IfRequiresElse

DRAFT

Observed

Correction

Here is what's right.

In Java it is perfectly legal to have if statements without else.

However, the conditional operator (c ? et : ef) does require expressions for both cases (et and ef). This is because the conditional operator is an expression, and thus it must produce a value no matter whether the condition is true. An if statement does not have that requirement, because it is a statement, and thus it does not produce any value.

Example

Here we see an occurrence where the student added an else containing an assignment that changes nothing:

int count(int[] values, int value) {
  for (int v : values) {
    if (v==value) {
      count = count + 1;
    } else { // else branch is not necessary
      count = count;
    }
  }
}

This probably comes from learning to program in a pure functional language, where everything is an expression.