Static Variables in Java

beginner· OOP · Classes & Objects

Problem

A static variable belongs to the class itself rather than to any one object, so every object shares that exact same field — changing it through one object changes what every other object sees too.

Track how many Student objects have been created using a static counter, incremented once per object.

Input

3 Student objects created

Output

Total students created: 3

Java Program

Java

class Student {
    static int totalStudents = 0;

    Student() {
        totalStudents++; // shared across every Student object, not per-instance
    }
}

public class StaticVariables {
    public static void main(String[] args) {
        new Student();
        new Student();
        new Student();
        System.out.println("Total students created: " + Student.totalStudents);
    }
}

▶ Run Code

Output

Total students created: 3

Core Logic

Incrementing a static counter inside the constructor, once per object created, tallies the total across every object without any object needing its own copy of that count.

How It Works

1static int totalStudents = 0; declares a field that belongs to the Student class itself, not to any individual object.
2The constructor Student() runs totalStudents++; every time a new object is created, regardless of which object it is.
3Because totalStudents is static, all three objects created here increment the exact same field, not three separate copies.
4Reading Student.totalStudents after creating three objects reports 3, the running total.

Creating three Student objects runs the constructor three times, so totalStudents ends at 3 — printed as "Total students created: 3".

💡

Key Point: If totalStudents were an instance variable instead of static, each object would start its own copy back at 0, and there'd be no single shared count to report.

Key Concepts

static variableshared stateconstructor

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Static Nested Class

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