Java provides a variety of String methods that allow you to manipulate and process text easily. Below is a list of commonly used String methods, along with their syntax and examples.
String Methods in Java
| Method | Syntax | Description | Example |
|---|---|---|---|
| charAt(int index) | str.charAt(index) | Returns the character at the specified index. | String str = “Java”; char c = str.charAt(1); // ‘a’ |
| length() | str.length() | Returns the number of characters in the string. | String str = “Hello”; int len = str.length(); // 5 |
| toLowerCase() | str.toLowerCase() | Returns a new string with all characters in lowercase. | String str = “JAVA”; String lower = str.toLowerCase(); // “java” |
| toUpperCase() | str.toUpperCase() | Returns a new string with all characters in uppercase. | String str = “java”; String upper = str.toUpperCase(); // “JAVA” |
| substring(int start) | str.substring(start) | Returns a substring starting from the given index. | String str = “Hello”; String sub = str.substring(1); // “ello” |
| substring(int start, int end) | str.substring(start, end) | Returns a substring from start to end index (exclusive). | String str = “Hello”; String sub = str.substring(1, 4); // “ell” |
| contains(CharSequence seq) | str.contains(seq) | Checks if the string contains the specified sequence. | String str = “Java programming”; boolean result = str.contains(“program”); // true |
| equals(Object obj) | str.equals(obj) | Compares two strings for equality (case-sensitive). | String str1 = “hello”; String str2 = “hello”; boolean result = str1.equals(str2); // true |
| equalsIgnoreCase(String str) | str.equalsIgnoreCase(str) | Compares two strings for equality, ignoring case differences. | String str1 = “hello”; String str2 = “HELLO”; boolean result = str1.equalsIgnoreCase(str2); // true |
| indexOf(int ch) | str.indexOf(ch) | Returns the index of the first occurrence of the specified character. | String str = “Hello”; int index = str.indexOf(‘e’); // 1 |
| lastIndexOf(int ch) | str.lastIndexOf(ch) | Returns the index of the last occurrence of the specified character. | String str = “Hello”; int index = str.lastIndexOf(‘l’); // 3 |
| replace(CharSequence target, CharSequence replacement) | str.replace(target, replacement) | Replaces all occurrences of the target sequence with the replacement sequence. | String str = “hello”; String result = str.replace(“e”, “a”); // “hallo” |
| replaceAll(String regex, String replacement) | str.replaceAll(regex, replacement) | Replaces each substring that matches the regular expression with the given replacement. | String str = “ab123cd”; String result = str.replaceAll(“\\d”, “#”); // “ab###cd” |
| replaceFirst(String regex, String replacement) | str.replaceFirst(regex, replacement) | Replaces the first substring that matches the regular expression with the given replacement. | String str = “ab123cd”; String result = str.replaceFirst(“\\d”, “#”); // “ab#23cd” |
| trim() | str.trim() | Removes leading and trailing whitespace from the string. | String str = ” hello “; String result = str.trim(); // “hello” |
| split(String regex) | str.split(regex) | Splits the string into an array of substrings based on the given regular expression. | String str = “apple,banana,orange”; String[] result = str.split(“,”); // [“apple”, “banana”, “orange”] |
| startsWith(String prefix) | str.startsWith(prefix) | Checks if the string starts with the given prefix. | String str = “Java”; boolean result = str.startsWith(“J”); // true |
| endsWith(String suffix) | str.endsWith(suffix) | Checks if the string ends with the given suffix. | String str = “Java”; boolean result = str.endsWith(“a”); // true |
| concat(String str) | str.concat(str) | Concatenates the specified string to the end of the current string. | String str1 = “Hello”; String result = str1.concat(” World”); // “Hello World” |
| isEmpty() | str.isEmpty() | Checks if the string is empty (length 0). | String str = “”; boolean result = str.isEmpty(); // true |
| matches(String regex) | str.matches(regex) | Checks if the string matches the given regular expression. | String str = “abc123”; boolean result = str.matches(“\\w+”); // true |
| valueOf(boolean b) | String.valueOf(b) | Converts the boolean value to a string. | boolean b = true; String str = String.valueOf(b); // “true” |
| valueOf(char c) | String.valueOf(c) | Converts the character to a string. | char c = ‘A’; String str = String.valueOf(c); // “A” |
| valueOf(int i) | String.valueOf(i) | Converts the integer to a string. | int i = 123; String str = String.valueOf(i); // “123” |
| valueOf(long l) | String.valueOf(l) | Converts the long value to a string. | long l = 123L; String str = String.valueOf(l); // “123” |
| valueOf(float f) | String.valueOf(f) | Converts the float value to a string. | float f = 10.5f; String str = String.valueOf(f); // “10.5” |
| valueOf(double d) | String.valueOf(d) | Converts the double value to a string. | double d = 12.34; String str = String.valueOf(d); // “12.34” |
| toCharArray() | str.toCharArray() | Converts the string into a new character array. | String str = “Hello”; char[] arr = str.toCharArray(); // [‘H’, ‘e’, ‘l’, ‘l’, ‘o’] |
| intern() | str.intern() | Returns a canonical representation for the string. | String str = “java”; String internStr = str.intern(); |
| regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len) | str.regionMatches(ignoreCase, toffset, other, ooffset, len) | Compares two substrings for equality. | String str1 = “Hello”; String str2 = “hell”; boolean result = str1.regionMatches(true, 0, str2, 0, 4); // true |
| codePointAt(int index) | str.codePointAt(index) | Returns the Unicode code point value of the character at the specified index. | String str = “Hello”; int codePoint = str.codePointAt(0); // 72 |
| codePointBefore(int index) | str.codePointBefore(index) | Returns the Unicode code point value of the character before the specified index. | String str = “Hello”; int codePoint = str.codePointBefore(1); // 72 |
