Static Method vs Non- Static Method in Java

In Java, methods can be declared as either static or non-static, also known as instance methods. The main differences between static and non-static methods are as follows:

1. Static methods belong to the class, while non-static methods belong to instances of the class. This means that you can call a static method without creating an object of the class, but you need an object to call a non-static method.

2. Static methods can access only static variables and other static methods, whereas non-static methods can access both static and non-static variables and methods of the class.

3. Static methods are shared among all instances of the class, while non-static methods are specific to each instance of the class.

4. Static methods cannot be overridden in subclasses, while non-static methods can be overridden.

Here's an example to illustrate the difference between static and non-static methods:

java
public class MyClass {
    private static int staticVar;
    private int instanceVar;
    
    public static void staticMethod() {
        // Can only access staticVar and other static methods
        staticVar = 10;
    }
    
    public void instanceMethod() {
        // Can access both staticVar and instanceVar, and other methods
        staticVar = 5;
        instanceVar = 3;
    }
}

In the example above, the staticMethod() is a static method and can be called like this: MyClass.staticMethod(). The instanceMethod() is a non-static method and needs to be called on an instance of the class: MyClass obj = new MyClass(); obj.instanceMethod();.

In summary, use static methods when you don't need to access instance variables or methods and when you want to share a method among all instances of the class. Use non-static methods when you need to access instance variables or methods and when you want each instance to have its own copy of the method.