Question

How to remove duplicate Strings from ArrayList in Java

Answer 1

package javaapplication1;

import java.util.ArrayList;

public class JavaApplication1 {

    static ArrayList<String> RemoveDuplicates(ArrayList<String> list) {

        ArrayList<String> result = new ArrayList<>();

        for (String s : list) {

            if (!result.contains(s)) {
                result.add(s);
            }
        }
        return result;
    }

    public static void main(String[] args) {

        try {

            ArrayList<String> list = new ArrayList<>();
            list.add("java");
            list.add("c");
            list.add("java");
            list.add("java");
            list.add("c++");
            list.add("c");
            list.add("c#");

            list = RemoveDuplicates(list);
            
            for (String s : list) {
                System.out.println(s);
            }

        } catch (Exception e) {
            System.out.println(e.toString());
        }
    }
}

/*
                 
run:
    
java
c
c++
c#
        
 */

 

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Answer 2

package javaapplication1;

import java.util.ArrayList;

public class JavaApplication1 {

    static ArrayList<String> RemoveDuplicates(ArrayList<String> list) {

        ArrayList<String> result = new ArrayList<>();

        list.stream().filter((s) -> (!result.contains(s))).forEach((s) -> {
            result.add(s);
        });
        return result;
    }

    public static void main(String[] args) {

        try {

            ArrayList<String> list = new ArrayList<>();
            list.add("java");
            list.add("c");
            list.add("java");
            list.add("java");
            list.add("c++");
            list.add("c");
            list.add("c#");
            list.add("php");
            list.add("php");

            list = RemoveDuplicates(list);
            
            for (String s : list) {
                System.out.println(s);
            }

        } catch (Exception e) {
            System.out.println(e.toString());
        }
    }
}

/*
                 
run:
    
java
c
c++
c#
php
        
 */

 

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Answer 3

package javaapplication1;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;

public class JavaApplication1 {

    public static void main(String[] args) {

        try {

            ArrayList<String> list = new ArrayList<>();
            list.add("java");
            list.add("c");
            list.add("java");
            list.add("java");
            list.add("c++");
            list.add("c");
            list.add("c#");
            list.add("php");
            list.add("php");

            Set<String> hs = new HashSet<>();
            hs.addAll(list);
            list.clear();
            list.addAll(hs);

            for (String s : list) {
                System.out.println(s);
            }

        } catch (Exception e) {
            System.out.println(e.toString());
        }
    }
}

/*
                 
run:
    
c#
c++
java
c
php
        
 */

 

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Answer 4

package javaapplication1;
 
import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.Set;
 
public class JavaApplication1 {
 
    public static void main(String[] args) {
 
        try {
 
            ArrayList<String> list = new ArrayList<>();
            list.add("java");
            list.add("c");
            list.add("java");
            list.add("java");
            list.add("c++");
            list.add("c");
            list.add("c#");
            list.add("php");
            list.add("php");
 
            Set<String> lhs = new LinkedHashSet<>(list);
            list.clear();
            list.addAll(lhs);
 
            for (String s : list) {
                System.out.println(s);
            }
 
        } catch (Exception e) {
            System.out.println(e.toString());
        }
    }
}
 
/*
                  
run:
     
java
c
c++
c#
php
         
 */

 

70+ SQL courses for beginners and professionals