java append to array example

stackoverflow.com › questions › 2843366 › how-to-add-new-elements-to-an-array

The size of an array can't be modified. If you want a bigger array you have to instantiate a new one.

A better solution would be to use an ArrayList which can grow as you need it. The method ArrayList.toArray( T[] a ) gives you back your array if you need it in this form.

List<String> where = new ArrayList<String>();
where.add( ContactsContract.Contacts.HAS_PHONE_NUMBER+"=1" );
where.add( ContactsContract.Contacts.IN_VISIBLE_GROUP+"=1" );

If you need to convert it to a simple array...

String[] simpleArray = new String[ where.size() ];
where.toArray( simpleArray );

But most things you do with an array you can do with this ArrayList, too:

// iterate over the array
for( String oneItem : where ) {
    ...
}

// get specific items
where.get( 1 );

Answer from tangens on Stack Overflow

Educative

educative.io › answers › how-to-append-to-an-array-in-java

How to append to an array in Java

Use ArrayList.add() If we need a dynamic data structure that can grow and shrink automatically, ArrayList is the best option. Kickstart your programming journey with "Learn Java." Master essential concepts like input/output methods, user-defined methods, and basic data types. Build sequential, selective, and iterative programs through engaging hands-on projects. Haven’t found what you were looking for? Contact Us · We can append two arrays using Arrays.copyOf() in Java:

TutorialKart

tutorialkart.com › java › java-array › java-append-to-array

Java - Append to Array

November 23, 2020 - In this example, we will take help of ArrayList to append an element to array. We shall implement the following steps. Take input array arr1. Create an ArrayList with elements of arr1. Append the element to the ArrayList. Convert ArrayList to array.

Discussions

How to add something to primitive array in Java?

Allocate a new bigger array, copy existing values over, add the new one. You probably don't really want to be using an array for what you're doing if you're doing this a lot. More on reddit.com

r/learnprogramming

December 2, 2015

Can't append to an array of Strings inside my view

You are using ForEach in your function which returns a View. You should use the for in loop instead and it should fix it. More on reddit.com

r/SwiftUI

November 21, 2023

How to append multiple values to an array without spamming ".append( )".

You could put the values into a new array, and then call append_array on the array you want them in, with the new array as the argument. More on reddit.com

r/godot

February 13, 2023

Is there a way to insert an array at the end of a 2d array?

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r/javahelp

November 3, 2022

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Stack Overflow

stackoverflow.com › questions › 2843366 › how-to-add-new-elements-to-an-array

java - How to add new elements to an array? - Stack Overflow

Top answer

1 of 16

478

The size of an array can't be modified. If you want a bigger array you have to instantiate a new one.

A better solution would be to use an ArrayList which can grow as you need it. The method ArrayList.toArray( T[] a ) gives you back your array if you need it in this form.

List<String> where = new ArrayList<String>();
where.add( ContactsContract.Contacts.HAS_PHONE_NUMBER+"=1" );
where.add( ContactsContract.Contacts.IN_VISIBLE_GROUP+"=1" );

If you need to convert it to a simple array...

String[] simpleArray = new String[ where.size() ];
where.toArray( simpleArray );

But most things you do with an array you can do with this ArrayList, too:

// iterate over the array
for( String oneItem : where ) {
    ...
}

// get specific items
where.get( 1 );

2 of 16

124

Use a List<String>, such as an ArrayList<String>. It's dynamically growable, unlike arrays (see: Effective Java 2nd Edition, Item 25: Prefer lists to arrays).

import java.util.*;
//....

List<String> list = new ArrayList<String>();
list.add("1");
list.add("2");
list.add("3");
System.out.println(list); // prints "[1, 2, 3]"

If you insist on using arrays, you can use java.util.Arrays.copyOf to allocate a bigger array to accomodate the additional element. This is really not the best solution, though.

static <T> T[] append(T[] arr, T element) {
    final int N = arr.length;
    arr = Arrays.copyOf(arr, N + 1);
    arr[N] = element;
    return arr;
}

String[] arr = { "1", "2", "3" };
System.out.println(Arrays.toString(arr)); // prints "[1, 2, 3]"
arr = append(arr, "4");
System.out.println(Arrays.toString(arr)); // prints "[1, 2, 3, 4]"

This is O(N) per append. ArrayList, on the other hand, has O(1) amortized cost per operation.

April 18, 2025 - Appending something to an array means adding a new element to the end of that array. The method you use depends on the programming language you're working with. Here's a quick breakdown of how you can do this in some popular languages: ... Arrays in some languages like Java or C have fixed sizes, so you’ll need to use dynamic structures like ArrayList or manually create a new array with a larger size.

W3Schools

w3schools.com › java › ref_arraylist_add.asp

Java ArrayList add() Method

Arrays Loop Through an Array Real-Life Examples Multidimensional Arrays Code Challenge · Java Methods Java Method Challenge Java Method Parameters

GeeksforGeeks

geeksforgeeks.org › java › how-to-add-an-element-to-an-array-in-java

How to Add an Element to an Array in Java? - GeeksforGeeks

October 16, 2025 - The second approach is we can use ArrayList to add elements to an array because ArrayList handles dynamic resizing automatically.

iO Flood

ioflood.com › blog › java-add-to-array

Adding Elements to an Array in Java: A How-To Guide

February 27, 2024 - In this example, we create an array of integers with a length of 3 and then populate it with the numbers 1, 2, and 3. Note that the indices of the array start at 0 and go up to 2, which is the length of the array (3) minus one.

Linux Hint

linuxhint.com › append-to-an-array-in-java

Linux Hint – Linux Hint

February 28, 2023 - Linux Hint LLC, [email protected] 1210 Kelly Park Circle, Morgan Hill, CA 95037 Privacy Policy and Terms of Use

LabEx

labex.io › tutorials › java-add-elements-to-array-and-arraylist-117386

Java - Add Elements to Array and ArrayList

import java.util.Arrays; public class ArrayAppend { public static int[] appendToArray(int[] oldArr, int elementToAdd) { int[] newArr = Arrays.copyOf(oldArr, oldArr.length + 1); newArr[newArr.length - 1] = elementToAdd; return newArr; } public static void main(String[] args) { int[] arr = {1, 2, 3, 4, 5}; System.out.println("Initial Array: " + Arrays.toString(arr)); arr = appendToArray(arr, 6); arr = appendToArray(arr, 7); arr = appendToArray(arr, 8); System.out.println("After adding elements: " + Arrays.toString(arr)); } }

JanBask Training

janbasktraining.com › community › java › how-to-add-new-elements-to-an-array

How to add new elements to an array? - Java

September 2, 2025 - Use append() to add a single element. ... Use extend() to add multiple elements. ... Use insert() to add an element at a specific position. ... Use push() to add elements at the end.

JavaBeat

javabeat.net › home › how to add an element to an array in java

How to Add an Element to an Array in Java

November 30, 2023 - Create a new integer array using the “Integer” class having the size “1” greater than the formerly defined array. Apply the “for” loop such that at the specified index, the value “25” becomes appended to the new array and the ...

Quora

quora.com › How-can-I-append-a-number-into-a-java-array

How to append a number into a java array - Quora

Use java.util.ArrayListwzxhzdk:1 (or IntStream/primitive-specialized libraries) for dynamic resizing, then convert to int[] if needed. ... For many appends with primitive ints avoid boxing: use libraries such as fastutil (IntArrayList), Trove (TIntArrayList), or Eclipse Collections.

Videos

See also