Issue with comparator

Question

Hello All,
I am having a warning issue with my code. I am trying top implement the comparator into my code. Here is the warning..
EarthquakeDataSet.java:88: warning: [unchecked] unchecked call to compare(T,T) as a member of the raw type java.util.Comparator
               if (c.compare(array[low], array[start_high]) == 1)
The appropriate code line is:
if (c.compare(array[low], array[start_high]) == 1) Basically I have Class A, Class B and private static Class C (inner class to B). I have mergesort in A, so in B i have a public method that returns an object instance of C.
A: import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.Comparator;
import javax.swing.JOptionPane;
public class EarthquakeDataSet
     private int nNumRecordsProcessed; // tracks number of records actually stored in array container
     private EarthquakeRecord[] reqrCollection; // reference to array which will be allocated when processing the file
     public EarthquakeDataSet() {
     public long ProcessFile(String sFileName) throws Exception {
          Scanner scanInput = null;
          // use a try-block when opening the file to guard against file-not-found errors
          try {
               scanInput = new Scanner(new File(sFileName));
          } catch (FileNotFoundException e) {
               throw new Exception("Error opening file:" + sFileName);
          int nMaxNumRecords = Integer.parseInt(JOptionPane.showInputDialog("Maximum Number of Records: "));
          nNumRecordsProcessed = 0; // nNumRecordsProcessed may be less then nMaxNumRecords if the array is larger than needed
          long lStartTime = System.currentTimeMillis();
          reqrCollection = new EarthquakeRecord[nMaxNumRecords];
          try {
               while (nNumRecordsProcessed < nMaxNumRecords && scanInput.hasNext()) {
                    String sRawRecord = scanInput.nextLine();
                    reqrCollection[nNumRecordsProcessed] = new EarthquakeRecord(sRawRecord);
                    //System.out.println("test " + reqrCollection[nNumRecordsProcessed].toString() +"\n");
                    nNumRecordsProcessed++;
          } catch (Exception e) {
               throw new Exception("Input failure at record: " + nNumRecordsProcessed);
          //Comparator c; 
          //EarthquakeRecord.CreateDepthObject();
          Comparator c = EarthquakeRecord.CreateDepthObject();
          mergeSort_srt(reqrCollection, 0, 50, c);
          for(int j = 0; j < 50; j++)
               System.out.println("test11 " + reqrCollection[j].toString());
          return System.currentTimeMillis() - lStartTime; // calculate the elapse time
     public String toString() {
          return "Number of Records: " + nNumRecordsProcessed;
     public void mergeSort_srt(EarthquakeRecord array[],int lo, int n, Comparator c)
              int low = lo;
              int high = n;
              if (low >= high)
                     return;
          c = EarthquakeRecord.CreateDepthObject();
              int middle = (low + high) / 2;
              mergeSort_srt(array, low, middle, c);
             mergeSort_srt(array, middle + 1, high, c);
              int end_low = middle;
              int start_high = middle + 1;
          System.out.println(c.toString());
              while ((lo <= end_low) && (start_high <= high))
                     if (c.compare(array[low], array[start_high]) == 1)
                       low++;
               else
                       EarthquakeRecord Temp = array[start_high];
                       for (int k = start_high- 1; k >= low; k--)
                            array[k+1] = array[k];
                    array[low] = Temp;
                          low++;
                          end_low++;
                          start_high++;
          reqrCollection = array;          
}B has following method...
public static CompareDepth CreateDepthObject()
          CompareDepth cd2 = new CompareDepth();
          return cd2;
     }and C private static class CompareDepth implements Comparator <EarthquakeRecord>
          public int compare(EarthquakeRecord erq1, EarthquakeRecord erq2)
               if(erq1.getDepth() < erq2.getDepth())
                    return 1;
               else if(erq1.getEpicentre() > erq2.getEpicentre())
                    return -1;
               else return 0;
     }I know I have a problem setting and passing the reference to the comparator that I want. Ne ideas ??

Answer 1

tanmay.kansara wrote:
hey
here is my main
public class EarthquakeTest {
     public static void main(String[] args) {
          EarthquakeDataSet eqds = new EarthquakeDataSet(); // create object that will manage the collection of EarthquakeRecord objects
          try {
               String sFileName = JOptionPane.showInputDialog("Filename: "); // prompt user for file name
               long lElapseTime = eqds.ProcessFile(sFileName);// open file and parse all data into EarthquakeRecord objects
               System.out.printf("File Processing: Elapsed time: %f \n", ((float)lElapseTime)/1000.0);
          } catch (Exception e) {
               System.out.println("File not found.");
}I do have two pop up boxes that pop up, first one for Filename and second one for number of Entries to sort...
thanks
tanmayRighto... I think I can post my main method without being accused of "spoon feeding" you...
[again, this code is not compiled, and obviously not tested]
public class EarthquakeTest
  private static final long NANOS = 1000000000L; // 10^9
  public static void main(String[] args) {
    try {
      String filename = JOptionPane.showInputDialog("Filename: ");
      if (filename==null) return; // user pressed cancel.
      long start = System.nanoTime();
      EarthquakeManager manager = new EarthquakeManager();
      manager.loadFile(filename);
      manager.sort(new EarthquakeManager.MagnitudeComparator());
      manager.print(System.out);
      long stop = System.nanoTime();
      System.err.println("took "+((stop-start)/NANOS));
    } catch (Exception e) {
      e.printStackTrace();
}The main method says what is happening, but not how... We get a manager, load a user-specified file into the list of quakes, sort, and then print-oput the list... and we're also saying how long the load and sort process took. All good.
Cheers. Keith.