What is String in Java?
String is used to store text values in Java.
String is a non-primitive data type in Java.
Create String
Strings are created using double quotes.
public class Main {
public static void main(String[] args) {
String name = "CodeVyro";
System.out.println(name);
}
}
Output
CodeVyro
String Concatenation
Concatenation means joining two strings together.
public class Main {
public static void main(String[] args) {
String first = "Java";
String second = "Programming";
System.out.println(first + " " + second);
}
}
Output
Java Programming
concat() Method
concat() method joins strings together.
public class Main {
public static void main(String[] args) {
String text1 = "Hello ";
String text2 = "World";
System.out.println(text1.concat(text2));
}
}
Output
Hello World
String Length
length() method returns total characters in string.
public class Main {
public static void main(String[] args) {
String text = "Hello";
System.out.println(text.length());
}
}
Output
5
Uppercase and Lowercase
toUpperCase() converts string to uppercase and toLowerCase() converts string to lowercase.
public class Main {
public static void main(String[] args) {
String text = "Java";
System.out.println(text.toUpperCase());
System.out.println(text.toLowerCase());
}
}
Output
JAVA java
charAt() Method
charAt() returns character at specific index.
public class Main {
public static void main(String[] args) {
String text = "Java";
System.out.println(text.charAt(2));
}
}
Output
v
substring() Method
substring() extracts part of a string.
public class Main {
public static void main(String[] args) {
String text = "Programming";
System.out.println(text.substring(3));
}
}
Output
gramming
String Comparison
equals() method compares two strings.
public class Main {
public static void main(String[] args) {
String a = "Java";
String b = "Java";
System.out.println(a.equals(b));
}
}
Output
true
contains() Method
contains() checks whether string contains text.
public class Main {
public static void main(String[] args) {
String text = "Java Programming";
System.out.println(text.contains("Java"));
}
}
Output
true
indexOf() Method
indexOf() returns index position of character.
public class Main {
public static void main(String[] args) {
String text = "CodeVyro";
System.out.println(text.indexOf("V"));
}
}
Output
4
Escape Characters
Escape characters are used for special formatting.
| Escape Character | Description |
|---|---|
| \n | New Line |
| \t | Tab Space |
| \" | Double Quote |
| \\ | Backslash |
Escape Character Example
public class Main {
public static void main(String[] args) {
System.out.println("Java\nProgramming");
}
}
Output
Java Programming
Important String Methods
| Method | Description |
|---|---|
| length() | Returns string length |
| charAt() | Returns character |
| substring() | Extracts string |
| equals() | Compares strings |
| contains() | Checks text availability |
| toUpperCase() | Converts to uppercase |
| toLowerCase() | Converts to lowercase |
| indexOf() | Returns index position |
Complete Java String Program
public class Main {
public static void main(String[] args) {
String name = "CodeVyro";
System.out.println(name);
System.out.println(name.length());
System.out.println(name.toUpperCase());
System.out.println(name.charAt(2));
}
}
Output
CodeVyro 8 CODEVYRO d
Advantages of Strings
- Easy text handling
- Built in methods available
- Supports text manipulation
- Improves program readability
Best Practices
- Use meaningful variable names
- Use equals() for comparison
- Avoid unnecessary string concatenation
- Use StringBuilder for heavy operations
Conclusion
Strings are one of the most important concepts in Java. They help developers manage and manipulate text efficiently. Understanding string methods is essential for Java development.