Else–if ladder in Java - Step-by-Step Execution

Concept Flow - Else–if ladder

Start

↓

Check Condition 1

|Yes↓

Execute Block 1

↓

End

No↓

Check Condition 2

|Yes↓

Execute Block 2

↓

End

No↓

Check Condition 3

|Yes↓

Execute Block 3

↓

End

No↓

Execute Else Block

↓

End

The else-if ladder checks conditions one by one from top to bottom. When a condition is true, its block runs and the rest are skipped. If none match, the else block runs.

Execution Sample

Java

int num = 15;
if (num < 10) {
    System.out.println("Less than 10");
} else if (num < 20) {
    System.out.println("Between 10 and 19");
} else {
    System.out.println("20 or more");
}

Checks the value of num and prints which range it falls into.

Execution Table

Step	Condition Checked	Condition Result	Block Executed	Output
1	num < 10	False	No
2	num < 20	True	Yes	Between 10 and 19
3	Else	N/A	No

💡 Condition 'num < 20' is true, so its block executes and the ladder ends.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
num	15	15	15	15

Key Moments - 2 Insights

Why does the program not check the else block when a previous condition is true?

Because once a true condition is found (see Step 2 in execution_table), the corresponding block runs and the rest of the else-if ladder is skipped.

What happens if all conditions are false?

If all conditions are false (like Step 1 and Step 2 false), the else block runs as a default action (see Step 3).

Visual Quiz - 3 Questions

Look at the execution table, what is the result of the first condition check?

A True

B Not evaluated

C False

D Error

💡 Hint

Check Step 1 under 'Condition Result' in the execution_table.

At which step does the program execute a block?

A Step 2

B Step 1

C Step 3

D None

💡 Hint

Look at 'Block Executed' column in execution_table.

If num was 25, which block would execute?

A First if block

B Else block

C Second else-if block

D No block

💡 Hint

Consider conditions in execution_table and what happens if all are false.

Concept Snapshot

Else-if ladder syntax:
if (condition1) {
  // block1
} else if (condition2) {
  // block2
} else {
  // else block
}

Checks conditions top-down, runs first true block, skips rest.
Else runs if none true.

Full Transcript

This example shows how an else-if ladder works in Java. The program checks the first condition: if num is less than 10. Since num is 15, this is false, so it moves to the next condition: if num is less than 20. This is true, so it prints 'Between 10 and 19' and stops checking further conditions. The else block is skipped because a true condition was found. If none of the conditions were true, the else block would run as a default. Variables remain unchanged during this process.