人们,我需要你们对这个问题的帮助,因为我找不到合适的解决方案来解决它。“线程中的异常”main“java.lang.NullPointerException”ArrayList
的问题是:
**Exception in thread "main" java.lang.NullPointerException
at edu.maimonides.www.progmul3.tps.tp1.Garage.park(Garage.java:57)
at edu.maimonides.www.progmul3.tps.tp1.GarageElPlus.main(Garage.java:29)
Java Result: 1**
//翻译:汽车=汽车 - 摩托= Motorcicle - Camioneta =凡
**Class Park Slot**
public class Park Slot {
private ArrayList<Integer> bigParkSlot =
new ArrayList<>(Arrays.asList(1, 3, 5, 7, 9, 11));
private ArrayList<Integer> avaliableParkSlot =
new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22));
private Map<Integer, String> busyParkSlot = new HashMap<>();
private ArrayList uncoveredParkSlot =
new ArrayList<>(Arrays.asList(11, 12, 13, 14, 15, 16, 17, 18, 19, 20));
private ArrayList coveredParkSlot =
new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
}
**Class Garage**
// Line 57
// the problem is here
ArrayList<Integer> pElem = c.getavaliableParkSlot();
int num = pElem.iterator().next();
我的猜测是,'C'是*空*当你调用'getavaliableParkSlot() '对此,它抛出错误 – Sujay
这是调试器的用途。在第57行放置一个断点,然后在IDE中按下debug。看看'c'是什么。否则,我们所说的一切都是*心理调试*,我们只是试图猜测。 –