Introduction to Using Data Sets - AP Computer Science A
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What keyword is used to create an instance of an array?
What keyword is used to create an instance of an array?
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new. Required keyword for dynamic memory allocation of array objects.
new. Required keyword for dynamic memory allocation of array objects.
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Identify the index of the first element in an array.
Identify the index of the first element in an array.
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- Java uses zero-based indexing for all arrays.
- Java uses zero-based indexing for all arrays.
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State the syntax to access the third element of an array named 'arr'.
State the syntax to access the third element of an array named 'arr'.
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arr[2]. Uses zero-based indexing, so index 2 represents the third element.
arr[2]. Uses zero-based indexing, so index 2 represents the third element.
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State the purpose of the 'System.arraycopy()' function.
State the purpose of the 'System.arraycopy()' function.
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Copies elements from one array to another. System method for efficient bulk array element transfer.
Copies elements from one array to another. System method for efficient bulk array element transfer.
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What is a common use case for 2D arrays?
What is a common use case for 2D arrays?
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Representing matrices or grids. Ideal for tabular data like game boards or spreadsheets.
Representing matrices or grids. Ideal for tabular data like game boards or spreadsheets.
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How do you reverse an array 'arr' in Java?
How do you reverse an array 'arr' in Java?
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Use a loop to swap elements or Collections.reverse(Arrays.asList(arr));. Multiple approaches exist since arrays lack built-in reverse method.
Use a loop to swap elements or Collections.reverse(Arrays.asList(arr));. Multiple approaches exist since arrays lack built-in reverse method.
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How do you declare a String array with specific values?
How do you declare a String array with specific values?
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String[] array = {"value1", "value2"};. Array literal syntax works for String objects like other types.
String[] array = {"value1", "value2"};. Array literal syntax works for String objects like other types.
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Identify the error: int[] arr = new int[3]; arr[3] = 10;
Identify the error: int[] arr = new int[3]; arr[3] = 10;
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Access beyond bounds; valid indices are 0 to 2. Index 3 exceeds bounds since valid indices are 0, 1, 2.
Access beyond bounds; valid indices are 0 to 2. Index 3 exceeds bounds since valid indices are 0, 1, 2.
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Which method converts an array to a list?
Which method converts an array to a list?
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Arrays.asList(array). Returns fixed-size list backed by the original array.
Arrays.asList(array). Returns fixed-size list backed by the original array.
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How do you create a reference to an existing array 'arr'?
How do you create a reference to an existing array 'arr'?
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int[] newRef = arr;. Creates alias pointing to same memory location, not a copy.
int[] newRef = arr;. Creates alias pointing to same memory location, not a copy.
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State the method to fill an array with a specific value.
State the method to fill an array with a specific value.
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Arrays.fill(array, value);. Efficiently sets all array elements to the specified value.
Arrays.fill(array, value);. Efficiently sets all array elements to the specified value.
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Which data type can an array hold?
Which data type can an array hold?
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Arrays can hold any primitive or object type. Supports primitives (int, char) and reference types (String, Object).
Arrays can hold any primitive or object type. Supports primitives (int, char) and reference types (String, Object).
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What is the difference between an array and an ArrayList?
What is the difference between an array and an ArrayList?
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ArrayList can dynamically resize; arrays have fixed size. ArrayList grows automatically while arrays have fixed capacity.
ArrayList can dynamically resize; arrays have fixed size. ArrayList grows automatically while arrays have fixed capacity.
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How do you copy an array 'arr' into a new array 'copy'?
How do you copy an array 'arr' into a new array 'copy'?
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int[] copy = Arrays.copyOf(arr, arr.length);. Creates a shallow copy with the same length as original.
int[] copy = Arrays.copyOf(arr, arr.length);. Creates a shallow copy with the same length as original.
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Identify the output: int[] arr = {10, 20}; System.out.println(arr[1]);
Identify the output: int[] arr = {10, 20}; System.out.println(arr[1]);
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- Accesses the second element (index 1) which contains value 20.
- Accesses the second element (index 1) which contains value 20.
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What is an ArrayIndexOutOfBoundsException?
What is an ArrayIndexOutOfBoundsException?
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An error when accessing an index outside the array's bounds. Runtime exception thrown when index is negative or >= length.
An error when accessing an index outside the array's bounds. Runtime exception thrown when index is negative or >= length.
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State the purpose of the 'Arrays.toString()' method.
State the purpose of the 'Arrays.toString()' method.
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Converts array to a readable string format. Formats array contents as [element1, element2, ...] for debugging.
Converts array to a readable string format. Formats array contents as [element1, element2, ...] for debugging.
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How do you iterate over an array 'arr' using a for-each loop?
How do you iterate over an array 'arr' using a for-each loop?
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for (int element : arr) { }. Enhanced for loop syntax that iterates without index management.
for (int element : arr) { }. Enhanced for loop syntax that iterates without index management.
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Identify the error: int[] arr = new int[5]{1, 2, 3, 4, 5};
Identify the error: int[] arr = new int[5]{1, 2, 3, 4, 5};
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Remove size: int[] arr = {1, 2, 3, 4, 5};. Cannot specify size when using array literal initialization syntax.
Remove size: int[] arr = {1, 2, 3, 4, 5};. Cannot specify size when using array literal initialization syntax.
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What is the syntax to declare a char array in Java?
What is the syntax to declare a char array in Java?
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char[] array = new char[size];. Character array declaration follows same pattern as other types.
char[] array = new char[size];. Character array declaration follows same pattern as other types.
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How do you find the maximum value in an integer array 'arr'?
How do you find the maximum value in an integer array 'arr'?
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Use a loop or Arrays.stream(arr).max().getAsInt();. Manual loop or stream API provides maximum value efficiently.
Use a loop or Arrays.stream(arr).max().getAsInt();. Manual loop or stream API provides maximum value efficiently.
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What is the primary advantage of using arrays?
What is the primary advantage of using arrays?
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Efficient access and storage of elements of the same type. Constant-time access and contiguous memory allocation improve performance.
Efficient access and storage of elements of the same type. Constant-time access and contiguous memory allocation improve performance.
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How do you access the element at row 2, column 3 in a 2D array 'array'?
How do you access the element at row 2, column 3 in a 2D array 'array'?
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array[1][2]. First index is row, second index is column in 2D arrays.
array[1][2]. First index is row, second index is column in 2D arrays.
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What does 'array.length' return for a 2D array?
What does 'array.length' return for a 2D array?
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The number of rows. First dimension represents rows; use array[i].length for columns.
The number of rows. First dimension represents rows; use array[i].length for columns.
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What method is used to sort an array in Java?
What method is used to sort an array in Java?
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Arrays.sort(array);. Utility method that sorts elements in ascending order using quicksort.
Arrays.sort(array);. Utility method that sorts elements in ascending order using quicksort.
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How do you initialize an array with values 1, 2, 3 in Java?
How do you initialize an array with values 1, 2, 3 in Java?
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int[] array = {1, 2, 3};. Array literal syntax that creates and initializes in one step.
int[] array = {1, 2, 3};. Array literal syntax that creates and initializes in one step.
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Identify the error: int[] arr = new int[5]{1, 2, 3, 4, 5};
Identify the error: int[] arr = new int[5]{1, 2, 3, 4, 5};
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Remove size: int[] arr = {1, 2, 3, 4, 5};. Cannot specify size when using array literal initialization syntax.
Remove size: int[] arr = {1, 2, 3, 4, 5};. Cannot specify size when using array literal initialization syntax.
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What is an array in Java?
What is an array in Java?
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A data structure to store multiple values of the same type. Allows efficient storage and access to multiple values using indices.
A data structure to store multiple values of the same type. Allows efficient storage and access to multiple values using indices.
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Identify the index of the first element in an array.
Identify the index of the first element in an array.
Tap to reveal answer
- Java uses zero-based indexing for all arrays.
- Java uses zero-based indexing for all arrays.
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Which method converts an array to a list?
Which method converts an array to a list?
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Arrays.asList(array). Returns fixed-size list backed by the original array.
Arrays.asList(array). Returns fixed-size list backed by the original array.
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