Type casting in Java - Step-by-Step Execution

Concept Flow - Type casting

Start with a value

↓

Check target type

↓

Perform cast

↓

Use casted value

↓

End

Type casting changes a value from one type to another, either automatically or by explicit instruction.

Execution Sample

Java

int i = 100;
byte b = (byte) i;
System.out.println(b);

This code converts an int value to a byte using explicit casting and prints the result.

Execution Table

Step	Action	Value Before	Cast Type	Value After	Output
1	Declare int i	N/A	int	100	N/A
2	Cast int i to byte b	100	byte	100	N/A
3	Print byte b	100	byte	100	100

💡 Program ends after printing the casted byte value.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
i	undefined	100	100	100
b	undefined	undefined	100	100

Key Moments - 2 Insights

Why do we need to use (byte) before i when assigning to b?

Because int is larger than byte, Java requires explicit cast to avoid data loss, as shown in step 2 of the execution_table.

What happens if the int value is too big for byte?

The value wraps around due to overflow, changing the stored byte value. This is not shown here but is important to remember.

Visual Quiz - 3 Questions

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

A 0

B 100

C -100

D undefined

💡 Hint

Check the 'Value After' column in row for step 2.

At which step is the value printed to the console?

A Step 1

B Step 2

C Step 3

D No step prints

💡 Hint

Look at the 'Output' column in the execution_table.

If we remove (byte) cast, what will happen?

A Compilation error due to incompatible types

B Runtime error occurs

C Code compiles and runs fine

D Value of b becomes zero

💡 Hint

Java requires explicit cast when assigning int to byte, see step 2 explanation.

Concept Snapshot

Type casting changes a value's type.
Implicit cast happens automatically if safe.
Explicit cast uses (type) before value.
Casting from larger to smaller type may lose data.
Example: byte b = (byte) intValue;

Full Transcript

This example shows type casting in Java. We start with an int variable i set to 100. Then we explicitly cast i to a byte and assign it to b. Finally, we print b. The execution table shows each step: declaring i, casting to b, and printing. The variable tracker shows how i and b change. Key points: explicit cast is needed when going from int to byte to avoid errors. If the int value is too large, casting can cause overflow. The quiz checks understanding of value changes and casting rules.