Java Strings

In Java, strings are objects that represent sequences of characters. Here's an overview:

String Class:

• String in Java is represented by the java.lang.String class.
• It is immutable, meaning once created, the content of a string cannot be changed.

String Literals:

• Strings can be created using string literals enclosed in double quotes (").
• Example: "Hello, Java!".

String Concatenation:

• Strings can be concatenated using the + operator.
• Example: "Hello" + ", " + "Java!" results in "Hello, Java!".

String Methods:

• The String class provides various methods for manipulating strings, such as length(), charAt(), substring(), indexOf(), toUpperCase(), toLowerCase(), trim(), etc.

String Comparison:

• Strings can be compared using the equals() method for content comparison and the compareTo() method for lexicographical comparison.
• Example: "hello".equals("world") returns false.

Example

public class StringsExample {
    public static void main(String[] args) {
        // String literal
        String message = "Hello, Java!";

        // String concatenation
        String greeting = "Hello";
        String name = "Java";
        String sentence = greeting + ", " + name + "!";

        // String methods
        int length = message.length();
        char firstChar = message.charAt(0);
        String substring = message.substring(7);
        int index = message.indexOf(",");
        boolean startsWithHello = message.startsWith("Hello");
        boolean endsWithJava = message.endsWith("Java");

        // String comparison
        boolean isEqual = message.equals("Hello, Java!");
        int comparisonResult = message.compareTo("Hello, World!");
    }
}

Summary

Java strings are represented by the String class and are immutable. They can be created using string literals, concatenated using the + operator, and manipulated using various methods provided by the String class. Understanding strings is essential for handling text data in Java programs.