Strings and Arrays

September 4, 2022

Strings

Strings are immutable and they don’t change once defined. String is a class in java which allows you to initialize a string literal. String can be initialize in two different ways

Declaring strings like a normal data type
```
String name = "some name";
```
Initialializing a new class method.
```
String name = new String("some name");
```

String comes with various different methods like charAt, contains, replace, replaceAll, trim, split. We cannot use indecies to access chars in a string because they are not iterable.

String pool

String class hold a pool of already declared strings inside itself. Whenever we declare a new string at first the string pool is checked if it already contains that string. If it does than it gives the same reference back and doesn’t initialize a new string. If it doesn’t than it initialize a new string literal and adds it to the string pool.

All this works really well because strings are immutable.

Arrays

Arrays are a collection of homogenous data we can declare array in two ways

Basic syntax

dataType[] variableName = dataType[size];

dataType[] variableName = {values};

if we declare and initalize the array it will be stored in the stack

int[] numbers = {1,2,3,4,5};

if we declare it only by giving the size it will be stored in heap.

int[] numbers = int[5];

We can use a different for loop syntax to iterate over an array

for(dataType element : arrayname) {
  System.out.println(element);
}