큐 구현

public class Queue {
    private int max;
    private int front; 
    private int rear;
    private int num; //현재 큐에 들어있는 수들의 개수
    private int[] que;
    
    public class EmptyQueueException extends RuntimeException {
        
    }
    
    public class OverflowQueueException extends RuntimeException {
        
    }
    
    public Queue(int capacity) {
        max = capacity;
        front = 0;
        rear = 0;
        num = 0;
        try {
            que = new int[max];
        }catch (OutOfMemoryError e) {
            max = 0;
        }
    }
    
    public int enqueue(int x) throws OverflowQueueException {
        if (num >= max)
            throw new OverflowQueueException();
        que[rear++] = x;
        num++;
        if (rear == max) { 
            rear = 0;
        }
        return x;
    }
    
    public int dequeue() throws IntStack.EmptyStackException {
        if (num <= 0)
            throw new EmptyQueueException();
        int x = que[front++];
        num--;
        if (front == max)
            front = 0;
        return x;
    }
    
    public int peek() throws EmptyQueueException{ //프론트 데이터 조회 
        if (num <= 0)
            throw new EmptyQueueException();
        return que[front];
    }
    
    public int indexOf(int x) { //x가 큐 안에 있는지 검색
        for (int i = 0; i < num; i++) {
            int idx = (i + front) % max;
            if (que[idx] == x) 
                return idx;
        }
        return -1;
    }
    
    public void clear() {
        num = front = rear = 0;
    }
    
    public int capacity() {
        return max;
    }
    
    public int size() {
        return num;
    }
    
    public boolean isEmpty() {
        return num <= 0;
    }
    
    public boolean isFull() {
        return num >= max;
    }
    
    public void dump() { //모든 데이터를 프론트에서 리어 순으로 출력
        if (num <= 0)
            System.out.println("큐가 비었습니다");
        else {
            for (int i = 0; i < num; i++) {
                System.out.println(que[(i+front) % max] + " ");
            }
            System.out.println();
        }
    }
}