按字母顺序选择的2D数组

Question

My assignment asks me to store inputted data in a 2D array and use a selection sort to sort the crimes in alphabetical order. How can I alter the following selection sort:

//selection sort
    for(i = 0; i < criminal.length; i++){
        smallest = i;

        for(j = i; j < criminal.length; j++){
            //compare smallest to current position
            if(criminal[j] < criminal[smallest]){
                smallest = j;
            }

         //swap smallest with position in the array
         temp = criminal[i];
         criminal[i] = criminal[smallest];
         age[smallest] = temp;

        }


    }           
    //output 
    for(i = 0; i < criminal.length; i++){
        System.out.println(criminal[i]);
    }

So that it can accommodate a 2D array that looks like this:

//loop to request to fill array
    for (i = 0; i < criminals.length ; i++) {               
            System.out.print("Enter first and last name of criminal: ");
            criminals[i][0] = br.readLine(); //Criminal Name

            System.out.print("Enter crime committed: ");
            criminals[i][1] = br.readLine(); //Criminal Crime

            System.out.print("Enter year of conviction: ");
            criminals[i][2] = br.readLine(); //Year of conviction
    }

That's it. Any help would be great! I really need to finish this ASAP. Thanks in advance. :)

Answer 1

Depends on what you're sorting on. If you want to sort the criminals based on their name, then every time you have something like criminal[X] in the selection sort algorithm, replace it with criminal[X][0] . Similarly if you want to sort based on year of conviction replace criminal[X] with criminal[X][2] , etc.

One note, if you're sorting on strings don't use < , use the compareTo() method instead.

Answer 2

You are sorting names, and they happen to have two other fields associated with them. When your sort moves stuff around by swapping indices, it should swap the appropriate indices for the entries (the rows) in criminals[][].

Answer 3

Arrays.sort(criminal, new Comparator<String[]>() {
   @Override
   public int compare(String[] o1, String[] o2) {
      return o1[0].compareTo(o2[0]);
   }        
});