Java Strings

In Java, a string is a sequence of characters, represented using double quotes. Strings are objects of the predefined String class.

Creating Strings

// Using string literals
String first = "Java";
String second = "Python";

// Using the new keyword
String third = new String("Java String");

String Operations

1. Get Length

String greet = "Hello! World";
int length = greet.length();
System.out.println("Length: " + length); // Output: 12

2. Concatenate Strings

String first = "Java ";
String second = "Programming";
String joined = first.concat(second);
System.out.println(joined); // Output: Java Programming

// Or using +
String joined2 = first + second;

3. Compare Strings

String first = "java programming";
String second = "java programming";
String third = "python programming";

System.out.println(first.equals(second)); // true
System.out.println(first.equals(third));  // false

4. Escape Characters

String example = "This is the "String" class.";
System.out.println(example); // Output: This is the "String" class.

5. Strings are Immutable

String example = "Hello! ";
example = example.concat("World");
System.out.println(example); // Output: Hello! World
// Original string "Hello! " remains unchanged

6. String Literals vs New Keyword

// Literal
String s1 = "Java"; // stored in string pool
String s2 = "Java"; // same reference as s1

// New keyword
String s3 = new String("Java"); // new object created
String s4 = new String("Java"); // different object than s3

Common String Methods