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Difference between String and Character array in Java

Last Updated : 25 Jul, 2024

Unlike C/C++ Character arrays and Strings are two different things in Java. Both Character Arrays and Strings are a collection of characters but are different in terms of properties.

Differences between Strings and Character Arrays:

PropertyStringCharacter Array
DefinitionA sequence of characters is represented as a single data type.A sequential collection of characters of the data type char.
MutabilityImmutable - Once created, their values cannot be changed.Mutable - Individual characters can be modified.
Built-in FunctionsProvides many built-in functions like substring(), charAt(), length(), etc.No built-in functions for operations.
ConcatenationStrings can be concatenated using the + operator.Cannot use + for concatenation; must use loops or utility methods.
Access CharactersCharacters can be accessed using the charAt() method.Characters can be accessed using array indexing ([]).
Memory StorageCan be stored anywhere in memory, typically managed by the JVM.Elements are stored contiguously in increasing memory locations.
String Constant PoolStrings are stored in String Constant Pool if they are string literals or interned, otherwise they are stored in the heap.Stored in the Heap.
SecurityNot preferred for storing passwords due to immutability and persistence in the String Pool.Preferred for storing passwords as they can be explicitly cleared after use.
ConversionCan be converted to a Character Array using the toCharArray() method. <br> Example: String s = "GEEKS"; char[] ch = s.toCharArray();Can be converted to a String using the String constructor. <br> Example: char[] a = {'G', 'E', 'E', 'K', 'S'}; String A = new String(a);

Key Differences:

  • Immutability vs. Mutability:
    • String: Immutable, meaning once a String object is created, it cannot be altered. This property makes them suitable for use as keys in hashmaps or for string manipulation without side effects.
    • Character Array: Mutable, allowing changes to individual characters, making them more suitable for scenarios where frequent modifications are required, like password storage.
  • Built-in Functions:
    • String: Java provides a rich set of built-in methods for various operations, including searching, splitting, and replacing substrings.
    • Character Array: Lacks built-in methods, so manual handling or utility methods are required for similar operations.
  • Memory Management:
    • String: Stored in the String Constant Pool when it is defined as literal, in double quotes - "Hello, World!". This allows for reuse of common strings, thus saving memory.
      If it is created by using new keyword via constructors new String("Hello, World!") they are stored in normal heap area.
    • Character Array: Stored in the heap, providing direct and contiguous access to memory locations.
  • Security Considerations:
    • String: Due to immutability and persistence in the String Pool, they can be a security risk for sensitive data like passwords.
    • Character Array: Since they can be explicitly modified and cleared, they are preferred for storing sensitive information.
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