Strings

Published Jul 30, 2021Updated Jun 30, 2022

Strings in Java are objects that can hold a sequence of characters contained within a pair of double quotes ("). It is not a primitive data type.

Strings can either be compared by value via method (e.g., .equals()) or by reference, or location in memory, (e.g., ==) via operator.

Example

Java strings provide a way to store text such as words, sentences, or whole paragraphs. They can be any length and may contain letters, numbers, symbols, and spaces:

import java.util.*;

class StringExample {
  public static void main(String[] args) {
    // Using a string literal
    System.out.println("Codecademy");

    // Creating a String variable
    String address = "575 Broadway #5, New York, NY 10012";
    System.out.println(address);
  }
}

This will output the following:

Codecademy
575 Broadway #5, New York, NY 10012

Strings

.charAt(): Returns the character at the given index in the string.
.codePointAt(): Returns the Unicode value at the given index in the string.
.codePointBefore(): Returns the Unicode value before the given index in the string.
.codePointCount(): Returns the number of Unicode values in specified range of a string.
.compareTo(): Returns 0 if two strings are equal in Unicode value. Otherwise, the lexicographical difference is returned.
.compareToIgnoreCase(): Returns 0 if two strings are equal in Unicode value, regardless of character case. Otherwise, the lexicographical difference is returned.
.concat(): Returns a string that is the concatenation of the given strings.
.contains(): Returns true if a sequence of characters exists in a given string, otherwise false.
.contentEquals(): Returns true if the sequence of characters in the string is equal to the content of the specified string. If not, returns false.
.copyValueOf(): Returns a string with characters copied from an array.
.endsWith(): Returns true if a string ends with a given suffix, otherwise false.
.equals(): Returns true if two strings are equal in value and false otherwise.
.equalsIgnoreCase(): Compares two strings in a case-insensitive manner.
.format(): Returns a string with additional arguments in a specifically defined format.
.getBytes(): Encodes the string into an array of bytes that represent the characters in the string.
.hashCode(): Returns an integer hash code value for the object on which it is invoked.
.indexOf(): Returns the zero-indexed position of the first occurrence of the given character(s) in a string.
.intern(): Creates an exact copy of a string located in the heap memory and stores it in the string constant pool.
.isEmpty(): Returns true if a string has no content, otherwise false.
.join(): Returns a new string composed of the elements joined together with the specified delimiter.
.lastIndexOf(): Searches a string for a specified value and returns the position of the match.
.length(): Returns the number of characters contained in a string.
.matches(): Checks whether a string matches a given regular expression.
.regionMatches(): Tests if two string regions are equal.
.replace(): Returns a new string where all instances of a given value are switched with a new value.
.replaceAll(): Replaces every matching subsequence in the input sequence with the specified replacement string.
.replaceFirst(): Replaces the first matching substring in a string with the specified replacement string.
.split(): Splits a string into an array of substrings based on a delimiter pattern.
.startsWith(): Returns true if a string starts with a given character sequence and false otherwise.
.subSequence(): Returns a character sequence from a string.
.substring(): Returns a part of the string specified through a starting index and an optional ending index.
.toCharArray(): Returns an new character array from a given string.
.toLowerCase(): Converts a string to lowercase characters.
.toUpperCase(): Returns a given string in all uppercase letters
.trim(): Removes leading and trailing whitespace from a string.
.valueOf(): Returns the string representation of a given value.