To answer this question, we need to analyze the given code step by step:
- The code declares a class
Dims and defines a main method.
- Inside the
main method:
- Line 3 initializes a 2D array
a with two rows and two columns.
- Line 4 assigns the second row of array
a to a 1D array b.
- Line 5 assigns array
a to an Object reference o1.
- Line 6 attempts to cast
o1 to a 2D array a2 (which is the original type of a).
- Line 7 attempts to cast
o1 to a 1D array b2 (which is the original type of b).
- Line 8 prints the value at index 1 of array
b.
- The code does not contain any compilation errors.
Now let's go through each option to determine the correct result:
Option A) 2 - This is not the correct result because the value at index 1 of array b is 4, not 2.
Option B) 4 - This is not the correct result because the value at index 1 of array b is 4, not 2.
Option C) An exception is thrown at runtime - This is the correct result. The code attempts to cast o1 to a 1D array b2 on line 7, but o1 refers to a 2D array a and cannot be cast to a 1D array. This will result in a ClassCastException being thrown at runtime.
Option D) Compilation fails due to an error on line 4 - This is not the correct result. Line 4 does not have any compilation errors. It successfully assigns the second row of array a to array b.
Option E) Compilation fails due to an error on line 5 - This is not the correct result. Line 5 does not have any compilation errors. It successfully assigns array a to the Object reference o1.
Option F) Compilation fails due to an error on line 6 - This is not the correct result. Line 6 does not have any compilation errors. It successfully casts o1 to a 2D array a2.
Therefore, the correct answer is C. An exception is thrown at runtime.