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Java Strings

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Java Strings

A String in Java is a sequence of characters, used for storing text.
Strings in Java are objects, not primitive data types.

Example:

String name = "John";

✅ Creating Strings

There are two common ways to create strings:

1. Using String Literal (Recommended)

String name = "Java";

2. Using new Keyword

String name = new String("Java");

🧵 String Output Example

public class Main {
public static void main(String[] args) {
String name = "Vipul";
System.out.println(name);
}
}

🔹 String Length

Use .length() method:

String txt = "Hello World";
System.out.println(txt.length()); // Output: 11

🔹 String Methods

Uppercase and Lowercase

String txt = "Hello";
System.out.println(txt.toUpperCase()); // HELLO
System.out.println(txt.toLowerCase()); // hello

Finding Characters

Use .indexOf() to find character or word position:

String text = "Hello Java";
System.out.println(text.indexOf("Java")); // Output: 6

🔹 Concatenation (Joining Strings)

Method 1: Using +

String first = "Hello";
String last = "Java";
System.out.println(first + " " + last);

Method 2: Using .concat()

String first = "Hello";
String last = "Java";
System.out.println(first.concat(" ").concat(last));

🔹 Special Characters (Escape Characters)

Character Meaning
\" Double quote
\\ Backslash
\n New line
\t Tab

Example:

String txt = "She said, \"Hello!\"";
System.out.println(txt);

🔹 Strings Are Immutable

Once created, a string cannot be changed.
Example:

String name = "Java";
name = name + " Programming"; // Creates a NEW string in memory
System.out.println(name);

🔹 Comparing Strings

Use .equals() instead of ==.

String a = "Java";
String b = "JAVA";

System.out.println(a.equals(b)); // false
System.out.println(a.equalsIgnoreCase(b)); // true

🔹 String Formatting

String name = "Vipul";
int age = 22;

System.out.printf("My name is %s and I am %d years old.", name, age);

⭐ Complete Example

public class Main {
public static void main(String[] args) {
String name = "Vipul";
System.out.println("Name: " + name);
System.out.println("Length: " + name.length());
System.out.println("Uppercase: " + name.toUpperCase());
System.out.println("Contains 'V'? " + name.contains("V"));
}
}

📌 Summary

Feature Details
Type Non-Primitive
Mutable? No (Strings are immutable)
Stored in String Pool (for literals)
Important Methods length(), toUpperCase(), toLowerCase(), indexOf(), concat(), equals(), contains()

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Sanjit Sinha — Web Developer | PHP • Laravel • CodeIgniter • MySQL • Bootstrap Founder, CodeCapsule — Student projects & practical coding guides. Email: info@codecapsule.in • Website: CodeCapsule.in

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