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1
7
8 package com.sun.jmx.remote.internal;
9
10 import java.util.AbstractList  ;
11 import java.util.Iterator ;
12
13 public class ArrayQueue<T> extends AbstractList <T> {
14 public ArrayQueue(int capacity) {
15 this.capacity = capacity + 1;
16 this.queue = (T[]) new Object [capacity + 1];
17 this.head = 0;
18 this.tail = 0;
19 }
20
21 public void resize(int newcapacity) {
22 int size = size();
23 if (newcapacity < size)
24 throw new IndexOutOfBoundsException ("Resizing would lose data");
25 newcapacity++;
26 if (newcapacity == this.capacity)
27 return;
28 T[] newqueue = (T[]) new Object [newcapacity];
29 for (int i = 0; i < size; i++)
30 newqueue[i] = get(i);
31 this.capacity = newcapacity;
32 this.queue = newqueue;
33 this.head = 0;
34 this.tail = size;
35 }
36
37 public boolean add(T o) {
38 queue[tail] = o;
39 int newtail = (tail + 1) % capacity;
40 if (newtail == head)
41 throw new IndexOutOfBoundsException ("Queue full");
42 tail = newtail;
43 return true; }
45
46 public T remove(int i) {
47 if (i != 0)
48 throw new IllegalArgumentException ("Can only remove head of queue");
49 if (head == tail)
50 throw new IndexOutOfBoundsException ("Queue empty");
51 T removed = queue[head];
52 queue[head] = null;
53 head = (head + 1) % capacity;
54 return removed;
55 }
56
57 public T get(int i) {
58 int size = size();
59 if (i < 0 || i >= size) {
60 final String msg = "Index " + i + ", queue size " + size;
61 throw new IndexOutOfBoundsException (msg);
62 }
63 int index = (head + i) % capacity;
64 return queue[index];
65 }
66
67 public int size() {
68 int diff = tail - head;
70 if (diff < 0)
71 diff += capacity;
72 return diff;
73 }
74
75 private int capacity;
76 private T[] queue;
77 private int head;
78 private int tail;
79 }
80 |
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