抱歉,接下来是我在这里提出的问题:here https://stackoverflow.com/questions/4927026/double-sided-queue-problem我正在尝试运行此方法以从双面队列(双端队列)中删除通用值(EltType),但我不断收到错误,我调用 insertFirst 两次,并将值“3”插入数组两次,然后,当我运行removeFirst时,它将打印一次“3”,然后打印“Null”。有人能帮我吗?
class ArrayBasedDeque<EltType> {
private final int CAPACITY = 10;
private int capacity;
private int end;
private EltType deque[];
public ArrayBasedDeque() {
this.capacity = CAPACITY;
deque = (EltType[]) (new Object[capacity]);
}
public EltType removeFirst() {
EltType[] tempArray;
EltType returned = deque[0];
tempArray = (EltType[]) new Object[capacity];
for (int i=1;i<capacity;i++) {
tempArray[i-1] = deque[i];
}
deque = tempArray;
return returned;
}
public boolean isEmpty() {
return end == 0;
}
public void insertFirst(EltType first) {
if(!isEmpty()) {
EltType[] tempArray;
tempArray = (EltType[]) new Object[capacity+1];
for (int i=0;i<deque.length;i++) {
tempArray[i+1] = deque[i];
}
deque = tempArray;
}
deque[0] = first;
}
}
谢谢 :)
最明显的问题是end
永远不会改变。isEmpty()
总会回来的true
。现在让我们看看你的insertFirst()
method.
public void insertFirst(EltType first) {
if(!isEmpty()) {
EltType[] tempArray;
tempArray = (EltType[]) new Object[capacity+1];
for (int i=0;i<deque.length;i++) {
tempArray[i+1] = deque[i];
}
deque = tempArray;
}
deque[0] = first;
}
知道isEmpty()
总是返回true
不管怎样,这段代码有什么问题吗?
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