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Java Program to Find String Length and Compare Strings

Learn to find string length, compare strings using equals(), and perform basic string operations in Java with practical examples and explanations.

In this program, you'll learn to work with Java strings by finding their length and comparing different strings using various methods.

To understand this example, you should have the knowledge of the following Java programming topics:

Program to Find String Length and Compare Strings

Example 1: Finding String Length

class StringLength {
    public static void main(String[] args) {
        String text1 = "Java Programming";
        String text2 = "Hello World";
        String text3 = "";

        System.out.println("String: \"" + text1 + "\"");
        System.out.println("Length: " + text1.length());

        System.out.println("\nString: \"" + text2 + "\"");
        System.out.println("Length: " + text2.length());

        System.out.println("\nString: \"" + text3 + "\"");
        System.out.println("Length: " + text3.length());
    }
}

Output:

String: "Java Programming"
Length: 16

String: "Hello World"
Length: 11

String: ""
Length: 0

Example 2: Comparing Strings

class StringComparison {
    public static void main(String[] args) {
        String str1 = "Java";
        String str2 = "Java";
        String str3 = "JAVA";
        String str4 = new String("Java");

        // Using equals() method
        System.out.println("=== Using equals() method ===");
        System.out.println("str1.equals(str2): " + str1.equals(str2));
        System.out.println("str1.equals(str3): " + str1.equals(str3));
        System.out.println("str1.equals(str4): " + str1.equals(str4));

        // Using equalsIgnoreCase() method
        System.out.println("\n=== Using equalsIgnoreCase() method ===");
        System.out.println("str1.equalsIgnoreCase(str3): " + str1.equalsIgnoreCase(str3));

        // Using == operator (not recommended for strings)
        System.out.println("\n=== Using == operator ===");
        System.out.println("str1 == str2: " + (str1 == str2));
        System.out.println("str1 == str4: " + (str1 == str4));

        // Using compareTo() method
        System.out.println("\n=== Using compareTo() method ===");
        System.out.println("str1.compareTo(str2): " + str1.compareTo(str2));
        System.out.println("str1.compareTo(str3): " + str1.compareTo(str3));
    }
}

Output:

=== Using equals() method ===
str1.equals(str2): true
str1.equals(str3): false
str1.equals(str4): true

=== Using equalsIgnoreCase() method ===
str1.equalsIgnoreCase(str3): true

=== Using == operator ===
str1 == str2: true
str1 == str4: false

=== Using compareTo() method ===
str1.compareTo(str2): 0
str1.compareTo(str3): 32

Example 3: Interactive String Operations

import java.util.Scanner;

class InteractiveStringOps {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter first string: ");
        String first = scanner.nextLine();

        System.out.print("Enter second string: ");
        String second = scanner.nextLine();

        // Display lengths
        System.out.println("\n=== String Analysis ===");
        System.out.println("First string length: " + first.length());
        System.out.println("Second string length: " + second.length());

        // Compare strings
        System.out.println("\n=== String Comparison ===");
        if (first.equals(second)) {
            System.out.println("The strings are exactly the same!");
        } else if (first.equalsIgnoreCase(second)) {
            System.out.println("The strings are the same (ignoring case)!");
        } else {
            System.out.println("The strings are different.");
        }

        // Additional operations
        System.out.println("\n=== Additional Information ===");
        System.out.println("First string in uppercase: " + first.toUpperCase());
        System.out.println("Second string in lowercase: " + second.toLowerCase());
        System.out.println("Combined length: " + (first.length() + second.length()));

        scanner.close();
    }
}

Sample Output:

Enter first string: Hello
Enter second string: hello

=== String Analysis ===
First string length: 5
Second string length: 5

=== String Comparison ===
The strings are the same (ignoring case)!

=== Additional Information ===
First string in uppercase: HELLO
Second string in lowercase: hello
Combined length: 10

Key Points

  • Use length() method to find the length of a string
  • Use equals() method to compare strings for content equality
  • Use equalsIgnoreCase() for case-insensitive comparison
  • Avoid using == operator for string comparison
  • compareTo() returns 0 if strings are equal, negative if first is smaller, positive if first is larger

Next Steps

Try modifying the program to:

  1. Check if a string is empty or null
  2. Find the longest and shortest string from multiple inputs
  3. Count specific characters in a string
  4. Reverse a string and compare with the original