Object Oriented Programming Week 10: Arrays
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Questions and Answers

What happens when an argument is passed by value in a method call?

  • The called method cannot modify the argument's data. (correct)
  • The original variable's value is modified directly.
  • Both the original and the copied values are modified.
  • A copy of the argument's value is created for the method. (correct)

    • Which of the following statements is true regarding pass-by-reference?

  • It does not improve performance when passing large data.
  • The called method can access and modify the original variable's value. (correct)
  • The called method works with a separate copy of the argument.
  • Pass-by-reference is always used for primitive data types.

    • What is a characteristic of multidimensional arrays?

  • They can only have two dimensions: rows and columns.
  • They are similar to tables with spots for rows and columns. (correct)
  • They are defined using a single row of values.
  • They cannot contain varying lengths of sub-arrays.

    • In which case can Java allow modification of an object's data when passing it to a method?

    <p>When dealing with reference object types. (B)</p> Signup and view all the answers

    How are two-dimensional arrays declared and initialized in Java?

    <p>Using brackets to group the elements into rows. (A)</p> Signup and view all the answers

    What type of variable can hold only one value at a time?

    <p>Primitive type (B)</p> Signup and view all the answers

    Which keyword is used to create an array in Java?

    <p>new (B)</p> Signup and view all the answers

    What will the expression 'c.length' return?

    <p>The total number of elements in array c (A)</p> Signup and view all the answers

    What does the term 'Pass-By-Reference' imply when passing arrays to methods?

    <p>The method can modify the original array. (A)</p> Signup and view all the answers

    In the expression 'c[a + b] += 2', what will it affect when 'a' is 5 and 'b' is 6?

    <p>It will add 2 to element c[11]. (D)</p> Signup and view all the answers

    Which statement is true regarding the index of an array?

    <p>Index must be a positive integer or integer expression. (D)</p> Signup and view all the answers

    What is the purpose of the finally statement in a try-catch block?

    <p>To guarantee code execution after try-catch regardless of any exception. (D)</p> Signup and view all the answers

    What does 'sum = c + c + c' imply about array c?

    <p>It aggregates the values in all elements of c. (B)</p> Signup and view all the answers

    What is the output when trying to print an array directly in Java?

    <p>A reference to the array object is printed. (C)</p> Signup and view all the answers

    What is the result of modifying an element in an array passed to a method using Pass-By-Value?

    <p>The original array remains unchanged. (A)</p> Signup and view all the answers

    What happens if an exception is thrown in the try block but not caught?

    <p>The program terminates without executing the catch block. (D)</p> Signup and view all the answers

    How do you pass an array to a method in Java?

    <p>Use the array name directly without brackets. (C)</p> Signup and view all the answers

    What type of loop does the enhanced for statement represent in Java?

    <p>A loop designed to iterate through each element of an array. (A)</p> Signup and view all the answers

    In which situation would you see the output 'Something went wrong.'?

    <p>If an exception occurs within the try block. (B)</p> Signup and view all the answers

    Why is it important to avoid stepping outside the array bounds?

    <p>It prevents ArrayIndexOutOfBoundsException. (C)</p> Signup and view all the answers

    What is an advantage of using an enhanced for statement?

    <p>It eliminates the need for a loop counter and reduces errors. (C)</p> Signup and view all the answers

    What is the correct way to declare and create an array of integers in Java?

    <p>int[] c; c = new int[5]; (B)</p> Signup and view all the answers

    Which of the following options correctly initializes two String arrays in a single declaration?

    <p>String[] b, x = new String[]; (B)</p> Signup and view all the answers

    What does the try-catch statement accomplish in Java?

    <p>It allows handling of exceptions that might occur during execution. (B)</p> Signup and view all the answers

    In the context of Java, what is the purpose of the catch statement within a try-catch block?

    <p>To define the block of code that handles exceptions if they occur. (C)</p> Signup and view all the answers

    What will happen if you run the following code: System.out.println(myNumbers); without proper indexing?

    <p>It will raise an exception at runtime. (A)</p> Signup and view all the answers

    How can an exception be defined within a Java program?

    <p>As an indication of a problem during program execution. (D)</p> Signup and view all the answers

    What is a common use of array initializers in Java?

    <p>To directly assign values to an array during creation. (A)</p> Signup and view all the answers

    Which of the following is NOT a valid syntax for initializing an array in Java?

