java - 数组空指针异常

Question

这个问题已经有答案了:

What is a NullPointerException, and how do I fix it? (12 个回答)

已关闭 7 年前。

我在第 行遇到空指针异常

if(names[j].compareTo(names[j+1]) > 0)

我不明白为什么。它可能与初始化有关，但我真的不知道它可能是什么

public static void item3(Profitable[] movies, Scanner input) {
    int j;
    boolean flag = true;
    String temp;
    String search;
    int low = 0;
    int high;
    int mid;

    String[] names = new String[6];

    for(int i = 0; i < 5; i++) {
        names[i] = ((Movie)movies[i]).getTitle();
    }

    high = names.length - 1;
    mid = (low + high) / 2;

    while(flag)
    {
        flag = false;
        for(j = 0; j < names.length - 1; j++)
        {

            if(names[j].compareTo(names[j+1]) > 0) {
                temp = names[j];
                names[j] = names[j+1];
                names[j+1] = temp;
                flag = true;
            }
        }
    }

    System.out.print("Enter your search term: ");
    search = input.nextLine();

}

Answer 1

这个循环:

for(int i = 0; i < 5; i++) {
    names[i] = ((Movie)movies[i]).getTitle();
}

仅初始化前五个元素，但最后一个元素不会被初始化。