Java print on based position

Doing homework and I'm stuck.

Let's say I have an array colors:

["blue", "orange", "green", "black", "red" ]

and these colors occur in a text. When the color occurs there is another array that stores the line number in another array (position array).

[17,4,5,8,8]

Now I want to print by ascending line occurrence so the output would be:

orange
green
black
red
blue

I use the Arrays.sort() to sort the position array. I believe that this should be d开发者_JAVA百科one using position.

For example, for printing orange, there is a relation of the sorted array with the position of the color on the array colors.

Can you point me in some direction?

As I started to learn java this as to be done the simplest way possible.

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1. You need to associate the indices with each other. I would recommend you to do it in a class (maybe a Pair class with the attributes String color and int line).

   class Pair {
       public String color;
       public int line;
       public Pair(String color, int line) {
           this.color = color;
           this.line  = line;
       }
   }
   

2. Build up an array (or List<Pair>) of the paired objects.

   String[] colors = new String[] {"blue", "orange", "green", "black", "red"};
   int[] lines     = new int[]    {    17,        4,       5,       8,     8};
   
   List<Pair> pairs = new LinkedList<Pair>();
   for (int i = 0; i < colors.length; i++)
       pairs.add(new Pair(colors[i], lines[i]));
   

3. Sort the array of Pairs with an Comparator using Arrays.sort (or Collection.sort) method depending on your line attribute.

   Collections.sort(pairs, new Comparator<Pair>() {
       public int compare(Pair p1, Pair p2) {
           return Integer.valueOf(p2.line).compareTo(p1.line);
       }
   });
   

   Another option would be to implement Comparable<Pair> in Pair.

4. Print the array using a loop

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I would probably use a SortedMap.

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This works for me and outputs:

orange - 4
green - 5
black - 8
red - 8
blue - 17

Exmaple code:

public class Test
{  
    public String color;
    public int line;

    Test(String color, int line) {
        this.color = color;
        this.line = line;
    }

    public static void main(String[] args) 
    {
        String[] colors = new String[] { "blue", "orange", "green", "black", "red" };
        int[] lineNumber = new int[] { 17,4,5,8,8 };

        LinkedList<Test> out = new LinkedList<Test>();

        // add first element
        out.add(new Test(colors[0], lineNumber[0]));

        Loop: for(int i = 1; i < colors.length; i++) {
            for(int j = 0; j < out.size(); j++) {
                if(lineNumber[i] < out.get(j).line) {
                    out.add(j, new Test(colors[i], lineNumber[i]));
                    continue Loop;
                }
            }

            out.addLast(new Test(colors[i], lineNumber[i]));
        }

        for(Test t : out) {
            System.out.println(t.color + " - "+t.line);         
        }
    }      
}

---

You can use a HashMap. So for every color you have a Key by the color name and for that Key you will need some sort of List of integers.

So what I would recommend is..

Map<String color, List<Integer> location> hashMap = new HashMap<String Color, List<Integer> location>();

if you want to add a position you do.

hashMap.get("orange").add(1);

which means you want to get the list of orange and add the value 1 to that list.

So if you want to iterate that list you would do..

List<Integer> location = hashMap.get("orange"); returning the whole orange list

and then

for(Integer int : location)
{
   //Do whatever
}