Java String

Is not a primitive type, but is sometimes treated as such in Java as the language provides some special support out of the box. Strings can be created using " around characters.

Strings are constant - their value cannot be changed after they are created.

is equivalent to:

Here are some more examples of how strings can be used:

Useful methods

indexOf

Multiple versions of this method, but can be useful for code wars style questions when working with strings.

Both of these methods also allow you to supply a second argument int fromIndex to specify the start point of the search.

indexOf(String str) : int

Returns the index of the substring str within the string.

indexOf(int ch) : int

Returns the index of the first occurrence of ch in the String, returns -1 if it doesn't exist.

lastIndexOf

Similarly to the method above, but returns the last index of a substring or character within a string. This is useful when you want to check if a substring / character only appears in the string once:

Can also use int fromIndex to specify a certain index to search from.