Array Programs in Java — Java Technical Interview Questions & Answers

Array Programs in Java

Array Programs in Java

  • Array Programs is about Java arrays. An array is a fixed-size row of the same type. Index from 0. Length is a.length (a field, not a method). Last valid index is length - 1.
  • Create Array Programs: int[] a = new int[5]; or int[] a = {10, 20, 30};. A 2D array is an array of arrays: int[][] m = {{1,2},{3,4}}; m[1][0] is 3. Jagged means rows can have different lengths.
  • Array Programs size cannot grow. If you need grow/shrink, use ArrayList. Out of range → ArrayIndexOutOfBoundsException.
  • Let's take this on the board with one tiny Main class — no extra files. Array Programs in Java — prints length 3, middle value 20, then all values. Start from main, go line by line, and stop at each print. That output is the proof for Array Programs.
  index →  0    1    2
  array → [10,  20,  30]
           ↑         ↑
         first   length-1

Technical Interview Tip: Contrast array vs ArrayList in one line.

Code Examples for Array Programs in Java

Example

// Array demo
public class Main {
  public static void main(String[] args) {
    int[] nums = {10, 20, 30};
    System.out.println(nums.length);
    System.out.println(nums[1]);
    for (int n : nums) System.out.print(n + " ");
  }
}

Array Programs in Java — prints length 3, middle value 20, then all values.

How to Explain Array Programs in Java to an Interviewer

What is Array Programs?

Array Programs — array = fixed-size, same type, index from 0. Array Programs — a.length is a field. Last index = length - 1. Array Programs — 2D = array of arrays. Jagged = rows of different length.

Why do we use Array Programs in Java?

Makes the program clearer or safer Array Programs — array = fixed-size, same type, index from 0.

Write one small example of Array Programs.

Show syntax Say what prints

What mistake do beginners make with Array Programs?

Only the name, no example Array Programs — a[a.length] crashes. Size cannot grow — use ArrayList.

Where is Array Programs used in a real program?

Day-to-day Java code