Given: public class Test { public static void main(String[] args) { String[][] chs = new String[2][]; chs[0] = new String[2]; chs[1] = new String[5]; int i = 97; for (int a = 0; a < chs.length; a++)…

The correct answer is A. 97 98 99 100 null null null. Option A is correct because the inner loop uses chs.length (which is 2, the number of rows) instead of chs[a].length (the number of columns per row). This means the fill loop only writes to indices 0 and 1 of chs[1], leaving its remaining three elements as null. When the print…

Creating and Using Arrays

Question

Given:
public class Test {
public static void main(String[] args) {
String[][] chs = new String[2][];
chs[0] = new String[2];
chs[1] = new String[5];
int i = 97;
for (int a = 0; a < chs.length; a++) {
for (int b = 0; b < chs.length; b++) {
chs[a][b] = "" + i;
i++;
}
}
for (String[] ca : chs) {
for (String c : ca) {
System.out.print(c + " ");
}
System.out.println();
}
}
}
What is the result?

Options

A97 98 99 100 null null null
B97 98 99 100 101 102 103
CCompilation rails.
DA NullPointerException is thrown at runtime.
EAn ArrayIndexOutOfBoundsException is thrown at runtime.

How the community answered

(29 responses)

A
69% (20)
B
3% (1)
C
3% (1)
D
10% (3)
E
14% (4)

Explanation

Option A is correct because the inner loop uses chs.length (which is 2, the number of rows) instead of chs[a].length (the number of columns per row). This means the fill loop only writes to indices 0 and 1 of chs[1], leaving its remaining three elements as null. When the print loop iterates over all five elements of chs[1], Java's string concatenation (c + " ") silently converts null references to the literal string "null", producing 99 100 null null null.

B is wrong because it assumes the inner loop runs up to chs[a].length (5 for row 1), but it runs up to chs.length (2). C is wrong because the code compiles without error - jagged arrays and the loop structure are both valid Java. D is wrong because string concatenation ("" + null) never throws a NullPointerException; it produces "null". E is wrong because the fill loop never exceeds the bounds of either row - chs[0] has 2 slots and chs[1] has 5, and b only reaches 1.

Memory tip: When you see a nested loop over a 2D array, always check which length the inner loop uses - array.length gives row count, while array[i].length gives column count for that row. A mismatch is a classic exam trap for jagged arrays.

Topics

#jagged arrays#nested loops#array initialization#null references

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