重複しない乱数配列(Java版/コレクション活用?版) ref: http://qiita.com/tsuyoshi_cho/items/2c10819b9f667e41dfe2

Ideone

import java.util.HashSet;
import java.util.ArrayList;
import java.util.Random;

class MakeRandomArray {
    public ArrayList<Integer> makeRandomArray(ArrayList<Integer> array, Random rand, int arraySize, int randMax, int randMin){
    HashSet<Integer> set = new HashSet<>(arraySize);
        for(int i = 1; i <= arraySize; i++){
            set.add(random(rand, randMax, randMin));
        }
        while(set.size() != arraySize){
            set.add(random(rand, randMax, randMin));
        }
        array.addAll(set);
        return array;
    }
    private int random(Random rand, int max,int min){
        if(max < min) return rand.nextInt(min - max) + max;
        else return rand.nextInt(max - min) + min;
    }
}

class Ideone{
    public static void main(String[] args){
        MakeRandomArray mkRandArr = new MakeRandomArray();
        ArrayList<Integer> arr = mkRandArr.makeRandomArray(new ArrayList<Integer>(), new Random(), 10, 100, 1);
        for(int x = 0; x <= 9; x++) System.out.println(arr.get(x));

    }
}

Ideone.java

import java.util.*;
import java.util.stream.*;
import java.lang.Math;

class MakeRandomArray {
    public List<Integer> makeRandomArray(Random rand, int arraySize, int randMax, int randMin){
        List<Integer> array = rand.ints(Math.min(randMin,randMax),Math.max(randMin,randMax))
                .distinct()
                .limit(arraySize)
                .boxed()
                .collect(Collectors.toList());

        return array;
    }
}

class Ideone{
    public static void main(String[] args){
        MakeRandomArray mkRandArr = new MakeRandomArray();
        List<Integer> arr = mkRandArr.makeRandomArray(new Random(), 10, 100, 1);
        for(int x = 0; x <= 9; x++) System.out.println(arr.get(x));
     }
}