Understanding Strings in Java

Overview

• Strings: Simple to use; complex to understand fully.
• Strings store a sequence of characters.
• Different from primitive types like int, float, double, and boolean.

Creating Strings

1. Using Double Quotes
   • Syntax: String name = "Naveen";
   • String literals created using double quotes.
2. Using Character Arrays
   • You can create character arrays to store sequences of characters but less common.
3. Using new Keyword
   • Syntax: String name = new String("Naveen");
   • Creates a new String object explicitly.

Memory Allocation

• Stack Memory: Holds reference variables like name.
• Heap Memory: Holds the actual string objects.
• Java Virtual Machine (JVM) manages memory allocation.

Behind the Scenes

• String in Java is a class, not a primitive type.
  • Starts with a capital letter: String.
  • Contains methods to manipulate string data.
• When creating strings, JVM handles object creation even if syntax looks different.
  • Both String name = "Naveen"; and String name = new String("Naveen"); are valid.

String Methods

1. Concatenation: Using + Operator.
   • Example: String fullName = "Hello" + name; results in Hello Naveen.
2. Getting Character by Index: charAt Method.
   • Example: name.charAt(1) returns a from Naveen.
3. Checking Equality: equals Method.
   • Use name.equals(anotherName) to compare two strings.
4. Hash Code: hashCode Method.
   • Generates a hash code based on the string content.

Practical Examples

• Print Statements: Concatenation

  System.out.println("Hello " + name);
  

• Character at Index

  System.out.println(name.charAt(1)); // prints 'a'
  

• Concatenating Multiple Strings

  String fullName = name + " Reddy";
  System.out.println(fullName); // prints 'Naveen Reddy'
  

Key Takeaways

• Strings are more than just character sequences; they are objects of the String class.
• Memory management and object creation are handled by JVM.
• Use provided methods to manage and manipulate string data efficiently.
• Common to use syntax: String name = "value"; over new String("value");

Next Steps

• Explore different types of strings in Java.