java算法，队列为空和已满？

[thisisall]

下面代码中，为空和已满，什么意思？为什么那么表示？
public class Queue {

private int maxSize;
private long[] queArray;
private int front;
private int rear;


public Queue(int s){

maxSize=s+1;
queArray=new long[maxSize];
front=0;
rear=-1;

}

public void insert(long j){
if(rear==(maxSize-1))
rear=-1;
queArray[++rear]=j;

}

public long remove(){
if(front==maxSize-1)
front=0;
return queArray[front++];
}

public long peek(){
return queArray[front];
}

public boolean isEmpty(){
return (rear+1==front)||(front+maxSize-1==rear);
}

public boolean isFull(){
return (rear+2==front)||(front+maxSize-2==rear);;
}

public int size(){
return nItems;
}

}

[zdeepblue]

循环队列，书上有的
就是rear会折返到front的前面，所以注意点是临界条件的判断