You'll need to create a new array if you want to add an index.
Try this:
public static void main(String[] args) {
int[] series = new int[0];
int x = 5;
series = addInt(series, x);
//print out the array with commas as delimiters
System.out.print("New series: ");
for (int i = 0; i < series.length; i++){
if (i == series.length - 1){
System.out.println(series[i]);
}
else{
System.out.print(series[i] + ", ");
}
}
}
// here, create a method
public static int[] addInt(int [] series, int newInt){
//create a new array with extra index
int[] newSeries = new int[series.length + 1];
//copy the integers from series to newSeries
for (int i = 0; i < series.length; i++){
newSeries[i] = series[i];
}
//add the new integer to the last index
newSeries[newSeries.length - 1] = newInt;
return newSeries;
}