Question 346 of 509
Java Basics and SyntaxmediumMultiple SelectObjective-mapped

1Z0-811 Two-dimensional array declaration Practice Question

This 1Z0-811 practice question tests your understanding of java basics and syntax. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: two-dimensional array declaration. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Which TWO are valid ways to declare and initialize a two-dimensional int array in Java?

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

int[][] arr = new int[2][2];

Option A is correct because `int[][] arr = new int[2][2];` uses the standard syntax for declaring and initializing a two-dimensional int array in Java, where both dimensions are specified at creation time, and all elements default to 0. The first option (null key) is correct because `int[][] arr = {{1,2},{3,4}};` uses an array initializer to declare and initialize the array with specific values in a single statement, which is valid for local variables or fields. Option B is also correct because `int[][] arr = new int[2][4];` declares and initializes a two-dimensional array with dimensions 2 and 4, which is a valid syntax; both dimensions must be positive integers.

Key principle: Two-dimensional array declaration

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • int[][] arr = new int[2][2];

    Why this is correct

    Correct. This creates a 2x2 int array with all elements defaulting to 0.

    Related concept

    Two-dimensional array declaration

  • int[][] arr = new int[2][4];

    Why this is correct

    Correct. This creates a 2x4 int array, a valid declaration and initialization.

    Related concept

    Two-dimensional array declaration

  • int[][] arr = new int[][2];

    Why it's wrong here

    Invalid because the first dimension must be specified when using `new` without an initializer.

  • int[][] arr = new int[2][2]{{1,2},{3,4}};

    Why it's wrong here

    Invalid because `new` and an array initializer cannot be combined in the same statement.

  • int[][] arr = new int[2][];

    Why it's wrong here

    Invalid for the purpose of this question because `new int[2][]` creates a jagged array where the second dimension is not specified, so the rows are null; it is not considered fully initialized as a rectangular array.

  • int[][] arr = {{1,2},{3,4}};

    Why this is correct

    Valid initialization with values.

    Related concept

    Two-dimensional array declaration

Common exam traps

Common exam trap: answer the scenario, not the keyword

Oracle often tests the distinction between valid array initialization syntax and common invalid combinations, such as mixing `new` with an array initializer or omitting the first dimension size without an initializer, which trips up candidates who confuse C-style or other language syntax with Java's rules.

Detailed technical explanation

How to think about this question

In Java, a two-dimensional array is an array of arrays, where each row is a reference to a one-dimensional int array. When using `new int[2][2]`, memory is allocated for a 2x2 contiguous block, while `{{1,2},{3,4}}` uses an array initializer that implicitly creates the array and assigns values at compile time. A subtle behavior is that `new int[2][]` creates a jagged array where each row can have a different length, but the second dimension must be explicitly initialized before use.

KKey Concepts to Remember

  • Two-dimensional array declaration
  • Array initializer
  • Valid `new` syntax

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Two-dimensional array declaration

Real-world example

How this comes up in practice

A practitioner preparing for the 1Z0-811 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Two-dimensional array declaration Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this 1Z0-811 question test?

Java Basics and Syntax — This question tests Java Basics and Syntax — Two-dimensional array declaration.

What is the correct answer to this question?

The correct answer is: int[][] arr = new int[2][2]; — Option A is correct because `int[][] arr = new int[2][2];` uses the standard syntax for declaring and initializing a two-dimensional int array in Java, where both dimensions are specified at creation time, and all elements default to 0. The first option (null key) is correct because `int[][] arr = {{1,2},{3,4}};` uses an array initializer to declare and initialize the array with specific values in a single statement, which is valid for local variables or fields. Option B is also correct because `int[][] arr = new int[2][4];` declares and initializes a two-dimensional array with dimensions 2 and 4, which is a valid syntax; both dimensions must be positive integers.

What should I do if I get this 1Z0-811 question wrong?

Review two-dimensional array declaration, then practise related 1Z0-811 questions on the same topic to reinforce the concept.

What is the key concept behind this question?

Two-dimensional array declaration

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Last reviewed: Jun 30, 2026

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This 1Z0-811 practice question is part of Courseiva's free Oracle certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 1Z0-811 exam.