How can I add new elements to an Array in Java

Question

I want to append elements to an array

String[] mm= {"5","4","3"};
mm.append("2");

This gives me a compile-time error

Please give me a way in which I can add elements to this array.

Answer 1

Java arrays are fixed in size. You cannot append elements in an array.

Instead, we can use an ArrayList object which implements the List interface.

An ArrayList can dynamically increase and decrease its size and thus it can append new elements to it for example :

List ll=new ArrayList("5","4","3");

ll.add("2");

Comments

ArrayList<String> myList = new ArrayList<String>(Arrays.adlist(myArray));

System.out.println("Enter elements to be added");

String element=sc.next();

myList.add(element);

myArray=myList.toArray(myList);

System.out.println(Arrays.toString(myArray));

Answer 2

We can also add elements to the array without using complex objects and collections.

String[] array1 = new String[]{"one", "two"};
String[] array2 = new String[]{"three"};
String[] array = new String[array1.length + array2.length];
System.arraycopy(array1, 0, array, 0, array1.length);
System.arraycopy(array2, 0, array, array1.length, array2.length);

Answer 3

String[] source = new String[] { "a", "b", "c", "d" };
String[] destination = new String[source.length + 2];
destination[0] = "/bin/sh";
destination[1] = "-c";
System.arraycopy(source, 0, destination, 2, source.length);

for (String parts : destination) {
  System.out.println(parts);
}