Let's say we defined an array with 20 elements. is there any way we can add some objects to the array, without any specific order of course and not just once like String[] t= {"one", "two", ..., "twenty"} ?
String[] t = new String[20];
//I know this won't work
//but something like this:
//t = {"one", "two", "three"}
//and later, add some more
//t = {"four"} ...
There are several ways to initialize the elements in an Array,
String[] t = new String[20];
t[0] = "zero";
t[1] = "one";
You can also use System.arraycopy(Object src, int srcPos, Object dest, int destPos, int length) to copy from one to another (if that's what you mean). Here concatenate Array(s) a and b to a new Array c.
String[] a = {"Hello"};
String[] b = {"World"};
String[] c = new String[a.length+b.length];
System.arraycopy(a, 0, c, 0, a.length);
System.arraycopy(b, 0, c, a.length, b.length);
System.out.println(Arrays.toString(c));
Output is
[Hello, World]
You cannot change the size of the array, but you can assign elements at specific positions.
t[3] = "four";
Re-ordering and remembering where the array is supposed to end may or may not become cumbersome.
For more flexible "arrays", people like to use java.util.ArrayList.
You can assign values like this
t[10] = "ten";
t[11] = "eleven";
It is better to use ArrayList so there is no need of initializing the size first and it is dynamic too.
Unfortunately, that's not exactly how java arrays work. To instantiate and initialize an array use the syntax...
String[] t = new String[20];
t[0] = "One";
t[1] = "Two";
or,
String[] t = {"One", "Two"};
If you want more control over the array the I'd recommend using an ArrayList object instead where you can add, remove, change, sort the items in the array. For example,
ArrayList t = new ArrayList();
t.add("One");
t.add("Two");
t.remove(0);
ArrayList is a good option for ArrayList supports dynamic arrays that can grow as needed.
With arrays you can add elements by specifying the specific position you want to add
like adding in position 4 we can do something like array[3] = "four"
but for more control arraylist is recommended
Unfortunately, Array should be used in below way only
String[] t = new String[20];
t[0] = "One";
t[1] = "Two";
...
t[19] = "Twenty";
You can try using arrayList: You need not even specify how many elements are expected while initializing.
ArrayList t = new ArrayList();
t.add("One");
t.add("Two");
...
t.add("Twenty");
ArrayList?