Java Data Structure How to - Sort Duplicate Keys with respective values

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Question

We would like to know how to sort Duplicate Keys with respective values.

Answer

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
/*from   ww  w  . jav  a2s.  c o  m*/
class SortByHouseNo implements Comparator<HouseNo> {

  @Override
  public int compare(HouseNo o1, HouseNo o2) {
    Integer first = Integer.valueOf(o1.getHouseno());
    Integer second = Integer.valueOf(o2.getHouseno());

    Integer f1 = Integer.valueOf(o1.getBlockno());
    Integer f2 = Integer.valueOf(o2.getBlockno());

    if (first.compareTo(second) == 0) {
      return f1.compareTo(f2);
    }
    return first.compareTo(second);
  }
}

public class Main {

  public static void main(String[] args) {
    String houseList[] = { "9-11", "9-01", "10-02", "10-01", "2-09", "3-88",
        "9-03", "9-3" };
    HouseNo house = null;
    ArrayList<HouseNo> sortedList = new ArrayList<>();
    for (String string : houseList) {
      String h = string.substring(0, string.indexOf('-'));
      String b = string.substring(string.indexOf('-') + 1);
      house = new HouseNo(h, b);
      sortedList.add(house);
    }

    System.out.println("Before Sorting :: ");
    for (HouseNo houseNo : sortedList) {
      System.out.println(houseNo);
    }

    Collections.sort(sortedList, new SortByHouseNo());
    System.out.println("\n\nAfter Sorting HouseNo :: ");
    for (HouseNo houseNo : sortedList) {
      System.out.println(houseNo);
    }
  }
}

class HouseNo {
  public HouseNo(String house, String block) {
    this.houseno = house;
    this.blockno = block;
  }
  String houseno;
  String blockno;
  public String getHouseno() {
    return houseno;
  }
  public void setHouseno(String houseno) {
    this.houseno = houseno;
  }
  public String getBlockno() {
    return blockno;
  }
  public void setBlockno(String blockno) {
    this.blockno = blockno;
  }
  @Override
  public String toString() {
    return "House -> " + this.getHouseno() + "-" + this.getBlockno();
  }
}

The code above generates the following result.

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