Practice Test GeeksAP CSA - Advanced Placement Computer Science A Practice Test
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String Manipulation and 2D Arrays Flashcards

6 cards from real AP CSA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. What does `str.toUpperCase()` do?

    Answer: Returns a new String with all characters converted to uppercase

    toUpperCase() returns a new String with all alphabetic characters converted to uppercase; Strings in Java are immutable so the original is unchanged.

  2. How do you access the element in row 2, column 3 of a 2D array called `grid`?

    Answer: grid[2][3]

    2D array elements are accessed with [row][column] syntax; grid[2][3] accesses row 2 (third row), column 3 (fourth column).

  3. What nested loop structure traverses all elements of a 2D array `int[][] m` with r rows and c columns?

    Answer: for(int i=0;i<m.length;i++) for(int j=0;j<m[i].length;j++)

    The outer loop uses m.length for rows and the inner loop uses m[i].length for columns, correctly visiting every element.

  4. What does `str.substring(3)` return for `str = "JavaCode"`?

    Answer: "aCode"

    substring(3) returns all characters from index 3 to the end; J(0),a(1),v(2),a(3)Code → "aCode".

  5. What is the result of `"5" + 3 + 2` in Java?

    Answer: "532"

    Java evaluates left to right: "5"+3 is String concatenation giving "53", then "53"+2 gives "532" — not arithmetic.

  6. How do you fill an entire 2D array `grid` of size n×m with the value 0?

    Answer: Declare it as `int[][] grid = new int[n][m]` (auto-initialized to 0)

    Java automatically initializes int array elements to 0, so `new int[n][m]` creates a 2D array already filled with zeros.