There is a bug in the sortArray method: one particular kind of input will cause a runtime error. In the box provided below, edit sortArray so that it behaves properly on these inputs.
public void sortArray () {
int beginP = 0;
int endP = myArray.length-1;
while(beginP<endP){
if((myArray[beginP]!=BLUE) && (myArray[endP]!=GREEN)){
swap(beginP, endP);
}
while((beginP < myArray.length) && (myArray[beginP]==BLUE)){
beginP++;
}
while(myArray[endP]==GREEN){
endP--;
}
}
Hint:
Look carefully at the nested while loop in the sortArray method body that increments the beginP variable. Now look at the corresponding loop that decrements the endP variable. How are the loop termination conditions different? Use this difference to guess at a string that will cause a runtime error.
The hint gives the whole game away!
Compare:
while((beginP < myArray.length) && (myArray[beginP]==BLUE))
with
while(myArray[endP]==GREEN){
What happens if GREEN is at the end of the array?
while(myArray[endP]==GREEN){
needs to be if rather than while.
int beginP = 0;
int endP = myArray.length-1;
while(beginP<endP){
if((myArray[beginP]!=BLUE) && (myArray[endP]!=GREEN)){
swap(beginP, endP);
}
while((beginP < myArray.length) && (myArray[beginP]==BLUE)){
beginP++;
}
while(myArray[endP]==GREEN){
endP-- = "";
}
}
To fix the bug in the sortArray method, we need to modify the loop termination conditions for both the "beginP" and "endP" variables.
Currently, the loop that increments the "beginP" variable terminates only when "beginP" is less than the length of the "myArray" array, and the element at the current "beginP" index is not equal to BLUE.
The loop that decrements the "endP" variable terminates only when the element at the current "endP" index is equal to GREEN.
To cause a runtime error, we need to provide an input that causes both of these loops to continue indefinitely. From the given hint, the difference in the loop termination conditions suggests that there may be an issue with an input that consists of only GREEN elements or only BLUE elements.
To fix this bug, we can modify the nested while loop condition for the increment of "beginP" to include the termination condition of "endP" being greater than or equal to "beginP". Similarly, we can modify the nested while loop condition for the decrement of "endP" to include the termination condition of "endP" being greater than "beginP".
Here's the modified sortArray method with the fix:
public void sortArray() {
int beginP = 0;
int endP = myArray.length - 1;
while (beginP < endP) {
if ((myArray[beginP] != BLUE) && (myArray[endP] != GREEN)) {
swap(beginP, endP);
}
while ((beginP < myArray.length) && (myArray[beginP] == BLUE) && (endP >= beginP)) {
beginP++;
}
while ((myArray[endP] == GREEN) && (endP > beginP)) {
endP--;
}
}
}
By including the additional termination conditions in the nested while loops, we ensure that the loops will eventually terminate even if the input contains only GREEN or BLUE elements.