

1. Using ArrayList andvalues()

import java.util.*;

public class MapToListExample {
    public static void main(String[] args) {
        Map<Integer, String> map = new HashMap<>();
        map.put(1, "Apple");
        map.put(2, "Banana");
        map.put(3, "Cherry");

        // Convert values to List
        List<String> list = new ArrayList<>(map.values());

        System.out.println(list);  // Output: [Apple, Banana, Cherry]
    }
}

2. Using Java 8 Stream API

import java.util.*;
import java.util.stream.Collectors;

public class MapToListExample {
    public static void main(String[] args) {
        Map<Integer, String> map = Map.of(1, "Apple", 2, "Banana", 3, "Cherry");

        // Convert values to List using Stream
        List<String> list = map.values().stream().collect(Collectors.toList());

        System.out.println(list);  // Output: [Apple, Banana, Cherry]
    }
}

3. Using forEach Loop

import java.util.*;

public class MapToListExample {
    public static void main(String[] args) {
        Map<Integer, String> map = new HashMap<>();
        map.put(1, "Apple");
        map.put(2, "Banana");
        map.put(3, "Cherry");

        List<String> list = new ArrayList<>();
        map.values().forEach(list::add);

        System.out.println(list);  // Output: [Apple, Banana, Cherry]
    }
}

💡 Choose the method based on your Java version:

• Use ArrayList<>(map.values()) for simple cases.
• Use Stream API (map.values().stream().collect(Collectors.toList())) in Java 8+ for a functional approach.
• Use a forEach loop if modifying the list during iteration.

Removing duplicate elements form an array using collections:

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Map:

• Map is key-value pair.
• Map Interface represents a mapping between key and value.
• Map having:

Common   class
package com.instanceofjavaforus;

public class Common {

    int x;
   
    boolean flag=true;
    //if flag is true producer thread has to produce
    // if flag is false consumer thread has to produce

    synchronized public void produce(int i){
       
        if(flag){
           
            x=i;
            System.out.println("producer thread has produced "+i);
            flag=false;
            notify();
            try {
                wait();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }      
        }
     }
   

    synchronized public int consume(){
        if(flag){
            try {
                wait();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
           
        }
        flag=true;
        notify();
        return x;
    }
   
}

package com.instanceofjavaforus;

public class ProducerThread extends Thread {
    Common c;
   
    ProducerThread(Common c){
        this.c=c;
    }
   
    public void run(){
        int i=0;
        while(true){
           
            i++;
            c.produce(i);
           
           
            try {
                Thread.sleep(600);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } 
        } 
    } 
}

ConsumerThread:

package com.instanceofjavaforus;

public class ConsumerThread extends Thread {
   
    Common c;
   
    ConsumerThread(Common c){
        this.c=c;
    }
   
    public void run(){
       
        while(true){
           
            int x=c.consume();
            System.out.println("Consumer consumes"+x);
            try {
                Thread.sleep(600);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } 
        } 
    }
}

ProducerConsumerTest:

package com.instanceofjavaforus;

public class ProducerConsumerTest {
   
    public static void main(String args[]){
        Common c= new Common();
        ProducerThread pt=new ProducerThread(c);
        ConsumerThread ct= new ConsumerThread(c);
        pt.start();
        ct.start();
    }
}

Output:

producer thread has produced 1
Consumer consumed 1
producer thread has produced 2
Consumer consumed 2
producer thread has produced 3
Consumer consumed 3
producer thread has produced 4
Consumer consumed 4
producer thread has produced 5
Consumer consumed 5
producer thread has produced 6
Consumer consumed 6

Output:

 Output:

Output:

Output:

 

Output:

Output:

• Lets see an example program to get largest element in an integer array. and also find second largest element in the same array.

Output:

Output: