Java Notes

Array Interview Questions

Comprehensive collection of Java array interview questions and answers covering conceptual, coding, and tricky questions asked in TCS, Infosys, Wipro, Amazon, and Google interviews.

This comprehensive collection covers conceptual, coding, and tricky output-based questions frequently asked in Java interviews at all levels — from freshers to experienced professionals.

Section 1: Conceptual Questions

Q1: What is an array in Java?

Answer: An array in Java is a fixed-size, contiguous data structure that stores multiple elements of the same data type. It is an object that resides in heap memory, accessed via a reference variable. Arrays provide O(1) random access using integer indices starting from 0.

Key characteristics:

Fixed size (cannot grow/shrink after creation)
Homogeneous (same data type for all elements)
Zero-indexed (first element at index 0)
Object in Java (inherits from java.lang.Object)
Contiguous memory allocation for elements

Q2: Where are arrays stored in memory?

Answer: Arrays in Java have two parts:

Reference variable — stored in stack memory (if local) or heap (if instance/static field)
Actual array object — always stored in heap memory

When you write int[] arr = new int[5]:

arr (reference) goes on stack — takes 4/8 bytes (32-bit/64-bit JVM)
The array object (5 ints + header) goes on heap — takes 20+ bytes (5×4 + object header)

Q3: What is the difference between `length`, `length()`, and `size()`?

Answer:

Property/Method	Used With	Example
`length`	Arrays (property, no parentheses)	`arr.length`
`length()`	String (method)	`str.length()`
`size()`	Collections (method)	`list.size()`

java example

int[] arr = {1, 2, 3};
String str = "Hello";
ArrayList<Integer> list = new ArrayList<>();

System.out.println(arr.length);    // 3
System.out.println(str.length());  // 5
System.out.println(list.size());   // 0

Q4: What are default values of array elements?

Answer:

Type	Default
byte, short, int, long	0
float, double	0.0
boolean	false
char	'\u0000'
Object references	null

These defaults are assigned automatically by JVM when using new. Array literals don't need defaults since values are explicitly provided.

Q5: Can we change the size of an array after creation?

Answer: No. Arrays are fixed-size in Java. Once created with new int[5], the size is permanently 5. To "resize":

Create a new array of desired size
Copy elements from old to new array
Assign the new array to the variable

java example

int[] arr = {1, 2, 3};
arr = Arrays.copyOf(arr, 6); // Creates new array, copies, and reassigns
// Original 3-element array becomes eligible for garbage collection

Use ArrayList if dynamic sizing is needed.

Q6: What is the difference between `int[] a` and `int a[]`?

Answer: Both are valid declarations for an integer array. The difference matters when declaring multiple variables:

java example

int[] a, b;    // Both a AND b are arrays
int a[], b;    // Only a is an array, b is a regular int!

The first style (int[] a) is preferred in Java because the type (int[]) is clearly separated from the variable name.

Q7: Can we create an array of size 0?

Answer: Yes! new int[0] creates a valid array object with length 0. It's useful as:

Return value when no results are found (instead of null)
Empty varargs parameter
Placeholder that avoids NullPointerException

Example

int[] empty = new int[0]; System.out.println(empty.length); // 0 — valid System.out.println(empty instanceof int[]); // true

Q8: What is an anonymous array in Java?

Answer: An array created without being assigned to a named variable, typically passed directly to a method:

java example

// Anonymous array
printArray(new int[]{1, 2, 3, 4, 5});

// You cannot use shorthand syntax for anonymous arrays:
// printArray({1, 2, 3}); // COMPILE ERROR

Q9: Explain array cloning in Java.

Answer: clone() creates a shallow copy of an array:

For primitive arrays — it effectively creates a deep copy (values are copied)
For object arrays — only references are copied; objects themselves are shared

Example

int[] original = {1, 2, 3}; int[] copy = original.clone(); copy[0] = 99; // original[0] is still 1 — independent copy for primitives String[] names = {"Alice", "Bob"}; String[] namesCopy = names.clone(); // namesCopy[0] and names[0] point to the SAME String object // But since Strings are immutable, this is safe in practice

Q10: What is ArrayStoreException?

Answer: Thrown when you try to store an object of incompatible type in an object array:

Example

Object[] arr = new String[3]; // Allowed (String IS-A Object) arr[0] = "Hello"; // OK arr[1] = 42; // ArrayStoreException! Integer is not String

This happens because the actual array type is String[], even though the reference type is Object[].

Section 2: Coding Questions with Solutions

Q11: Write a program to find the third largest element without sorting.

java example

public class ThirdLargest {
    public static void main(String[] args) {
        int[] arr = {12, 13, 1, 10, 34, 1, 50};
        
        int first = Integer.MIN_VALUE;
        int second = Integer.MIN_VALUE;
        int third = Integer.MIN_VALUE;
        
        for (int num : arr) {
            if (num > first) {
                third = second;
                second = first;
                first = num;
            } else if (num > second && num != first) {
                third = second;
                second = num;
            } else if (num > third && num != second && num != first) {
                third = num;
            }
        }
        
        System.out.println("Array: " + java.util.Arrays.toString(arr));
        System.out.println("Third largest: " + third);
    }
}

Output

Array: [12, 13, 1, 10, 34, 1, 50]
Third largest: 13

Q12: Find the element that appears odd number of times.

java example

public class OddOccurrence {
    public static void main(String[] args) {
        int[] arr = {2, 3, 5, 4, 5, 2, 4, 3, 5, 2, 4, 4, 2};
        
        int result = 0;
        for (int num : arr) {
            result ^= num; // XOR cancels out pairs
        }
        
        System.out.println("Array: " + java.util.Arrays.toString(arr));
        System.out.println("Element appearing odd times: " + result);
    }
}

Output

Array: [2, 3, 5, 4, 5, 2, 4, 3, 5, 2, 4, 4, 2]
Element appearing odd times: 5

Explanation: XOR of a number with itself is 0. All numbers appearing even times cancel out, leaving only the odd-occurring number.

Q13: Separate even and odd numbers in an array.

Example

import java.util.Arrays; public class SeparateEvenOdd { public static void main(String[] args) { int[] arr = {12, 34, 45, 9, 8, 90, 3, 7, 56}; System.out.println("Original: " + Arrays.toString(arr)); int left = 0, right = arr.length - 1; while (left < right) { while (left < right && arr[left] % 2 == 0) left++; while (left < right && arr[right] % 2 != 0) right--; if (left < right) { int temp = arr[left]; arr[left] = arr[right]; arr[right] = temp; left++; right--; } } System.out.println("Separated: " + Arrays.toString(arr)); } }

Output

Original: [12, 34, 45, 9, 8, 90, 3, 7, 56]
Separated: [12, 34, 56, 90, 8, 9, 3, 7, 45]

Q14: Find the subarray with given sum (non-negative numbers).

Example

public class SubarraySum { public static void main(String[] args) { int[] arr = {1, 4, 20, 3, 10, 5}; int targetSum = 33; int start = 0, currentSum = 0; for (int end = 0; end < arr.length; end++) { currentSum += arr[end]; while (currentSum > targetSum && start <= end) { currentSum -= arr[start]; start++; } if (currentSum == targetSum) { System.out.println("Array: " + java.util.Arrays.toString(arr)); System.out.println("Subarray with sum " + targetSum + " found:"); System.out.println("Indices " + start + " to " + end); System.out.print("Elements: "); for (int i = start; i <= end; i++) { System.out.print(arr[i] + " "); } System.out.println(); return; } } System.out.println("No subarray found"); } }

Output

Array: [1, 4, 20, 3, 10, 5]
Subarray with sum 33 found:
Indices 2 to 4
Elements: 20 3 10

Section 3: Predict the Output Questions

Q15: What is the output?

Example

public class OutputQuestion1 { public static void main(String[] args) { int[] a = {1, 2, 3, 4, 5}; int[] b = a; b[2] = 99; System.out.println(a[2]); } }

Output

Explanation: b = a copies the reference, not the array. Both a and b point to the same array object. Changing b[2] changes the shared array.

Q16: What is the output?

Example

public class OutputQuestion2 { public static void main(String[] args) { int[] arr = new int[5]; System.out.println(arr[0]); System.out.println(arr); } }

Output

0
[I@1b6d3586

Explanation: arr[0] prints default value 0. arr prints the default toString() of the array object: [I means 1D int array, @ followed by hashcode in hex.

Q17: What is the output?

java example

public class OutputQuestion3 {
    static void modify(int[] arr) {
        arr = new int[]{10, 20, 30};
    }
    
    public static void main(String[] args) {
        int[] arr = {1, 2, 3};
        modify(arr);
        System.out.println(java.util.Arrays.toString(arr));
    }
}

Output

[1, 2, 3]

Explanation: Inside modify(), arr = new int[]{10, 20, 30} reassigns the LOCAL parameter to a new array. The original reference in main() is unaffected. If the method had done arr[0] = 99, the original WOULD be modified.

Q18: What is the output?

java example

public class OutputQuestion4 {
    public static void main(String[] args) {
        int[] a = {1, 2, 3};
        int[] b = {1, 2, 3};
        System.out.println(a == b);
        System.out.println(a.equals(b));
        System.out.println(java.util.Arrays.equals(a, b));
    }
}

Output

false
false
true

Explanation:

a == b: Compares references — different objects, so false
a.equals(b): Arrays don't override Object.equals(), so it compares references — false
Arrays.equals(a, b): Compares content element by element — true

Section 4: Tricky and Advanced Questions

Q19: What happens with negative array size?

Example

// int[] arr = new int[-5]; // Throws NegativeArraySizeException at RUNTIME (not compile time!)

The compiler cannot detect this because size could be a variable computed at runtime.

Q20: Can an array hold different types?

Example

// Primitive array — NO, strictly one type // Object array — YES, through polymorphism Object[] mixed = new Object[4]; mixed[0] = "Hello"; // String mixed[1] = 42; // Integer (autoboxed) mixed[2] = 3.14; // Double (autoboxed) mixed[3] = new int[]{1}; // Even arrays!

Q21: Maximum array size in Java?

Answer: Theoretically Integer.MAX_VALUE (2,147,483,647), but practically limited by:

Available heap memory (-Xmx setting)
JVM implementation (many cap at Integer.MAX_VALUE - 5 or Integer.MAX_VALUE - 8)
Attempting too large causes OutOfMemoryError

Q22: How to convert array to ArrayList and vice versa?

Example

import java.util.*; public class ConversionDemo { public static void main(String[] args) { // Array to ArrayList String[] arr = {"A", "B", "C"}; List<String> list = new ArrayList<>(Arrays.asList(arr)); System.out.println("ArrayList: " + list); // ArrayList to Array String[] back = list.toArray(new String[0]); System.out.println("Array: " + Arrays.toString(back)); } }

Output

ArrayList: [A, B, C]
Array: [A, B, C]

Q23: Why does `Arrays.asList()` return a fixed-size list?

Answer: Arrays.asList() returns a java.util.Arrays$ArrayList (inner class), NOT java.util.ArrayList. This wrapper is backed by the original array, so:

You CAN set() elements (modifies the original array too)
You CANNOT add() or remove() — throws UnsupportedOperationException

To get a modifiable list: new ArrayList<>(Arrays.asList(arr))

Q24: Explain covariance in arrays.

Example

// Array covariance: String[] IS-A Object[] Object[] objArr = new String[3]; // ALLOWED (covariant) objArr[0] = "Hello"; // OK // objArr[1] = 42; // ArrayStoreException at RUNTIME! // Compare with generics: List<String> is NOT List<Object> // List<Object> list = new ArrayList<String>(); // COMPILE ERROR (invariant)

Arrays are covariant (allows SubType[] where SuperType[] is expected) which can lead to runtime errors. Generics are invariant, catching errors at compile time.

Q25: What is the time and space complexity of common array operations?

Operation	Time Complexity	Notes
Access by index	O(1)	Direct address calculation
Search (unsorted)	O(n)	Linear search
Search (sorted)	O(log n)	Binary search
Insert at end	O(1)	If space available
Insert at position	O(n)	Shift elements
Delete at position	O(n)	Shift elements
Sort	O(n log n)	Arrays.sort()
Copy	O(n)	Must visit each element

Common Mistakes

Using == to compare arrays — compares references, not content
Forgetting that clone() is shallow for object arrays
Not checking for null before accessing array properties
ArrayStoreException when using covariant arrays
Off-by-one errors — valid indices are 0 to length-1
Confusing fixed-size list from Arrays.asList() with regular ArrayList
Integer overflow when computing mid in binary search: use low + (high - low) / 2
Modifying array passed to method without documenting the side effect

Best Practices

Use Arrays.equals() for comparison, Arrays.deepEquals() for multi-dimensional
Prefer ArrayList when size is dynamic
Use enhanced for loop when index isn't needed
Document array semantics — what each index represents
Return empty arrays instead of null from methods
Use Arrays.copyOf() instead of manual copy loops
Validate inputs — check for null, empty, and bounds
Consider immutability — use Collections.unmodifiableList() after wrapping
Profile before optimizing — premature optimization is the root of all evil
Know your algorithm complexities — choose the right approach for the data size

Interview Questions (Quick-Fire Round)

Q1: Is array a primitive or reference type? → Reference type (object)

Q2: Can array size be a variable? → Yes, any non-negative int expression

Q3: What class do arrays extend? → java.lang.Object

Q4: Is length a method or field? → Field (public final int)

Q5: Can you serialize arrays? → Yes, all arrays implement Serializable

Q6: Thread-safe? → No, arrays need external synchronization

Q7: Can arrays implement interfaces? → Yes, they implement Cloneable and Serializable

Q8: Fastest way to copy? → System.arraycopy() (native method)

Q9: How to sort descending? → Use Integer[] with Arrays.sort(arr, Collections.reverseOrder())

Q10: Null vs empty array? → Null has no object; empty (new int[0]) is a valid object with length 0

Exam Focus

Revise definitions, diagrams, examples, and short-answer points for Array Interview Questions.

Interview Use

Prepare one clear explanation, one practical example, and one common mistake for this Java Master Course topic.

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Java Notes

Array Interview Questions

Comprehensive collection of Java array interview questions and answers covering conceptual, coding, and tricky questions asked in TCS, Infosys, Wipro, Amazon, and Google interviews.

This comprehensive collection covers conceptual, coding, and tricky output-based questions frequently asked in Java interviews at all levels — from freshers to experienced professionals.

Section 1: Conceptual Questions

Q1: What is an array in Java?

Key characteristics:

Fixed size (cannot grow/shrink after creation)
Homogeneous (same data type for all elements)
Zero-indexed (first element at index 0)
Object in Java (inherits from java.lang.Object)
Contiguous memory allocation for elements

Q2: Where are arrays stored in memory?

Answer: Arrays in Java have two parts:

Reference variable — stored in stack memory (if local) or heap (if instance/static field)
Actual array object — always stored in heap memory

When you write int[] arr = new int[5]:

arr (reference) goes on stack — takes 4/8 bytes (32-bit/64-bit JVM)
The array object (5 ints + header) goes on heap — takes 20+ bytes (5×4 + object header)

Q3: What is the difference between `length`, `length()`, and `size()`?

Answer:

Property/Method	Used With	Example
`length`	Arrays (property, no parentheses)	`arr.length`
`length()`	String (method)	`str.length()`
`size()`	Collections (method)	`list.size()`

java example

int[] arr = {1, 2, 3};
String str = "Hello";
ArrayList<Integer> list = new ArrayList<>();

System.out.println(arr.length);    // 3
System.out.println(str.length());  // 5
System.out.println(list.size());   // 0

Q4: What are default values of array elements?

Answer:

Type	Default
byte, short, int, long	0
float, double	0.0
boolean	false
char	'\u0000'
Object references	null

These defaults are assigned automatically by JVM when using new. Array literals don't need defaults since values are explicitly provided.

Q5: Can we change the size of an array after creation?

Answer: No. Arrays are fixed-size in Java. Once created with new int[5], the size is permanently 5. To "resize":

Create a new array of desired size
Copy elements from old to new array
Assign the new array to the variable

java example

int[] arr = {1, 2, 3};
arr = Arrays.copyOf(arr, 6); // Creates new array, copies, and reassigns
// Original 3-element array becomes eligible for garbage collection

Use ArrayList if dynamic sizing is needed.

Q6: What is the difference between `int[] a` and `int a[]`?

Answer: Both are valid declarations for an integer array. The difference matters when declaring multiple variables:

java example

int[] a, b;    // Both a AND b are arrays
int a[], b;    // Only a is an array, b is a regular int!

The first style (int[] a) is preferred in Java because the type (int[]) is clearly separated from the variable name.

Q7: Can we create an array of size 0?

Answer: Yes! new int[0] creates a valid array object with length 0. It's useful as:

Return value when no results are found (instead of null)
Empty varargs parameter
Placeholder that avoids NullPointerException

Example

int[] empty = new int[0]; System.out.println(empty.length); // 0 — valid System.out.println(empty instanceof int[]); // true

Q8: What is an anonymous array in Java?

Answer: An array created without being assigned to a named variable, typically passed directly to a method:

java example

// Anonymous array
printArray(new int[]{1, 2, 3, 4, 5});

// You cannot use shorthand syntax for anonymous arrays:
// printArray({1, 2, 3}); // COMPILE ERROR

Q9: Explain array cloning in Java.

Answer: clone() creates a shallow copy of an array:

For primitive arrays — it effectively creates a deep copy (values are copied)
For object arrays — only references are copied; objects themselves are shared

Example

Q10: What is ArrayStoreException?

Answer: Thrown when you try to store an object of incompatible type in an object array:

Example

Object[] arr = new String[3]; // Allowed (String IS-A Object) arr[0] = "Hello"; // OK arr[1] = 42; // ArrayStoreException! Integer is not String

This happens because the actual array type is String[], even though the reference type is Object[].

Section 2: Coding Questions with Solutions

Q11: Write a program to find the third largest element without sorting.

java example

public class ThirdLargest {
    public static void main(String[] args) {
        int[] arr = {12, 13, 1, 10, 34, 1, 50};
        
        int first = Integer.MIN_VALUE;
        int second = Integer.MIN_VALUE;
        int third = Integer.MIN_VALUE;
        
        for (int num : arr) {
            if (num > first) {
                third = second;
                second = first;
                first = num;
            } else if (num > second && num != first) {
                third = second;
                second = num;
            } else if (num > third && num != second && num != first) {
                third = num;
            }
        }
        
        System.out.println("Array: " + java.util.Arrays.toString(arr));
        System.out.println("Third largest: " + third);
    }
}

Output

Array: [12, 13, 1, 10, 34, 1, 50]
Third largest: 13

Q12: Find the element that appears odd number of times.

java example

public class OddOccurrence {
    public static void main(String[] args) {
        int[] arr = {2, 3, 5, 4, 5, 2, 4, 3, 5, 2, 4, 4, 2};
        
        int result = 0;
        for (int num : arr) {
            result ^= num; // XOR cancels out pairs
        }
        
        System.out.println("Array: " + java.util.Arrays.toString(arr));
        System.out.println("Element appearing odd times: " + result);
    }
}

Output

Array: [2, 3, 5, 4, 5, 2, 4, 3, 5, 2, 4, 4, 2]
Element appearing odd times: 5

Explanation: XOR of a number with itself is 0. All numbers appearing even times cancel out, leaving only the odd-occurring number.

Q13: Separate even and odd numbers in an array.

Example

Output

Original: [12, 34, 45, 9, 8, 90, 3, 7, 56]
Separated: [12, 34, 56, 90, 8, 9, 3, 7, 45]

Q14: Find the subarray with given sum (non-negative numbers).

Example

Output

Array: [1, 4, 20, 3, 10, 5]
Subarray with sum 33 found:
Indices 2 to 4
Elements: 20 3 10

Section 3: Predict the Output Questions

Q15: What is the output?

Example

public class OutputQuestion1 { public static void main(String[] args) { int[] a = {1, 2, 3, 4, 5}; int[] b = a; b[2] = 99; System.out.println(a[2]); } }

Output

Explanation: b = a copies the reference, not the array. Both a and b point to the same array object. Changing b[2] changes the shared array.

Q16: What is the output?

Example

public class OutputQuestion2 { public static void main(String[] args) { int[] arr = new int[5]; System.out.println(arr[0]); System.out.println(arr); } }

Output

0
[I@1b6d3586

Explanation: arr[0] prints default value 0. arr prints the default toString() of the array object: [I means 1D int array, @ followed by hashcode in hex.

Q17: What is the output?

java example

public class OutputQuestion3 {
    static void modify(int[] arr) {
        arr = new int[]{10, 20, 30};
    }
    
    public static void main(String[] args) {
        int[] arr = {1, 2, 3};
        modify(arr);
        System.out.println(java.util.Arrays.toString(arr));
    }
}

Output

[1, 2, 3]

Q18: What is the output?

java example

public class OutputQuestion4 {
    public static void main(String[] args) {
        int[] a = {1, 2, 3};
        int[] b = {1, 2, 3};
        System.out.println(a == b);
        System.out.println(a.equals(b));
        System.out.println(java.util.Arrays.equals(a, b));
    }
}

Output

false
false
true

Explanation:

a == b: Compares references — different objects, so false
a.equals(b): Arrays don't override Object.equals(), so it compares references — false
Arrays.equals(a, b): Compares content element by element — true

Section 4: Tricky and Advanced Questions

Q19: What happens with negative array size?

Example

// int[] arr = new int[-5]; // Throws NegativeArraySizeException at RUNTIME (not compile time!)

The compiler cannot detect this because size could be a variable computed at runtime.

Q20: Can an array hold different types?

Example

Q21: Maximum array size in Java?

Answer: Theoretically Integer.MAX_VALUE (2,147,483,647), but practically limited by:

Available heap memory (-Xmx setting)
JVM implementation (many cap at Integer.MAX_VALUE - 5 or Integer.MAX_VALUE - 8)
Attempting too large causes OutOfMemoryError

Q22: How to convert array to ArrayList and vice versa?

Example

Output

ArrayList: [A, B, C]
Array: [A, B, C]

Q23: Why does `Arrays.asList()` return a fixed-size list?

Answer: Arrays.asList() returns a java.util.Arrays$ArrayList (inner class), NOT java.util.ArrayList. This wrapper is backed by the original array, so:

You CAN set() elements (modifies the original array too)
You CANNOT add() or remove() — throws UnsupportedOperationException

To get a modifiable list: new ArrayList<>(Arrays.asList(arr))

Q24: Explain covariance in arrays.

Example

Arrays are covariant (allows SubType[] where SuperType[] is expected) which can lead to runtime errors. Generics are invariant, catching errors at compile time.

Q25: What is the time and space complexity of common array operations?

Operation	Time Complexity	Notes
Access by index	O(1)	Direct address calculation
Search (unsorted)	O(n)	Linear search
Search (sorted)	O(log n)	Binary search
Insert at end	O(1)	If space available
Insert at position	O(n)	Shift elements
Delete at position	O(n)	Shift elements
Sort	O(n log n)	Arrays.sort()
Copy	O(n)	Must visit each element

Common Mistakes

Using == to compare arrays — compares references, not content
Forgetting that clone() is shallow for object arrays
Not checking for null before accessing array properties
ArrayStoreException when using covariant arrays
Off-by-one errors — valid indices are 0 to length-1
Confusing fixed-size list from Arrays.asList() with regular ArrayList
Integer overflow when computing mid in binary search: use low + (high - low) / 2
Modifying array passed to method without documenting the side effect

Best Practices

Use Arrays.equals() for comparison, Arrays.deepEquals() for multi-dimensional
Prefer ArrayList when size is dynamic
Use enhanced for loop when index isn't needed
Document array semantics — what each index represents
Return empty arrays instead of null from methods
Use Arrays.copyOf() instead of manual copy loops
Validate inputs — check for null, empty, and bounds
Consider immutability — use Collections.unmodifiableList() after wrapping
Profile before optimizing — premature optimization is the root of all evil
Know your algorithm complexities — choose the right approach for the data size

Interview Questions (Quick-Fire Round)

Q1: Is array a primitive or reference type? → Reference type (object)

Q2: Can array size be a variable? → Yes, any non-negative int expression

Q3: What class do arrays extend? → java.lang.Object

Q4: Is length a method or field? → Field (public final int)

Q5: Can you serialize arrays? → Yes, all arrays implement Serializable

Q6: Thread-safe? → No, arrays need external synchronization

Q7: Can arrays implement interfaces? → Yes, they implement Cloneable and Serializable

Q8: Fastest way to copy? → System.arraycopy() (native method)

Q9: How to sort descending? → Use Integer[] with Arrays.sort(arr, Collections.reverseOrder())

Q10: Null vs empty array? → Null has no object; empty (new int[0]) is a valid object with length 0

Exam Focus

Revise definitions, diagrams, examples, and short-answer points for Array Interview Questions.

Interview Use

Prepare one clear explanation, one practical example, and one common mistake for this Java Master Course topic.

Search Terms

java-master-course, java master course, java, master, course, fundamentals, arrays, interview

Continue learning this concept

PreviousArray Programs — Fundamentals NextJagged Array in Java

Section 1: Conceptual Questions

Q1: What is an array in Java?

Q2: Where are arrays stored in memory?

Q3: What is the difference between length, length(), and size()?

Q4: What are default values of array elements?

Q5: Can we change the size of an array after creation?

Q6: What is the difference between int[] a and int a[]?

Q7: Can we create an array of size 0?

Q8: What is an anonymous array in Java?

Q9: Explain array cloning in Java.

Q10: What is ArrayStoreException?

Section 2: Coding Questions with Solutions

Q11: Write a program to find the third largest element without sorting.

Q12: Find the element that appears odd number of times.

Q13: Separate even and odd numbers in an array.

Q14: Find the subarray with given sum (non-negative numbers).

Section 3: Predict the Output Questions

Q15: What is the output?

Q16: What is the output?

Q17: What is the output?

Q18: What is the output?

Section 4: Tricky and Advanced Questions

Q19: What happens with negative array size?

Q20: Can an array hold different types?

Q21: Maximum array size in Java?

Q22: How to convert array to ArrayList and vice versa?

Q23: Why does Arrays.asList() return a fixed-size list?

Q24: Explain covariance in arrays.

Q25: What is the time and space complexity of common array operations?

Common Mistakes

Best Practices

Interview Questions (Quick-Fire Round)

Continue learning this concept

Section 1: Conceptual Questions

Q1: What is an array in Java?

Q2: Where are arrays stored in memory?

Q3: What is the difference between length, length(), and size()?

Q4: What are default values of array elements?

Q5: Can we change the size of an array after creation?

Q6: What is the difference between int[] a and int a[]?

Q7: Can we create an array of size 0?

Q8: What is an anonymous array in Java?

Q9: Explain array cloning in Java.

Q10: What is ArrayStoreException?

Section 2: Coding Questions with Solutions

Q11: Write a program to find the third largest element without sorting.

Q12: Find the element that appears odd number of times.

Q13: Separate even and odd numbers in an array.

Q14: Find the subarray with given sum (non-negative numbers).

Section 3: Predict the Output Questions

Q15: What is the output?

Q16: What is the output?

Q17: What is the output?

Q18: What is the output?

Section 4: Tricky and Advanced Questions

Q19: What happens with negative array size?

Q20: Can an array hold different types?

Q21: Maximum array size in Java?

Q22: How to convert array to ArrayList and vice versa?

Q23: Why does Arrays.asList() return a fixed-size list?

Q24: Explain covariance in arrays.

Q25: What is the time and space complexity of common array operations?

Common Mistakes

Best Practices

Interview Questions (Quick-Fire Round)

Continue learning this concept

Q3: What is the difference between `length`, `length()`, and `size()`?

Q6: What is the difference between `int[] a` and `int a[]`?

Q23: Why does `Arrays.asList()` return a fixed-size list?

Q3: What is the difference between `length`, `length()`, and `size()`?

Q6: What is the difference between `int[] a` and `int a[]`?

Q23: Why does `Arrays.asList()` return a fixed-size list?