java - java中for循环中的越界异常打印小于数组列表大小

Question

即使我在 for 循环中明确指定我希望它打印到 arraylist.size，终端也会返回 OutOfBounds 异常

public static void PrintPlayList() {
        int lengthsongs = songs.size();
        int lengthadds = adds.size();
        int amountadds = 0;

    for (int i = 0; i < lengthsongs; i++) {
        playlist.add(songs.get(i));
        if (amountadds < lengthadds) {
            playlist.add(adds.get(amountadds));
            amountadds++;
        }
    }

    int lengthplaylist = playlist.size();
    for (int i = 0; i < lengthplaylist; i++) {
        System.out.println(songs.get(i).toString());
        System.out.println(adds.get(i).toString());
    }
}

And this is what the compiler returns: How is it possible? How can I fix it?

java.lang.IndexOutOfBoundsException: Index: 18, Size: 18
    at java.util.ArrayList.rangeCheck(Unknown Source)
    at java.util.ArrayList.get(Unknown Source)
    at Main.PrintPlayList(Main.java:153)
    at Main.Interface(Main.java:55)
    at Main.main(Main.java:34)

Answer 1

我认为问题出在这里:

for (int i = 0; i < lengthplaylist; i++) {
        System.out.println(songs.get(i).toString());
        System.out.println(adds.get(i).toString());
    }

代码中的

lengthplaylist 可以大于 lengthsongs。并且您使用 for 循环从 0 到 lengthplaylist 而不是 lengthsongs。

您还应该注意 adds.get(i).toString() 因为要执行此操作，所有长度都必须相同。

您可以在循环中为它们使用不同的变量，如下所示:

for (int i = 0,j=0; i < lengthsongs && j<lengthadds; i++,j++) {
        System.out.println(songs.get(i).toString());
        System.out.println(adds.get(j).toString());
}