从对象数组中获取随机对象

Question

我想在循环的每次迭代中获得不同的对象。我从另一个方法中定义的对象数组中获取对象并在此方法中使用，但对象（书）保持不变。 对于每个循环，后面跟着其他语句并正常工作，因此没有相关性。

public static String [] runSimulation(LibraryBook [] bookStock, int numberOFevents){
    Random rnd = new Random();
    String [] output = new String [numberOFevents];
    int a = rnd.nextInt(100);
    int n = LibraryBook.getBooks();
    int c = rnd.nextInt(1);
    int random = rnd.nextInt(n-1);
    //for (int index=0; index<numberOFevents; index++) {
    int i=0;
    for (LibraryBook book : bookStock ){
        i++;
        book = bookStock[random];
        if (book.getLibraryClass() == null) {
            book.setLibraryClass("QA" + a ); 
            output[i] += (i + book.getLibraryClass()+ "BOOK IS CLASSIFIED");
        }
        else if (book.getLibraryClass() != null && 
            "REFERENCE_ONLY".equals(book.getBookStatus())){
            output[i] += (i + book.getLibraryClass() + "REFERENCE ONLY BOOK");
        }

Answer 1

因为您不是每次都在循环中随机更改。您的代码应如下所示：

    int random;
    int i=0;
    for (LibraryBook book : bookStock ){
        i++;
        random = rnd.nextInt(n-1); // sets a new value in every loop
        book = bookStock[random];