Instance variable, Local variable, static variable and global variable

Instance variable:
we can declare variable in the class level not in the method level.
inside the method we can initialize the value for that variable declared.
Example:
public class School {

// Instance(Object) variable
int std;
int age;

public static void main(String[] args) {

    // Object or Instance
    School akshaya = new School();
    akshaya.std = 10;
    akshaya.age = 15;

    System.out.println(akshaya.std);
    System.out.println(akshaya.age);

School kiruthika = new School();
kiruthika.std = 7;
kiruthika.age = 12;
System.out.println(kiruthika.std);
System.out.println(kiruthika.age);
School karthick = new School();
karthick.std = 12;
karthick.age = 17;

    System.out.println(karthick.std);
    System.out.println(karthick.age);

Local variable:
It is inside the class and also inside the method that is called a local variable.
we cannot able to access from the different method.

Static variable:
It is initialized in the class level not a method level.
It is common for all the objects. we can use that variable in all the object if needed.
example:
public class School {
// static variable
static String school_name = "abc hr sec school";
public static void main(String[] args) {
School akshaya = new School();
System.out.println(School.school_name);
}
}

Global variable:
We can access the variable in side the any methodor all method.

Example for all:
package moduleOne;

public class School {

// Instance(Object) variable
int std;
int age;

// static variable
static String school_name = "abc hr sec school";

// Global variable
String leave = "10th standard";

public static void main(String[] args) {

    // Object or Instance
    School akshaya = new School();
    akshaya.std = 10;
    akshaya.age = 15;

    System.out.println(akshaya.std);
    System.out.println(akshaya.age);
    akshaya.calculate(60, 70, 50, 80, 95);
    System.out.println(School.school_name);

    School kiruthika = new School();
    kiruthika.std = 7;
    kiruthika.age = 12;

    System.out.println(kiruthika.std);
    System.out.println(kiruthika.age);
    kiruthika.calculate(40, 75, 85, 50, 75);

    School karthick = new School();
    karthick.std = 12;
    karthick.age = 17;

    System.out.println(karthick.std);
    System.out.println(karthick.age);
    karthick.calculate(45, 56, 59, 40, 94);
}

public void calculate(int tamil, int english, int maths, int science, int social) {

    // Local variable
    int total = tamil + english + maths + science + social;
    System.out.println(total);
}

}