Welcome to our exploration of how to combine Java loop structures with conditional statements. By merging these elements together, your loops will be supercharged, enabling them to perform versatile actions based on different conditions.
Before charging forward, it's essential to revisit the foundation: loops. Within the vast cosmos of Java, we've navigated two primary types of loops: the for and while loops.
A for loop iterates a predetermined number of times, much like a reliable spaceship following a set route:
Java1for (int i = 0; i < 5; i++) { // Iterates five times 2 System.out.println(i); // Prints 0 to 4 3}
The while loop, on the other hand, repeats actions until a specified condition turns false:
Java1int i = 0; 2while (i < 5) { // Condition for the loop to continue 3 System.out.println(i); // Prints 0 to 4 4 i++; // Increment the counter 5}
Let's now revisit the if-else construct, which is Java's machinery for making decisions.
Java1int asteroidsDistance = 10; 2 3if (asteroidsDistance > 15) { // If this condition is true 4 System.out.println("Navigate through the asteroids."); // This line executes 5} else { 6 System.out.println("Steer clear of the asteroids."); // Else, this line executes 7}
The if-else statement enables the spaceship to decide whether to navigate through the asteroids based on their distance.
Next, consider how the for loop integrates with an if-else statement:
Java1for (int i = 0; i < 6; i++) { // Our loop will iterate 10 times 2 if (i % 2 == 0) { // If the number is divisible by 2 (Even) 3 System.out.println(i + " is even."); // It'll print "X is even." 4 } else { // If not divisible by 2 (Odd) 5 System.out.println(i + " is odd."); // It'll print "X is odd." 6 } 7} 8// Prints: 9// 0 is even. 10// 1 is odd. 11// 2 is even. 12// 3 is odd. 13// 4 is even. 14// 5 is odd.
In a similar fashion, an if-else statement can be applied within a while loop:
Java1int i = 0; 2while (i < 7) { // Our loop will iterate 10 times 3 if (i % 3 == 0) { // If the number is divisible by 3 4 System.out.println(i + " is divisible by 3."); // It'll print "X is divisible by 3." 5 } else { // If not divisible by 3 6 System.out.println(i + " is not divisible by 3."); // It'll print "X is not divisible by 3." 7 } 8 i++; // Increments the counter. 9} 10// Prints: 11// 0 is divisible by 3. 12// 1 is not divisible by 3. 13// 2 is not divisible by 3. 14// 3 is divisible by 3. 15// 4 is not divisible by 3. 16// 5 is not divisible by 3. 17// 6 is divisible by 3.
Picture this scenario: you've prepared a shopping list (an array). As you proceed through the market (akin to the for loop), you check items (the if condition) off your list. If discounts are available, you purchase the luxury goods; if not, you buy them only if they're essential.
Java1String[] shoppingList = {"Potatoes", "Tomatoes", "Luxury Martian Rice"}; 2boolean discount = true; 3 4for (String item : shoppingList) { // Iterating over the shopping list 5 // If a discount is available on a luxury item, it will be purchased. 6 // Else, if it's an essential item, it will be purchased. 7 // Otherwise, the luxury item will be skipped. 8 if (item.equals("Luxury Martian Rice") && discount) { 9 System.out.println("Buy " + item + " with discount."); 10 } else if (!item.equals("Luxury Martian Rice")) { 11 System.out.println("Buy essential " + item); 12 } else { 13 System.out.println("No discount. Skip " + item); 14 } 15}
In another setting, consider a space game. As long as you have life points (represented by a while loop), your points increase if you hit an alien (an if condition)!
Java1int score = 0; 2int lifePoints = 5; 3 4while (lifePoints > 0) { // As long as life-points remain 5 // Random generator for hit (true) or miss (false) 6 boolean isAlienHit = Math.random() > 0.5; 7 8 // If you hit, it awards 10 points. 9 // If you missed, it deducts a life point. 10 if (isAlienHit) { 11 System.out.println("Alien vessel hit! +10 points"); 12 score += 10; 13 } else { 14 System.out.println("Missed! -1 life point"); 15 lifePoints -= 1; 16 } 17} 18 19// Displays the final score when the game ends. 20System.out.println("Game Over. Your score is " + score);
By now, you would have learned how to combine Java loops and if-else statements effectively. Prepare yourself for some absorbing practice to solidify this exciting programming skill further! You're on the way to tackling more intricate problems in Java. Embark on a fulfilling journey!