How many Java string methods are there?

Patricia 31 Published: 07/21/2024

How many Java string methods are there?

I'll respond in English for this question.

In the Java programming language, there are several methods available to manipulate strings. These methods can be used to perform various operations such as concatenating strings, converting data types to strings, extracting substrings, and more. Here are some of the most commonly used string methods in Java:

equals() method: This method compares two strings for equality.

Example:

String str = "Hello";

String equalStr = "Hello";


boolean result = str.equals(equalStr);
length() method: This method returns the length of a given string.

Example:

String str = "Hello";

int length = str.length();


System.out.println("The length is: "+length);
substring() method: This method extracts a substring from the given string.

Example:

String str = "HelloWorld";

String substr = str.substring(0, 5); // extracts "Hello"
toUpperCase() and toLowerCase() methods: These methods convert strings to uppercase or lowercase.

Example:

String str = "hello";

String upperCaseStr = str.toUpperCase(); // converts to "HELLO"


String lowerCaseStr = str.toLowerCase(); // converts to "hello"
concat() method: This method concatenates two strings.

Example:

String str1 = "Hello";

String str2 = "World";


String concatStr = str1.concat(str2); // creates "HelloWorld"
replace() and replaceAll() methods: These methods replace specific characters or patterns in a string with another character or pattern.

Example:

String str = "Hello, World!";

str = str.replace(",", "-"); // replaces commas with hyphens
trim() method: This method removes whitespace from the beginning and end of a string.

Example:

String str = "   Hello   ";

String trimmedStr = str.trim(); // removes whitespace
split() method: This method splits a string into an array of substrings based on a given delimiter.

Example:

String str = "Hello,World!";

String[] splitArr = str.split(","); // splits into ["Hello", "World!"]
indexOf() and lastIndexOf() methods: These methods search for the first or last occurrence of a specified character or pattern in a string.

Example:

String str = "Hello, World!";

int index = str.indexOf(","); // finds the index of the first comma
format() method: This method formats a string based on a given format string and arguments.

Example:

String formatStr = "The number is %d";

int num = 5;


String formattedStr = String.format(formatStr, num); // creates "The number is 5"

These are just a few examples of the many methods available for working with strings in Java. There are many more methods and variations to explore!

Please let me know if you'd like me to provide more information on these or other string methods.

String methods in java with examples w3schools

I'll respond in English as per your request!

String methods in Java are used to manipulate and analyze strings. These methods can be found in the java.lang.String class, which is the most frequently used class in any Java program.

Here are some of the most commonly used string methods:

charAt(): This method returns a character at the specified index. If you specify an out-of-range value (like trying to access the 5th element in a 4-character string), it throws a StringIndexOutOfBoundsException.

Example:

String str = "Hello";

char ch = str.charAt(0); // Returns 'H'
concat(): This method returns a new string that is the result of concatenating (combining) two or more strings.

Example:

String str1 = "Hello";

String str2 = str1.concat(" World"); // Returns "Hello World"
endsWith(): This method checks if this string ends with the specified suffix, and returns a boolean value indicating whether it does so.

Example:

String str = "Hello World";

boolean result = str.endsWith("World"); // Returns true
equals(): This method compares two strings for equality. Note that this is case-sensitive; equals("hello") would not return true if your original string was "Hello".

Example:

String str1 = "Hello";

String str2 = "Goodbye";


boolean result = str1.equals(str2); // Returns false
indexOf(): This method returns the index within this string of the first occurrence of the specified substring, starting at the specified position.

Example:

String str = "Hello World";

int result = str.indexOf("o"); // Returns 4 (index of 'o' in "Hello")
length(): This method returns the length of this string.

Example:

String str = "Hello";

int length = str.length(); // Returns 5 (number of characters in "Hello")
matches(): This method tests whether a given regular expression matches this sequence.

Example:

String str = "Hello";

boolean result = str.matches("H.*"); // Returns true if matches
replace(): This method replaces the first occurrence of a substring with another string.

Example:

String str = "Hello World";

String newStr = str.replace("World", "Earth"); // Returns "Hello Earth"
split(): This method splits this string into an array of strings, using the specified regular expression as the delimiter.

Example:

String str = "Hello,Goodbye,Farewell";

String[] array = str.split(","); // Returns ["Hello", "Goodbye", "Farewell"]
startsWith(): This method checks if this string starts with the specified prefix, and returns a boolean value indicating whether it does so.

Example:

String str = "Hello World";

boolean result = str.startsWith("Hel"); // Returns true
subSequence(): This method returns a new character sequence that is a subsequence of this character sequence.

Example:

String str = "Hello World";

String subStr = str.subSequence(0, 5).toString(); // Returns "Hello"
substring(): This method returns a new string that is a substring of this string.

Example:

String str = "Hello World";

String subStr = str.substring(6); // Returns "World"
toLowerCase(): This method converts this string to lowercase, using the platform's default locale and character set to affect the conversion.

Example:

String str = "HELLO";

String newStr = str.toLowerCase(); // Returns "hello"
toUpperCase(): This method converts this string to uppercase, using the platform's default locale and character set to affect the conversion.

Example:

String str = "hello";

String newStr = str.toUpperCase(); // Returns "HELLO"
trim(): This method returns a copy of this string where leading and trailing input characters matching a specified pattern are removed.

Example:

String str = "  Hello  ";

String newStr = str.trim(); // Returns "Hello"

These are just a few examples of the many string methods available in Java. Mastering these can make your coding life easier!

(References: W3Schools - Java String Methods)

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