在
我正在尝试将随机整数插入从最小到最大的链接列表中。每次我运行此方法时，都会开始分类和打印，但最终会给我一个NullPoInterException吗？任何帮助都将不胜感激。
public void insertInOrder(int x) {
if (head == null) {
head = new Node(x);
} else {
Node prev;
Node curr;
for (prev = null, curr = head;
(curr != null) && (x > curr.getNumber());
prev = curr, curr = curr.getNext()) {}
if (prev == null) {
insertAtHead(x);
}
if (curr == null) {
insertAtTail(x);
} else {
Node nNex = new Node(x);
nNex.setNext(curr);
prev.setNext(nNex); // NullPointerException is raised here
}
}
}
这就是您拥有的
if (prev == null) {
insertAtHead(x);
}
if (curr == null) {
insertAtTail(x);
} else {
Node nNex = new Node(x);
nNex.setNext(curr);
prev.setNext(nNex);
}
您检查上述是否为null，是否在第一个if语句中进行，但是如果您输入ELSE语句prev仍然为null。您应该这样做：
if (prev == null) {
insertAtHead(x);
}
else if (curr == null) {
insertAtTail(x);
} else {
Node nNex = new Node(x);
nNex.setNext(curr);
prev.setNext(nNex);
}