In Java, is a String an array of chars?

Question

I want to know, if a String is a collection. I have read around but am still quite confused.

Answer 1

Strings are immutable objects representing a character sequence (CharSequence is one of the interfaces implemented by String). Main difference to char arrays and collections of chars: String cannot be modified, it's not possible (ignoring reflection) to add/remove/replace characters.

Internally they are represented by a char array with an offset and length (this allows to create lightweight substrings, using the same char arrays).

Example: ['F','o','o','H','e','l','l','o',' ','W','o','r','l','d'], offset=3, count=5 = "Hello".

Answer 2

strings are object of class String and it's not a Collection as well. It is implemented on top of char array. You can see it in the below code snippet:

public final class String implements 
        java.io.Serializable, Comparable<String>, CharSequence
    {           
    private final char value[];

Answer 3

No, it's not a collection in that it does not implement the Collection<E> interface.

Conceptually, it is an immutable sequence of characters (and implements the CharSequence interface).

Internally, the String class is likely to use an array of chars, although I am pretty sure the spec does not mandate that.

Answer 4

No, A string is an object of class String

The String class represents character strings. All string literals in Java programs, such as "abc", are implemented as instances of this class....

A String represents a string in the UTF-16 format in which supplementary characters are represented by surrogate pairs (see the section Unicode Character Representations in the Character class for more information). Index values refer to char code units, so a supplementary character uses two positions in a String.

Answer 5

No it's not an Array or a Collection. However there is a convenient method if you need a char array and you have a String - namely String.toCharArray(); you could use it like this

    // Prints the String "Hello, World!" as a char[].
    System.out.println(Arrays.toString("Hello, World!".toCharArray()));

Answer 6

No, a String is an immutable string of characters, and the class extends Object directly and does not implement any of the Collection interfaces. Really, that's the basic answer.

However, there's a lot going on under the covers in the runtime--there's a whole collection of cached strings held by the JVM and in its most primitive representation, yeah, a String is basically an array of characters (meaning it's a bunch of memory addresses pointing to representations of characters). Still, once you go below the definition of String as it's defined as a class, you can keep going until you get to the point that you're just talking about organized combinations of ones and zeroes.

I'm guessing here, but I imagine you posed the question because you're studying this and an instructor said something about a String being an array of characters. While technically correct, that's really confusing because the two concepts exists at completely different levels of abstraction.

Answer 7

String Class is just a class which allows you to create objects of strings. Like all classes it makes easy the use of these objects using its owns methods. An array of char is an string, but its methods are relative to arrays or the elements of the array.

So for example if you want to look for the position of a carácter in an string of a class String then you use a method called IndexOf. But if you want to find a character in an array of char, then you would have to do it manually using loops.