How to copy an array or arraylist

Question

Think there is an array named barca[]. The array have player list. Players are determined as class. For example barca[0]=messi; messi is a player class. I want to copy barca[]. If I write barca2[]=barca[]; I copy the array but when barca2[] changes also barca[] changes. I want them independent. How can I do? ` public class Main {

public static void main(String[] args) { // TODO Auto-generated method stub Player barca[] = new Player[10]; Player barca2[] = new Player[10]; for(int i=0; i<10; i++){ barca[i] = new Player(); barca[i].id = i; } barca2 = barca; //print the arrays for(int i = 0; i<10; i++){ System.out.print(barca[i].id); } System.out.println(); for(int i = 0; i<10; i++){ System.out.print(barca2[i].id); } //change an array barca2[5].id=100; System.out.println(); //print the arrays for(int i = 0; i<10; i++){ System.out.print(barca[i].id); } System.out.println(); for(int i = 0; i<10; i++){ System.out.print(barca2[i].id); } }

}

Output:

0123456789 0123456789 012341006789 012341006789 `

which type of array is barca[] and barca2[] is int, string or etc? can you plese provide code snippet? — Girdhar Singh Rathore
– Girdhar Singh Rathore, Commented Aug 8, 2015 at 8:32
barca2 is only another reference to the same array. create a new one and assign players to it. — Shikloshi
– Shikloshi, Commented Aug 8, 2015 at 8:33
barca[] is an array. barca2[] is another array. type of array is player(class player). if there is no solution on array, I can try it on arraylist. You can think same question on arraylist. barca and barca2 are arraylist... — burak
– burak, Commented Aug 8, 2015 at 8:35

Mahesh Kapoor · Accepted Answer · 2015-08-08 10:39:04Z

It is simple to implement, if we go by Arraylist then also we get two options as listed, direct and indirect , in sample code. You may edit the object after copying the arraylist. It wouldn't affect the first arraylist. Please check full code for complete understanding.

//1. Direct: Copy player list into player1 List List<Player> player1 = new ArrayList<Player>(player); //2. Indirect using method: Copy player list into player1 List List<Player> player1 = new ArrayList<Player>(); player1.addAll(player);

You may see the complete code here. You may test the code here.

Rustam · Accepted Answer · 2015-08-08 08:38:47Z

try this:

List<String>baraca=new ArrayList<>(); List<String>temp=new ArrayList<>(); baraca.add("messi 1"); baraca.add("messi 2"); baraca.add("messi 3"); baraca.add("messi 4"); temp= new ArrayList<String>(baraca); temp.add("messi temp"); System.out.println(baraca); System.out.println(temp);

Output:

[messi 1, messi 2, messi 3, messi 4] [messi 1, messi 2, messi 3, messi 4, messi temp]

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