Default Values for Variables and Instances in Java

What are the default values assigned to variables and instances in Java?

In Java, when you declare variables and instances of classes, they are assigned default values if they are not explicitly initialized. The default values depend on the type of the variable. Here are the default values for different data types in Java:

Primitive Data Types:

1. byte: 0
2. short: 0
3. int: 0
4. long: 0L
5. float: 0.0f
6. double: 0.0d
7. char: '\u0000' (null character)
8. boolean: false

Reference Data Types:

• Object references: null

Example:

When you create an instance of a class, the instance variables (fields) of that class will be initialized to their default values if you do not provide explicit initial values. For example:

public class Example {
    int number;          // default value is 0
    boolean flag;       // default value is false
    String text;        // default value is null

    public void printValues() {
        System.out.println("Number: " + number);
        System.out.println("Flag: " + flag);
        System.out.println("Text: " + text);
    }
}

public class Main {
    public static void main(String[] args) {
        Example example = new Example();
        example.printValues();
    }
}

Output:

Number: 0
Flag: false
Text: null

In this example, the number is initialized to 0, flag to false, and text to null because they are not explicitly initialized.

Important Note:

• Local variables (variables defined within a method) do not receive default values. They must be explicitly initialized before use; otherwise, the compiler will throw an error.