Java if, if-else and the if-else-if Ladder: ICSE Class 8 with Outputs

Understand if, if-else and the if-else-if Ladder in Java

if (n > 0)
    System.out.println("Positive");

if (n % 2 == 0)
    System.out.println(n + " is even");
else
    System.out.println(n + " is odd");

if (m >= 90)
    g = 'A';
else if (m >= 75)
    g = 'B';
else if (m >= 60)
    g = 'C';
else
    g = 'D';

if, if-else and the if-else-if Ladder in Java: key facts

Shapes of decision

if	one path
if-else	two paths
if-else-if ladder	many paths

The first true condition in a ladder wins.

Syntax rules

• •Condition in brackets
• •No semicolon after the condition
• •Braces for several statements
• •else has no condition

A ; after if () makes the if do nothing.

Grade ladder

m >= 90	A
m >= 75	B
m >= 60	C
else	D

90 gives A; 60 gives C; 59 gives D.

How to answer if, if-else and the if-else-if Ladder in Java questions

1. 1Write the conditions from the strictest downwards in a ladder.
2. 2Put each condition in brackets and leave out the semicolon.
3. 3Use braces if an if or else has more than one statement.
4. 4Trace a value through the conditions from the top and stop at the first true one.
5. 5Test boundary values such as 90, 89, 75 and 60.

if, if-else and the if-else-if Ladder in Java in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Tricks to remember if, if-else and the if-else-if Ladder in Java

Short memory aids. Say each one aloud once, then use it on a question the same day.

• First true wins

  In a ladder only the first true branch runs.

  Use it when: Ladders.

• No semicolon after if

  if (x > 0); makes the if do nothing.

  Use it when: Syntax.

if, if-else and the if-else-if Ladder in Java: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

int k = 4;
if (k > 2)
    k = k + 3;
k = k * 2;
System.out.println(k);

Where students lose marks in if, if-else and the if-else-if Ladder in Java

The slips examiners see most often, and what to write instead.

• ✗Mistake: Semicolon after the condition

  It ends the if immediately.

  Wrong working

  if (x > 0); print;

  Right working

  if (x > 0) print;

  ✓Do this: No semicolon after ).

  Usually costs: 1 to 2 marks

• ✗Mistake: Putting two statements under an if without braces

  Only the first belongs to the if.

  Wrong working

  if (m > 5) m = m + 1; m = m * 2; treated as both inside.

  Right working

  Use { } around both.

  ✓Do this: Use braces for more than one statement.

  Usually costs: 1 mark

• ✗Mistake: Wrong order in a ladder

  The first true condition wins.

  Wrong working

  Checking >= 60 before >= 90.

  Right working

  Check >= 90 first.

  ✓Do this: Strictest condition first.

  Usually costs: 1 mark

Practice questions on if, if-else and the if-else-if Ladder in Java

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQBoard level

   In an if-else-if ladder, what happens after one condition is true?
   (a) All remaining conditions are checked (b) The rest are skipped (c) The program stops (d) The first condition runs again

   Hint

   First true wins.

   Answer

   (b) The rest are skipped.

2. Q2 · 2 marks · Short answerBoard level

   Write an if-else statement that prints Pass if marks >= 40 and Fail otherwise. (2 marks)

   Hint

   No semicolon after the condition.

   Answer

   if (marks >= 40) System.out.println("Pass"); else System.out.println("Fail");

3. Q3 · 3 marks · Short answerHarder board level

   With n = -4, what does this print? if (n > 0) System.out.println("Positive"); System.out.println("Done"); Explain. (3 marks)

   Hint

   Which line belongs to the if?

   Answer

   It prints only Done. -4 > 0 is false so Positive is skipped, and the second println is outside the if and always runs.

4. Q4 · 4 marks · Long answerHarder board level

   Write an if-else-if ladder for the sign of n printing Positive, Negative or Zero, and trace n = 0 and n = -7. (4 marks)

   Hint

   Two conditions.

   Answer

   if (n > 0) System.out.println("Positive"); else if (n < 0) System.out.println("Negative"); else System.out.println("Zero"); For n = 0 neither condition is true so Zero is printed; for -7, n < 0 is true so Negative is printed.

5. Q5 · 4 marks · Long answerHOTS / competency

   A ladder is written: if (m >= 60) g = 'C'; else if (m >= 75) g = 'B'; else if (m >= 90) g = 'A'; else g = 'D'; Find g for 95 and explain the design fault. (4 marks)

   Hint

   The first condition is true for 95.

   Answer

   For 95, m >= 60 is true, so g = C and the rest are skipped. The ladder is in the wrong order: the strictest condition must come first (m >= 90, then 75, then 60), otherwise every mark of 60 or above gets C.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.What does an if-else-if ladder do?Show answer

   Chooses one of many paths by checking conditions from the top.

2. 2.Is a semicolon allowed after if (condition)?Show answer

   No.

3. 3.What makes several statements part of an if?Show answer

   Braces { }.

4. 4.What does else need?Show answer

   No condition; it runs when the if is false.

5. 5.What is the grade for 90?Show answer

   A.

6. 6.What type must a condition be?Show answer

   true or false.

if, if-else and the if-else-if Ladder in Java: frequently asked questions