07 Java Fundamentals | If-else statements in Java | By Dummy for Dummies
Welcome back learners! It is indeed true that monkeys love bananas? But do they drink bananas? Nope. Depending on situations they consume different products. Our program that we code should be able to take different paths based on situations. For that purpose we write if-else statements in our code. These statements make our programs able to take decisions.
IF ELSE STATEMENTS
They check a condition, if it is true, they execute a specific part of code. If the condition is not true, an alternative part of code is executed.
if → Runs a code inside it when a condition is true
else → Runs an alternative code when condition is false
Let's write a simple code for it...
public class Main{
public static void main(String[] args) {
int bananas = 12;
if (bananas > 10) {
System.out.println("We have enough bananas!");
}
else {
System.out.println("We are short on bananas");
}
}
}
OUTPUT:
This will print We have enough bananas! because the condition we set is true (12>10)
With "else if"
Most of the time there are more than 2 possible outcomes. Therefore we have else if in these statements which add more conditions to block of code e.g.
public class Main{
public static void main(String[] args) {
boolean condition1 = false;
boolean condition2 = false;
boolean condition3 = false;
if(condition1){
// If condition 1 is true execute this block of code
}
else if(condition2){
// If condition 2 is true execute this block of code
}
else if(condition3){
// If condition 3 is true execute this block of code
}
else{
// If none of conditions is true execute this default block
}
}
}
OUTPUT:
==,!=,>,<,>=,<=)&&,||,!)public class Main{
public static void main(String[] args) {
int marks = 85;
if (marks > 90) { // Most specific, highest grade
System.out.println("A");
}
else if (marks > 80) { // Next level
System.out.println("B");
}
else if (marks > 70) {
System.out.println("C");
}
else {
System.out.println("Fail");
}
}
}
B Here how it works...
"NESTED" IF ELSE STATEMENTS
public class Main {
public static void main(String[] args) {
int age = 20;
boolean hasID = true;
if (age >= 18) {
if (hasID) {
System.out.println("You can enter the club.");
}
else {
System.out.println("You need an ID to enter.");
}
}
else {
System.out.println("You are too young to enter.");
}
}
}
OUTPUT:
You can enter the clubEXERCISE
Let's do an exercise for what we studied in this post. Study this code, break it down, analyze it and identify the concepts used here. It would be even better if you write down your observations and make a mini report on it.
import java.util.Scanner;
public class IfElseExercise {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("=== IF-ELSE EXERCISE ===");
System.out.print("Enter your marks (0-100): ");
int marks = input.nextInt();
System.out.print("Do you have good attendance? (true/false): ");
boolean attendance = input.nextBoolean();
// --- Simple if-else ---
if (marks >= 50) {
System.out.println("You passed the exam!");
} else {
System.out.println("You failed the exam!");
}
// --- if-else-if ladder ---
if (marks >= 90) {
System.out.println("Grade: A");
} else if (marks >= 80) {
System.out.println("Grade: B");
} else if (marks >= 70) {
System.out.println("Grade: C");
} else if (marks >= 60) {
System.out.println("Grade: D");
} else {
System.out.println("Grade: F");
}
// --- Nested if-else ---
if (marks >= 50) {
if (attendance) {
System.out.println("You are eligible for a certificate!");
} else {
System.out.println("You passed, but no certificate due to poor attendance.");
}
} else {
System.out.println("You must retake the exam.");
}
// --- Logical operators inside if ---
if (marks >= 80 && attendance) {
System.out.println("Excellent! You qualify for a scholarship.");
} else if (marks >= 80 || attendance) {
System.out.println("Good effort, but no scholarship.");
} else {
System.out.println("Work harder next time.");
}
input.close();
}
}
OUTPUT:
=== IF-ELSE EXERCISE ===
Enter your marks (0-100): 85
Do you have good attendance? (true/false): true
You passed the exam!
Grade: B
You are eligible for a certificate!
Excellent! You qualify for a scholarship.MINI PROJECT: (Grade Calculator)
Your project is to create a simple Java program that calculates a student’s grade based on percentage.
The program should ask the user to enter a percentage (0–100). According to the percentage entered, it should decide the grade using these rules:
⦿ 90–100 → Grade A
⦿ 80–89 → Grade B
⦿ 70–79 → Grade C
⦿ 60–69 → Grade D
⦿ Below 60 → Grade F
If the percentage entered is less than 0 or greater than 100, the program should print “Invalid Input.”
Finally, the program should print the percentage and the calculated grade in a neat format.
While writing the program, make sure you use:
⦿ Scanner for input
⦿ If–Else statements for conditions
⦿ Relational and logical operators where needed
⦿ printf with placeholders like %d, %.2f, and %s
EXAMPLE OUTPUT: