Enhanced for loop in Java - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an enhanced for loop in Java?

An enhanced for loop is a simpler way to iterate over arrays or collections without using an index variable. It automatically goes through each element one by one.

beginner

Syntax of an enhanced for loop in Java?

for (Type variable : collection) { // code using variable }

intermediate

Can you modify the elements of an array using an enhanced for loop?

No, the enhanced for loop provides a copy of each element, so modifying the loop variable does not change the original array elements.

beginner

What types of data structures can you use with an enhanced for loop?

You can use arrays and any class that implements the Iterable interface, like ArrayList, LinkedList, HashSet, etc.

beginner

Example: How to print all elements of an int array using enhanced for loop?

int[] numbers = {1, 2, 3}; for (int num : numbers) { System.out.println(num); }

What does the enhanced for loop automatically handle?

A Creating new arrays

B Indexing through elements

C Declaring variables

D Sorting elements

The enhanced for loop automatically handles indexing through elements, so you don't need to manage the index manually.

Which of these can NOT be used directly in an enhanced for loop?

A HashMap

B ArrayList

C Array

D LinkedList

HashMap does not implement Iterable directly, so you cannot use it directly in an enhanced for loop without calling keySet(), values(), or entrySet().

What happens if you try to modify the loop variable inside an enhanced for loop?

A Original array elements change

B Loop stops immediately

C Compilation error

D Loop variable changes but original elements stay the same

The loop variable is a copy of each element, so modifying it does not affect the original array or collection elements.

Which keyword is used in the enhanced for loop syntax?

A in

B of

C :

D ->

The colon ':' is used in the enhanced for loop syntax to separate the variable and the collection.

What is the main advantage of using an enhanced for loop?

A Simpler and less error-prone code

B Supports multi-threading

C Allows modifying collection size

D Faster execution

The enhanced for loop makes code simpler and less error-prone by removing the need to manage indexes manually.

Explain how an enhanced for loop works and when you would use it.

Think about how it replaces the traditional for loop with index.

Write a simple Java code snippet using an enhanced for loop to print all elements of a String array.

Use for (String item : array) and System.out.println inside the loop.