尝试从 while 循环返回时出现无法访问的语句错误 - Java

Question

static long minDaysToEmpty(long C, long l) {
    long previousFill=C;
    long day=1;
    long currentFill=C;
    while(true){
        currentFill=Math.min(C,(previousFill-(day))+l);
        previousFill=currentFill;
        day++;
        if(day>3){
            return day;
        }
    }
    return day;
}

This code throws a compile time error.

Test.java:15: error: unreachable statement return day;

I don't understand why this statement can't be reached.

On doing the below modification to the original code, the if block is reachable

if(day>3){
  break;
}

But inside the same block return statement is unreachable.

Answer 1

Since the while loop is while (true) and contains no break statements, the only way the loop can exit is by fulfilling this condition, which is already returning from the method

if (day > 3) {
    return day;
}

Therefore the return day at the bottom of the method is not possible to reach.

Just remove that line return day; at the bottom of the method. Provided your logic is correct and day will eventually be greater than 3, you don't need it.

Alternatively, choose a proper condition rather than while (true) , or add a break statement.