Iterator pattern in LLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare the Iterator interface method.

LLD

interface Iterator {
    boolean [1]();
}

Drag options to blanks, or click blank then click option'

AhasNext

Bnext

Cremove

Dreset

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing next instead of hasNext

Using remove which is optional

The hasNext method checks if there are more elements to iterate over.

2fill in blank

medium

Complete the code to return the next element in the iterator.

LLD

public Object [1]() {
    if (!hasNext()) {
        throw new NoSuchElementException();
    }
    return collection.get(currentIndex++);
}

Drag options to blanks, or click blank then click option'

Aremove

BhasNext

Cnext

Dreset

Attempts:

3 left

💡 Hint

Common Mistakes

Using hasNext instead of next

Trying to remove element here

The next method returns the next element and advances the iterator.

3fill in blank

hard

Fix the error in the iterator implementation to correctly check for more elements.

LLD

public boolean hasNext() {
    return currentIndex [1] collection.size();
}

Drag options to blanks, or click blank then click option'

A<

B<=

C>

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using >= or > which causes errors

Using <= which is off by one

The hasNext method should return true if currentIndex is less than collection size.

4fill in blank

hard

Fill both blanks to implement a simple iterator for an array.

LLD

class ArrayIterator implements Iterator {
    private Object[] items;
    private int [1] = 0;

    public ArrayIterator(Object[] items) {
        this.items = items;
    }

    public boolean hasNext() {
        return [2] < items.length;
    }
}

Drag options to blanks, or click blank then click option'

AcurrentIndex

Bindex

Cpointer

Dposition

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently

Not initializing the index variable

The variable currentIndex tracks the current position in the array for iteration.

5fill in blank

hard

Fill all three blanks to complete the iterator's next method.

LLD

public Object [1]() {
    if (!hasNext()) {
        throw new NoSuchElementException();
    }
    return items[[2]++];
}

public void [3]() {
    [2] = 0;
}

Drag options to blanks, or click blank then click option'

Anext

BcurrentIndex

Creset

DhasNext

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing method names

Not incrementing index properly

Missing reset method

The next method returns the current item and increments the index. The reset method sets the index back to zero.