Java ArrayList addAll()

Java ArrayList [Java ArrayList] Java ArrayList

addAll() arraylist

addAll() 

arraylist.addAll(int index, Collection c)

arraylist ArrayList

  • index-
  • c -

index

true

null NullPointerException

index IndexOutOfBoundsException

ArrayList addAll()

import java.util.ArrayList;

class Main {
    public static void main(String[] args){
       
        //
        ArrayList<Integer> primeNumbers = new ArrayList<>();
        //
        primeNumbers.add(3);
        primeNumbers.add(5);
        System.out.println("Prime Numbers: " + primeNumbers);

        //
        ArrayList<Integer> numbers = new ArrayList<>();
        numbers.add(1);
        numbers.add(2);

        // primeNumbers numbers
        numbers.addAll(primeNumbers);
        System.out.println("Numbers: " + numbers);
    }
}

Prime Numbers: [3, 5]
Numbers: [1, 2, 3, 5]

primeNumbers numbers

:

numbers.addAll(primeNumbers);

addAll() indexprimeNumbers numbers

:

import java.util.ArrayList;

class Main {
    public static void main(String[] args){
        ArrayList<String> languages1 = new ArrayList<>();
        languages1.add("Java");
        languages1.add("Python");
        System.out.println("ArrayList 1: " + languages1);

        //
        ArrayList<String> languages2 = new ArrayList<>();
        languages2.add("JavaScript");
        languages2.add("C");
        System.out.println("ArrayList 2: " + languages2);

        // 1 languages1 languages2
        languages2.addAll(1, languages1);
        System.out.println(" ArrayList 2: " + languages2);
    }
}

:

ArrayList 1[JavaPython]
ArrayList 2[JavaScriptC]
 ArrayList 2[JavaScriptJavaPythonC]

:

languages2.addAll(1, languages1);

addAll() index languages1 languages 1

Set

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

class Main {
    public static void main(String[] args){

        // Stringhashset
        HashSet<String> set = new HashSet<>();

        // hashset
        set.add("Java");
        set.add("Python");
        set.add("JavaScript");
        System.out.println("HashSet: " + set);

        //
        ArrayList<String> list = new ArrayList<>();

        //
        list.add("English");
        System.out.println(" ArrayList: " + list);

        //  hashset
        list.addAll(set);
        System.out.println(" ArrayList: " + list);
    }
}

Set: [Java, JavaScript, Python]
 ArrayList: [English]
 ArrayList: [English, Java, JavaScript, Python]

set hashset list 

list.addAll(set);

addAll() hashset index

Java ArrayList [Java ArrayList] Java ArrayList