Iterative Constructs in Java

What is the syntax for a while loop in Java?

• for (condition) { // code to be executed }

• while (condition) { // code to be executed }

• if (condition) { // code to be executed }

• do { // code to be executed } while (condition)

Answer explanation

The syntax for a while loop in Java is while (condition) { // code to be executed }

How is a for loop different from a while loop in Java?

• For loop always executes at least once, while loop may not execute at all

• The main difference is in their syntax and the way they control the iteration process.

• For loop can only be used for iterating over arrays, while loop can be used for any type of iteration

• For loop can only have a single condition for termination, while loop can have multiple conditions

Answer explanation

The main difference is in their syntax and the way they control the iteration process.

Explain the syntax for a do-while loop in Java with an example.

• int i = 1; do { System.out.println(i); i++; } while (i < 5); This will print the numbers 1 to 5.

• int i = 1; do { System.out.println(i); i++; } while (i >= 5); This will print the numbers 1 to 5.

• Example: int i = 1; do { System.out.println(i); i++; } while (i <= 5); This will print the numbers 1 to 5.

• int i = 1; do { System.out.println(i); i--; } while (i <= 5); This will print the numbers 1 to 5.

Answer explanation

The correct syntax for a do-while loop in Java is: do { //code } while (condition); The example: int i = 1; do { System.out.println(i); i++; } while (i <= 5); will print the numbers 1 to 5.

What are nested loops in Java? Provide an example.

• Example: for (int i = 1; i <= 3; i++) { for (int j = 1; j <= 5; j++) { System.out.println(i +

• + j); } }

• Example: for (int i = 1; i <= 5; i++) { for (int j = 1; j <= 3; j++) { System.out.println(i + "," + j); } }

• Example: for (int i = 1; i <= 5; i++) { for (int j = 1; j <= 3; j++) { System.out.println(j +

• + i); } }

Answer explanation

The correct example demonstrates nested loops in Java, where the outer loop runs 5 times and the inner loop runs 3 times for each iteration of the outer loop, printing the value of i and j.

How do you iterate over a list of items in a shopping cart using a for loop in Java?

• for(int i=0; i<=cart.length; i++) { // access cart[i] }

• for(int i=cart.length-1; i>=0; i--) { // access cart[i] }

• Use the following syntax: for(int i=0; i

• for(int i=1; i<=cart.length; i++) { // access cart[i] }

Answer explanation

The correct syntax for iterating over a list in Java using a for loop is: for(int i=0; i

Explain the concept of iterating over collections in Java. Give an example using loops.

• Example: LinkedList names = new LinkedList<>(); for(int i=0; i

• Example: Set names = new HashSet<>(); Iterator iterator = names.iterator(); while(iterator.hasNext()) { System.out.println(iterator.next()); }

• Example: Map names = new HashMap<>(); for(Map.Entry entry : names.entrySet()) { System.out.println(entry.getKey()); }

• Example: ArrayList names = new ArrayList<>(); for(int i=0; i

Answer explanation

The correct example demonstrates iterating over an ArrayList using a for loop, which is the concept of iterating over collections in Java.

How can you use a loop to manipulate strings in Java?

• Use a loop to manipulate integers instead of strings in Java

• Use a loop to manipulate strings in Python instead of Java

• Use a loop to directly modify the original string without iterating through each character

• Iterate through each character of the string using a loop and perform the desired manipulation on each character.

Answer explanation

The correct choice is to iterate through each character of the string using a loop and perform the desired manipulation on each character.

Write a Java code to iterate over an array of integers and find the sum of all elements using loops.

• int sum = 0; for (int i = 0; i < arr.length; i++) { sum += arr[i]; } System.out.println("Total sum: " + sum);

• int sum = 0; for (int i : arr) { sum += i; } System.out.println("Sum of elements: " + sum);

• int[] arr = {1, 2, 3, 4, 5}; int sum = 0; for (int i = 0; i < arr.length; i++) { sum += arr[i]; } System.out.println("The sum of all elements is: " + sum);

Answer explanation

The correct answer is the third option, which initializes an array of integers, iterates over the array using a for loop, and calculates the sum of all elements. It then prints the total sum.

What is the difference between a while loop and a do-while loop in Java?

• The while loop can have multiple conditions, while the do-while loop can only have one condition

• The main difference is that while loop checks the condition before executing the code inside the loop, while the do-while loop executes the code inside the loop at least once before checking the condition.

• The while loop can only be used for numeric conditions, while the do-while loop can be used for any type of condition

• The while loop is more efficient than the do-while loop in terms of memory usage

Answer explanation

The main difference is that while loop checks the condition before executing the code inside the loop, while the do-while loop executes the code inside the loop at least once before checking the condition.

How can you use nested loops to print a pattern like a triangle in Java?

• You can use a single loop to print a pattern like a triangle in Java

• You can use nested if statements instead of loops to print a pattern like a triangle in Java

• You can use a built-in Java function to directly print a triangle pattern

• You can use nested loops to print a pattern like a triangle in Java by using two nested for loops, where the outer loop controls the number of rows and the inner loop controls the number of columns to print the asterisks in the triangle pattern.

Answer explanation

You can use nested loops to print a pattern like a triangle in Java by using two nested for loops, where the outer loop controls the number of rows and the inner loop controls the number of columns to print the asterisks in the triangle pattern.