Primitive to object conversion in Java - Step-by-Step Execution

flowchart

Concept Flow - Primitive to object conversion

Start with primitive value

↓

Use wrapper class constructor or valueOf()

↓

Create wrapper object

↓

Use object in code where object needed

↓

Optionally unbox back to primitive

This flow shows how a primitive value is converted into its wrapper object using constructors or valueOf(), enabling object usage.

code_blocks

Execution Sample

Java

int num = 5;
Integer obj = Integer.valueOf(num);
System.out.println(obj);

Converts primitive int 5 to Integer object and prints it.

data_table

Execution Table

Step	Action	Primitive Value	Wrapper Object	Output
1	Declare primitive int num	5	null	none
2	Convert int to Integer using valueOf()	5	Integer(5)	none
3	Print Integer object	5	Integer(5)	5

💡 Program ends after printing the Integer object value.

search_insights

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
num	undefined	5	5	5
obj	null	null	Integer(5)	Integer(5)

key

Key Moments - 3 Insights

▶Why do we need to convert a primitive to an object?

▶Is Integer.valueOf(num) different from new Integer(num)?

▶What happens if we print the object directly?

psychology

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'obj' after step 2?

A null

B 5

C Integer(5)

D undefined

photo_camera

Concept Snapshot

Primitive to object conversion in Java:
- Use wrapper classes (Integer, Double, etc.)
- Convert with valueOf() or constructor
- Enables using primitives as objects
- Printing wrapper calls toString()
- valueOf() may cache objects for small values

contract

Full Transcript

This lesson shows how to convert a primitive type like int into its wrapper object Integer in Java. We start with a primitive int variable holding 5. Then we use Integer.valueOf(num) to create an Integer object holding the same value. This object can be used where objects are required, such as in collections or method calls. When printing the Integer object, Java calls its toString() method, displaying the primitive value inside. This process is called boxing or wrapping. Using valueOf() is preferred over new Integer() because it can reuse cached objects for small values, improving performance. The execution table traces each step, showing variable states and output. Key moments clarify why conversion is needed and differences between methods. The quiz tests understanding of variable states and conversion steps. The snapshot summarizes the concept for quick review.