    <p>int nums[] = new int(3); (A)</p> Signup and view all the answers

    Flashcards

    Array Declaration

    Declaring a variable that will hold an array of values of a specific data type. Example: int[] numbers;

    Array Initialization

    Assigning values to the array elements. Example: int[] numbers = {1, 2, 3};

    Array Indexing

    Accessing elements within the array using their position (index). The first element has index 0. Example: numbers[0] = 1;

    Try-Catch

    A programming structure in Java (and other languages) for handling possible errors (exceptions) during program execution.

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    Exception

    An error condition detected during program execution. Example: ArrayIndexOutOfBoundsException

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    Try block

    A section of code in a try-catch statement that is executed first. It includes the code that could produce an error.

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    Catch block

    A section of code in a try-catch statement that is executed if an error occurs in the try block.

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    ArrayIndexOutOfBoundsException

    An exception that occurs when attempting to access an array element using an invalid index.

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    Primitive type variable

    Holds one value of its type. When assigned a new value, the previous one is replaced.

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    Reference type variable

    Stores the memory address of an object. The variable is a pointer to the object's location in memory.

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    Array length

    The total number of elements an array can hold. Access it using the .length property.

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    Modifying Arrays

    Changing the value of an element within an array

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    Pass-by-Value

    A method receives a copy of the variable's value. Changes to the copy don't affect the original variable.

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    Pass-by-Reference

    A method call where the called method can directly access and modify the argument's value in the caller. This avoids copying data and improves performance.

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    How are arguments passed in Java?

    Java always uses pass-by-value. This means a copy of the argument is passed to the called method.

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    What is a multidimensional array?

    An array that represents data in a table form with rows and columns. Example: A two-dimensional array can store data for a spreadsheet.

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    How can you declare a two-dimensional array?

    Use double square brackets: int[][] b = {{1, 2}, {3, 4}}; Each inner array represents a row.

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    Try-Catch Statement

    A Java construct used to handle potential exceptions during program execution.

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    finally statement

    A block of code in a try-catch statement, always executed, regardless of errors, especially closing resources.

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    Enhanced for loop

    A loop in Java used to iterate over the elements of an array or collection, more readable than using indices.

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    Passing Arrays to Methods

    Methods can receive arrays as parameters. The array name, without brackets, is used in the method signature.

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    Array

    An ordered collection of elements of the same data type.

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    Index

    A numerical position used to access elements in an array (starting from zero).

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    Study Notes

    Course Information

    • Course: Object Oriented Programming
    • Institution: Saudi Electronic University
    • Week: 10
    • Topic: Arrays

    Primitive vs. Reference Types

    • Primitive variables hold a single value of the declared type
    • Assigning a new value to a primitive variable replaces the previous one
    • Reference types store memory addresses of objects
    • A reference variable refers to an object, not the object's data itself

    Creating, Initializing, and Modifying Arrays

    • Arrays store multiple data elements of the same type
    • Fixed-length data structures
    • Array size is determined when it’s created
    • Elements are accessed using index numbering, starting from 0

    Exception Handling (Try-Catch Statements)

    • Exceptions indicate errors during program execution
    • Handle potential errors by placing error-prone code within a try block
    • Corresponding catch blocks handle the exception if it occurs

    Enhanced for Statement

    • Iterates through array elements without a counter
    • Prevents the risk of going beyond array boundaries

    Passing Arrays to Methods

    • Specify the array name in the method call
    • Pass-by-value—the method receives a copy of the values in the array; changes to the copy within the method will not affect the original array
    • Pass-by-reference—the method receives a refrence to the data; changes within the method will affect the original array

    Pass-By-Value vs. Pass-By-Reference

    • Pass-by-value: A copy of the parameter is created, changes inside the method don't affect the original data in the calling method.
    • Pass-by-reference: The method receives a reference to the original data, changing the values in the method directly impacts the original values.

    Multidimensional Arrays

    • Arrays with multiple levels of indices (e.g., tables with rows and columns)
    • Declaring a two-dimensional array example b[2][2]

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    Week 10 Arrays PDF

    Description

    This quiz covers key concepts related to arrays in Object Oriented Programming. Explore the differences between primitive and reference types, how to create and modify arrays, and the basics of exception handling with try-catch statements. Test your understanding of enhanced for statements used in array iteration.

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