.png)
Working with Strings in Java
 |
| Java - String Methods |
Introduction :
Strings are sequences of characters and are widely used in Java programming. Java provides a String class with various built-in methods to handle string operations efficiently.
String Class :
In Java, strings are objects of the String class. Every string variable is an instance of this class, and Java provides multiple methods to manipulate strings, including:
concat(): Concatenates two strings.
length(): Returns the length of a string.
charAt(): Retrieves a character at a specific index.
substring(): Extracts a portion of a string.
repeat(): Repeats a string multiple times.
String Concatenation :
String concatenation combines two or more strings into a single string.
Using concat() Method :
The concat() method appends one string to another. However, it only works with string values.
class Main {
public static void main(String[] args) {
String str1 = "Hello ";
String str2 = "World";
String result = str1.concat(str2);
System.out.println(result);
}
}
Output:
Hello World
Concatenating a string with a non-string data type using concat() results in an error.
Using + Operator :
The + operator can concatenate multiple strings and other primitive data types, converting non-string values into strings automatically.
class Main {
public static void main(String[] args) {
String str1 = "Hello ";
String str2 = "World ";
int num = 3;
String result = str1 + str2 + num;
System.out.println(result);
}
}
Output:
Hello World 3
Length of a String :
The length() method returns the number of characters in a string.
class Main {
public static void main(String[] args) {
String name = "Rahul";
int length = name.length();
System.out.println(length);
}
}
Output:
5
String Indexing :
Each character in a string has an index, starting from 0. The charAt() method retrieves the character at a specified index.
class Main {
public static void main(String[] args) {
String name = "Ram";
char firstLetter = name.charAt(0);
System.out.println(firstLetter);
}
}
Output :
String Slicing :
Extracting a portion of a string is called slicing. The substring() method is used for this purpose.
Extracting a Substring :
The substring(startIndex, endIndex) method retrieves a substring from startIndex to endIndex - 1.
class Main {
public static void main(String[] args) {
String message = "Welcome to Java";
String part = message.substring(0, 5);
System.out.println(part);
}
}
Output:
WelcoSlicing Till End :
If endIndex is omitted, slicing continues to the end of the string.
class Main {
public static void main(String[] args) {
String message = "Welcome to Java";
String part = message.substring(11);
System.out.println(part);
}
}
Output:
JavaString Repetition :
The repeat() method repeats a string n times.
class Main {
public static void main(String[] args) {
String str = "Ram";
System.out.println(str.repeat(2));
}
}
Output:
RamRamSummary
concat(): Joins two strings.length(): Returns the number of characters in a string.charAt(): Retrieves a character at a specified index.substring(): Extracts a substring.repeat(): Repeats a string multiple times.
.png)