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このコードがある場合 ( https://stackoverflow.com/a/4859279/1178781から取得):

import java.util.Comparator;

public class ArrayIndexComparator<T extends Comparable<? super T>> implements
        Comparator<Integer> {
    private final T[] array;

    public ArrayIndexComparator(T[] array) {
        this.array = array;
    }

    public Integer[] createIndexArray() {
        Integer[] indexes = new Integer[array.length];
        for (int i = 0; i < array.length; i++) {
            indexes[i] = i; // Autoboxing
        }
        return indexes;
    }

    @Override
    public int compare(Integer index1, Integer index2) {
        // Autounbox from Integer to int to use as array indexes
        return array[index1].compareTo(array[index2]);
    }
}

プログラムを実行すると、次のようになります。

import java.util.Arrays;
import java.util.Comparator;

public class Launcher {

    /**
     * @param args
     */
    public static void main(String[] args) {
        String[] countries = { "A", "H", "E", "C", "D", "F", "G", "B" };
        ArrayIndexComparator<String> comparator = new ArrayIndexComparator<String>(
                countries);
        Integer[] indexes = comparator.createIndexArray();
        Arrays.sort(indexes, comparator);
        System.out.print("Array:    ");
        System.out.println(Arrays.toString(countries));
        System.out.print("Rankings: ");
        System.out.println(Arrays.toString(indexes));
        System.out.println("");

        final Float[] scores2 = { 2.3f, 0.7f, 1.4f, 1.2f };
        ArrayIndexComparator<Float> comparator2 = new ArrayIndexComparator<Float>(
                scores2);
        indexes = comparator2.createIndexArray();
        Arrays.sort(indexes, comparator2);
        System.out.print("Array:    ");
        System.out.println(Arrays.toString(scores2));
        System.out.print("Rankings: ");
        System.out.println(Arrays.toString(indexes));
        System.out.println("");

        final Integer[] scores3 = { 1, 2, 0, 3 };
        ArrayIndexComparator<Integer> comparator3 = new ArrayIndexComparator<Integer>(
                scores3);
        indexes = comparator3.createIndexArray();
        Arrays.sort(indexes, comparator3);
        System.out.print("Array:    ");
        System.out.println(Arrays.toString(scores3));
        System.out.print("Rankings: ");
        System.out.println(Arrays.toString(indexes));
        System.out.println("");

        final Integer[] scores4 = { 1, 0, 2, 3 };
        ArrayIndexComparator<Integer> comparator4 = new ArrayIndexComparator<Integer>(
                scores4);
        indexes = comparator4.createIndexArray();
        Arrays.sort(indexes, comparator4);
        System.out.print("Array:    ");
        System.out.println(Arrays.toString(scores4));
        System.out.print("Rankings: ");
        System.out.println(Arrays.toString(indexes));
        System.out.println("");

    }

}

出力は次のとおりです。

Array:    [A, H, E, C, D, F, G, B]
Rankings: [0, 7, 3, 4, 2, 5, 6, 1]

Array:    [2.3, 0.7, 1.4, 1.2]
Rankings: [1, 3, 2, 0]

Array:    [1, 2, 0, 3]
Rankings: [2, 0, 1, 3]

Array:    [1, 0, 2, 3]
Rankings: [1, 0, 2, 3]

これにより、配列内のオブジェクトのランキングが正しく表示されるはずだと思いましたが、特定の構成ではそうではありません。何か不足していますか？それとも、これは実際にはランキングを提供するための並べ替えではなく、別の何かですか?

例えば：

Array:    [A, H, E, C, D, F, G, B]
Rankings: [0, 7, 3, 4, 2, 5, 6, 1]
Should be:[0, 7, 4, 2, 3, 5, 6, 1]

Array:    [2.3, 0.7, 1.4, 1.2]
Rankings: [1, 3, 2, 0]
Should be:[3, 0, 2, 1]

Array:    [1, 2, 0, 3]
Rankings: [2, 0, 1, 3]
Should be:[1, 2, 0, 3]    

Array:    [1, 0, 2, 3]
Rankings: [1, 0, 2, 3]
Should be:[1, 0, 2, 3]
4

1 に答える 1

0

重複を考慮する必要がないという事実に基づいて、すべてを次のように変更できます。

public static void main(String[] args) {
    String[] countries = { "A", "H", "E", "C", "D", "F", "G", "B" };
    ArrayComparator<String> comparator = new ArrayComparator<String>(
            countries);
    Integer[] indexes = comparator.createIndexArray();
    System.out.print("Array:     ");
    System.out.println(Arrays.toString(countries));
    System.out.print("Rankings: ");
    System.out.println(Arrays.toString(indexes));
    System.out.println("");

    final Float[] scores2 = { 2.3f, 0.7f, 1.4f, 1.2f };
    ArrayComparator<Float> comparator2 = new ArrayComparator<Float>(
            scores2);
    indexes = comparator2.createIndexArray();
    System.out.print("Array:     ");
    System.out.println(Arrays.toString(scores2));
    System.out.print("Rankings: ");
    System.out.println(Arrays.toString(indexes));
    System.out.println("");

    final Integer[] scores3 = { 1, 2, 0, 3 };
    ArrayComparator<Integer> comparator3 = new ArrayComparator<Integer>(
            scores3);
    indexes = comparator3.createIndexArray();
    System.out.print("Array:     ");
    System.out.println(Arrays.toString(scores3));
    System.out.print("Rankings: ");
    System.out.println(Arrays.toString(indexes));
    System.out.println("");

    final Integer[] scores4 = { 1, 0, 2, 3 };
    ArrayComparator<Integer> comparator4 = new ArrayComparator<Integer>(
            scores4);
    indexes = comparator4.createIndexArray();
    System.out.print("Array:     ");
    System.out.println(Arrays.toString(scores4));
    System.out.print("Rankings: ");
    System.out.println(Arrays.toString(indexes));
    System.out.println("");

}

public class ArrayComparator<T extends Comparable<? super T>>{
    private final T[] array;
    private final SortedMap<T, Integer> sortedArray;

    public ArrayComparator(T[] array){
        this.array = array;
        sortedArray = new TreeMap<T, Integer>();
        for(int i = 0 ; i < array.length ; i ++){
            sortedArray.put(array[i], Integer.valueOf(i));
        }
    }

    public Integer[] createIndexArray(){
        Integer[] indexArray = new Integer[sortedArray.size()];
        int i = 0;
        for(T key : sortedArray.keySet()){
            indexArray[sortedArray.get(key)] = i;
            i++;
        }
        return indexArray;
    }
}

次に実行すると、出力は次のようになります。

Array:     [A, H, E, C, D, F, G, B]
Rankings:  [0, 7, 4, 2, 3, 5, 6, 1]

Array:     [2.3, 0.7, 1.4, 1.2]
Rankings:  [3, 0, 2, 1]

Array:     [1, 2, 0, 3]
Rankings:  [1, 2, 0, 3]

Array:     [1, 0, 2, 3]
Rankings:  [1, 0, 2, 3]

あなたが探していると私は信じています。

于 2013-02-28T20:08:38.893 に答える