Static vs non-static behavior in Java - Visual Side-by-Side Comparison

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Concept Flow - Static vs non-static behavior

Start Program

↓

Create Object?

No→Access Static Member

↓

Use Class Name

↓

Access Non-Static Member

↓

Static Member Shared

↓

Member Uses Object Data

↓

End Program

↓

End Program

The program starts, decides if an object is created. Non-static members need an object; static members belong to the class and can be accessed without an object.

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Execution Sample

Java

class Demo {
  static int count = 0;
  int id;
  Demo(int id) { this.id = id; count++; }
  void show() { System.out.println(id + ":" + count); }
}

Demo d1 = new Demo(1);
d1.show();
Demo d2 = new Demo(2);
d2.show();

Creates two objects with ids 1 and 2, increments static count, and shows id and count for each object.

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Execution Table

Step	Action	id (object field)	count (static field)	Output
1	Create d1 with id=1	1	1
2	d1.show() prints	1	1	1:1
3	Create d2 with id=2	2	2
4	d2.show() prints	2	2	2:2
5	End of program	-	-	-

💡 Program ends after showing values for both objects.

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Variable Tracker

Variable	Start	After Step 1	After Step 3	Final
d1.id	undefined	1	1	1
d2.id	undefined	undefined	2	2
count	0	1	2	2

key

Key Moments - 3 Insights

▶Why does 'count' increase even though we don't change it directly in main?

▶Why can we access 'count' without an object?

▶Why does 'show()' print different 'id' but same 'count'?

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Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'count' after creating the second object?

A 1

B 2

C 0

D Undefined

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Concept Snapshot

Static vs Non-Static in Java:
- Static members belong to the class, shared by all objects.
- Non-static members belong to individual objects.
- Static fields keep one copy; non-static fields have separate copies per object.
- Access static members via class name; non-static via object.
- Constructors can modify static fields to track all instances.

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Full Transcript

This visual trace shows how static and non-static members behave in Java. When creating objects, the non-static field 'id' is unique per object, while the static field 'count' is shared and increments with each new object. The execution table tracks each step: creating objects, showing values, and how static count changes globally. Key moments clarify why static fields are shared and how they differ from non-static fields. The quiz tests understanding of these differences by referencing the execution steps and variable changes.