我将如何得到不使用`import java.util.Random`的重复结果？

Question

美好的一天！我是编程的初学者，我一直在编写一个程序。它使用import java.util.Random，因为我希望我的问题以任意顺序随机出现。但问题和唯一的问题是这个问题重复。例如，“你快乐吗？”被问了三次，“你想要iPhone 5吗？”甚至没有被问到。我应该怎么做才能以不特定的顺序显示所有问题，因此它不会多次选择相同的问题？到目前为止，这就是我所拥有的。

import java.util.Random; 
public class RandomQuiz { 
    public static void main (String args []){ 
     int a, b=0; 
     String arr []; 
     arr = new String [5]; 
     a = b; 
     arr [a] = "Are you happy? \na. yes\t\tb. no\nc. maybe\td. no comment"; 
     a = b+1; 
     arr [a] = "Did you eat breakfast? \na. yes\t\tb. no\nc. maybe\td. no comment"; 
     a = b+2; 
     arr [a] = "Have you watched tv? \na. yes\t\tb. no\nc. maybe\td. no comment"; 
     a = b+3; 
     arr [a] = "Do you want iPhone 5? \na. yes\t\tb. no\nc. maybe\td. no comment"; 
     a = b+4; 
     arr [a] = "Will you have iPad mini? \na. yes\t\tb. no\nc. maybe\td. no comment"; 

     //prints array values in random 
     Random randnum = new Random(); 
     for (int count = 1; count <=5; count++){ 
      a = randnum.nextInt (5); 
      System.out.println ("Question # " + count + "\n" + arr [a]); 
     } 
    } 
} 

Answer 1

试试这个

Random randnum = new Random (System.currentTimeMillis()); 
    java.util.HashSet<Integer> myset = new java.util.HashSet<Integer>(); 
    for (int count = 1; count <=5; count++){ 
     while(true) { 
      a = randnum.nextInt (5) ; 
      if(!myset.contains(a)) { myset.add(new Integer(a)); break;} 
     } 
     System.out.println ("Question # " + count + "\n" + arr [a]); 
    } 

Answer 2

1和5之间的真正的随机整数几乎肯定会有重复的数字的大量。如果你只想把数组的元素以随机的顺序，那么你应该使用Collections.shuffle：

public static void main(String[] args) { 
    String[] array = { 
    "Are you happy? \na. yes\t\tb. no\nc. maybe\td. no comment", 
    "Did you eat breakfast? \na. yes\t\tb. no\nc. maybe\td. no comment", 
    "Have you watched tv? \na. yes\t\tb. no\nc. maybe\td. no comment", 
    "Do you want iPhone 5? \na. yes\t\tb. no\nc. maybe\td. no comment", 
    "Will you have iPad mini? \na. yes\t\tb. no\nc. maybe\td. no comment" 
    }; 

    List<String> items = Arrays.asList(array); 
    Collections.shuffle(items); 

    for (int index = 0; index < 5; index++) { 
    System.out.println("Question # " + (index + 1) + "\n" + items.get(index)); 
    } 
}