How to Search and Array for multiple occurrences of a value

Question

Hi,
I am trying to search an array of doubles for a number and report the index location(s) of a number. I.e. -allow for repetition. Search and report all index[i] where the number is contained in the array. For example I have
double[] myInputArray = new double[5];
double[] myInputArray = { 1, 2, 3, 3, 5 }I know how to search through the array ONCE and return the first occurrence of a number:
public double GetIndexOf(double Number) {
    for (int i=0; i<myInputArray.length; i++) {
         if (myInputArray[i] == Number){
              return(i);
    return(-1);
  }How do I expand this code to report multiple index[i] locations if the number reoccurs in the array like the number 3 does in my example array above?

Answer 1

The way the Java libraries do this type of operation (String.indexOf(), etc) is to specify the starting index along with what you want to find.
Changing your example slightly (notice how I fixed your naming and more importantly, your return type):
public int indexOf(double num) {
   return indexOf(num, 0);
public int indexOf(double num, int fromIndex) {
    for (int i=fromIndex; i<myInputArray.length; i++) {
         if (myInputArray[i] == num){
              return(i);
    return(-1);
//usage to get all indices:
for ( int index = -1; (index = indexOf(num, index+1)) != -1; ) {
   System.out.println(index);
}Note that due to how floating point numbers work, you may find doing this on doubles (or any other operation that uses == with double arguments) to give you unexpected results.