hashset从数组Java中删除重复项

Question

我目前正在尝试使我的Java程序不打印出重复的法律。 该软件是随机选择的，可打印1至3条法律，但我不希望重复。 我对Java还是很陌生，到目前为止只写了一些程序。 这是我到目前为止编写的最复杂的代码。

现在，我希望该软件在找到重复项之前再次运行随机文件，直到打印件中没有重复项为止。 反正有这样做吗？

/**
    *Seeds is a random number to pick which if statement will be used. 
    * telling the software how many laws to use during its random 
    * generation process
    * 
    */
    Random seeds = new Random(); 
    seed = seeds.nextInt(3) + 1; 

    if (seed == 1){


        /**Beginning of random law selection for universe. Must find way 
         *Must find way to get rid of duplicate answers 
         */
        final String[] Laws = {"Standard Physics", "Magic", "Mad Science", 
            "Psionics", "Substandard Physics","Exotic"};
            Random random = new Random();
            int index = random.nextInt(Laws.length);
            System.out.println("Law:" + Laws[index]);
    }

    else if (seed == 2) {

        final String[] Laws = {"Standard Physics", "Magic", "Mad Science", 
            "Psionics", "Substandard Physics","Exotic"};
            Random random = new Random();
            int index = random.nextInt(Laws.length);
            int index2 = random.nextInt(Laws.length);
            System.out.println("Law:" + Laws[index] + "," + Laws[index2]);

    }

    else {

        final String[] Laws = {"Standard Physics", "Magic", "Mad Science", 
            "Psionics", "Substandard Physics","Exotic"};
            Random random = new Random();
            int index = random.nextInt(Laws.length);
            int index2 = random.nextInt(Laws.length);
            int index3 = random.nextInt(Laws.length);
            System.out.println("Law: " + Laws[index] + "," + Laws[index2] + 
                    "," + Laws[index3]);

    }

Answer 1

解决这个问题的另一种方法是： 您想以随机顺序选择值。 这样，除非一个元素出现多次，否则您将不会获得重复。

List<String> laws = Arrays.asList("Standard Physics", "Magic", "Mad Science", 
        "Psionics", "Substandard Physics","Exotic");
Collections.shuffle(laws);
// select as many as you need
List<String> lawsSelected = laws.subList(0, 3);

Answer 2

这是一种方法。 您有3个if条件，因此需要3个布尔变量并将每个if关联一个，并在执行if时将其设为true。

Random seeds = new Random(); 
    seed = seeds.nextInt(3) + 1; 


boolean selected[] = new boolean[3];
selected[0] = selected[1] = selected[2] = false;//initially none of the if is executed

    if (seed == 1 && !selected[seed-1]){//checking if not previously selected and "seed-1" since array indexes are from 0 to n-1


        /**Beginning of random law selection for universe. Must find way 
         *Must find way to get rid of duplicate answers 
         */
        final String[] Laws = {"Standard Physics", "Magic", "Mad Science", 
            "Psionics", "Substandard Physics","Exotic"};
            Random random = new Random();
            int index = random.nextInt(Laws.length);
            System.out.println("Law:" + Laws[index]);
            selected[seed-1] = true;
    }

    else if (seed == 2 && !selected[seed-1]) {

        final String[] Laws = {"Standard Physics", "Magic", "Mad Science", 
            "Psionics", "Substandard Physics","Exotic"};
            Random random = new Random();
            int index = random.nextInt(Laws.length);
            int index2 = random.nextInt(Laws.length);
            System.out.println("Law:" + Laws[index] + "," + Laws[index2]);
            selected[seed-1] = true;
    }

    else if (!selected[seed-1]){

        final String[] Laws = {"Standard Physics", "Magic", "Mad Science", 
            "Psionics", "Substandard Physics","Exotic"};
            Random random = new Random();
            int index = random.nextInt(Laws.length);
            int index2 = random.nextInt(Laws.length);
            int index3 = random.nextInt(Laws.length);
            System.out.println("Law: " + Laws[index] + "," + Laws[index2] + 
                    "," + Laws[index3]);
        selected[seed-1] = true;
    }