Skip to main content

String Methods

Java provides many built-in methods in the String class to manipulate and analyze text.

Strings are immutable, meaning every operation returns a new String object instead of modifying the original.

Common String Methods​

MethodDescription
length()Returns the length of the string
charAt()Returns character at a specific index
substring()Extracts a part of the string
equals()Compares string values
equalsIgnoreCase()Compares strings ignoring case
toUpperCase()Converts string to uppercase
toLowerCase()Converts string to lowercase
trim()Removes leading and trailing spaces
contains()Checks if substring exists
replace()Replaces characters or substrings
startsWith()Checks if string starts with given text
endsWith()Checks if string ends with given text
indexOf()Returns index of first occurrence
lastIndexOf()Returns index of last occurrence
concat()Concatenates two strings
split()Splits string into array

Examples of String Methods

1. length()​

Returns the number of characters in the string.

String s = "Java";

System.out.println(s.length()); // 4

2. charAt()​

Returns character at a specific index.

String s = "Java";

System.out.println(s.charAt(2)); // v

3. substring()​

Extracts a portion of the string.

String s = "Java Programming";

System.out.println(s.substring(5)); // Programming

4. equals()​

Compares two string values.

String s1 = "Java";
String s2 = "Java";

System.out.println(s1.equals(s2)); // true

5. toUpperCase()​

Converts string to uppercase.

String s = "java";

System.out.println(s.toUpperCase()); // JAVA

6. toLowerCase()​

Converts string to lowercase.

String s = "JAVA";

System.out.println(s.toLowerCase()); // java

7. trim()​

Removes leading and trailing spaces.

String s = "  Java  ";

System.out.println(s.trim()); // Java

8. contains()​

Checks if substring exists.

String s = "Java Programming";

System.out.println(s.contains("Java")); // true

9. replace()​

Replaces characters or substrings.

String s = "Java";

System.out.println(s.replace('a','o')); // Jovo

10. concat()​

Joins two strings.

String s1 = "Java";
String s2 = " Programming";

System.out.println(s1.concat(s2)); // Java Programming

11. startsWith()​

Checks starting text.

String s = "Java Programming";

System.out.println(s.startsWith("Java")); // true

12. endsWith()​

Checks ending text.

String s = "Java Programming";

System.out.println(s.endsWith("Programming")); // true

13. indexOf()​

Returns index of first occurrence.

String s = "Java Programming";

System.out.println(s.indexOf("a")); // 1

14. split()​

Splits string into array.

String s = "Java Python C++";

String[] arr = s.split(" ");

for(String str : arr){
    System.out.println(str); // Java  Python  C++
}

Summary​

Important String methods:

    length()
    charAt()
    substring()
    equals()
    toUpperCase()
    toLowerCase()
    trim()
    contains()
    replace()
    concat()
    startsWith()
    endsWith()
    indexOf()
    split()

These methods are widely used for string manipulation and text processing in Java applications.