Eliminating Last Comma & Space [duplicate]

Answer 1

check if i has reached the last iteration.

for (i = 0; i < NUM_VALS; i++) {
        if (i == (NUM_VALS - 1))
            System.out.print(hourlyTemp[i]);
        else
            System.out.print(hourlyTemp[i] + ", ");
    }

Answer 2

Check if the last iteration is reached. If not print the comma, otherwise don't.

Replace :

for (i = 0; i < NUM_VALS; i++) {
     System.out.print(hourlyTemp[i] + ", ");
}

With:

for (i = 0; i < NUM_VALS; i++) {
     if (i == (NUM_VALS - 1)) System.out.print(hourlyTemp[i]);
     else System.out.print(hourlyTemp[i] + ", ");
}

Answer 3

As an example, you can put a conditional and just print a blank space once you reach the end.

for(int i=0; i<10; i++) {
    System.out.print(i + (i < 10-1 ? ", " : ""));
}

Answer 4

Split up the value printing and the comma-space printing into two separate statements, and don't print the comma-space for the last value:

System.out.print(hourlyTemp[i]);
if (i + 1 < NUM_VALS) {
  System.out.print(", ");
}

Alternatively, print the first value outside the loop, then print the comma-space first inside the loop:

System.out.print(hourlyTemp[0]);
for (int i = 1; i < NUM_VALS; ++i) {
  System.out.print(", " + hourlyTemp[i]);
}

Answer 5

Generally you don't know number of values to print up-front (but in your case it's 4). So it is easier to print separator before instead of after. No ifs:

String sep="";
for (i = 0; i < NUM_VALS; i++) {
     System.out.print(sep + hourlyTemp[i]);
     sep=", ";
  }

Trick is - first time there is nothing to separate hence separator is empty, later - ", ";

Fits into register, saves branch predictor's work. Calculating if (i == last_value) is not 0 cost as well.

Answer 6

String delimiter = ", ";

The first way is using java.util.StringJoiner. Additionally, you may specify a prefix and suffix of a result string (for example, (delimiter, "[", "]")).

StringJoiner joiner = new StringJoiner(delimiter);
for (int i : hourlyTemp) joiner.add(Integer.toString(i));
System.out.println(joiner.toString());

The second way is using Stream API.

Arrays.stream(hourlyTemp)
            .map(i -> i.toString())
            .collect(Collectors.joining(delimiter));

Or the most boring way:

for (i = 0; i < NUM_VALS;) 
    System.out.print(hourlyTemp[i] + (i++ != (NUM_VALS - 1) ? delimiter : ""));