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| 1 | +package Collection; |
| 2 | + |
| 3 | +import com.coding.basic.List; |
| 4 | + |
| 5 | +import java.util.NoSuchElementException; |
| 6 | + |
| 7 | +import com.coding.basic.Iterator; |
| 8 | + |
| 9 | +public class ArrayList implements List { |
| 10 | + |
| 11 | + private int size; |
| 12 | + private Object[] elementData; |
| 13 | + |
| 14 | + public ArrayList() { |
| 15 | + size = 0; |
| 16 | + elementData = new Object[10]; |
| 17 | + } |
| 18 | + |
| 19 | + public ArrayList(Object o) { |
| 20 | + size = 0; |
| 21 | + elementData = new Object[10]; |
| 22 | + this.add(o); |
| 23 | + } |
| 24 | + |
| 25 | + public ArrayList(int initialCapacity) { |
| 26 | + size = 0; |
| 27 | + elementData = new Object[initialCapacity]; |
| 28 | + } |
| 29 | + |
| 30 | + @Override |
| 31 | + public void add(Object o) { |
| 32 | + if (size <= elementData.length - 1) { |
| 33 | + elementData[size] = o; |
| 34 | + size++; |
| 35 | + } else { |
| 36 | + this.extendCapacity(); |
| 37 | + elementData[size] = o; |
| 38 | + size++; |
| 39 | + |
| 40 | + } |
| 41 | + } |
| 42 | + |
| 43 | + @Override |
| 44 | + public void add(int index, Object o) { |
| 45 | + if (index < 0) { |
| 46 | + throw new IndexOutOfBoundsException(); |
| 47 | + } |
| 48 | + if (index > elementData.length - 1) { |
| 49 | + while (index > elementData.length - 1) { |
| 50 | + this.extendCapacity(); |
| 51 | + } |
| 52 | + elementData[index] = o; |
| 53 | + size = index + 1; |
| 54 | + return; |
| 55 | + } |
| 56 | + |
| 57 | + if (index >= size) { |
| 58 | + size = index + 1; |
| 59 | + elementData[index] = o; |
| 60 | + return; |
| 61 | + } |
| 62 | + if (index >= 0 && index < size) { |
| 63 | + this.moveRearward(index); |
| 64 | + elementData[index] = o; |
| 65 | + size++; |
| 66 | + return; |
| 67 | + } |
| 68 | + } |
| 69 | + |
| 70 | + @Override |
| 71 | + public Object get(int index) { |
| 72 | + checkCapacity(index); |
| 73 | + if (index < size) { |
| 74 | + return elementData[index]; |
| 75 | + } |
| 76 | + return null; |
| 77 | + } |
| 78 | + |
| 79 | + @Override |
| 80 | + public Object remove(int index) { |
| 81 | + checkCapacity(index); |
| 82 | + |
| 83 | + if (index == size - 1) { |
| 84 | + size--; |
| 85 | + return elementData[size - 1]; |
| 86 | + } |
| 87 | + if (index < size - 1) { |
| 88 | + Object tmp = elementData[index]; |
| 89 | + for (int i = index; i < size - 1; i++) { |
| 90 | + elementData[i] = elementData[i + 1]; |
| 91 | + } |
| 92 | + size--; |
| 93 | + return tmp; |
| 94 | + } |
| 95 | + return null; |
| 96 | + } |
| 97 | + |
| 98 | + private void checkCapacity(int index) { |
| 99 | + if (index < 0 || index >= size) { |
| 100 | + throw new IndexOutOfBoundsException(); |
| 101 | + } |
| 102 | + } |
| 103 | + |
| 104 | + private void extendCapacity() { |
| 105 | + Object[] elements = new Object[elementData.length + 10]; |
| 106 | + for (int i = 0; i < size; i++) { |
| 107 | + elements[i] = elementData[i]; |
| 108 | + } |
| 109 | + elementData = elements; |
| 110 | + |
| 111 | + } |
| 112 | + |
| 113 | + @Override |
| 114 | + public int size() { |
| 115 | + return size; |
| 116 | + } |
| 117 | + |
| 118 | + public String toString() { |
| 119 | + StringBuilder sb = new StringBuilder(); |
| 120 | + sb.append("["); |
| 121 | + for (int i = 0; i < size; i++) { |
| 122 | + sb.append(elementData[i]); |
| 123 | + sb.append(","); |
| 124 | + } |
| 125 | + sb.deleteCharAt(sb.length() - 1); |
| 126 | + sb.append("]"); |
| 127 | + return sb.toString(); |
| 128 | + } |
| 129 | + |
| 130 | + private void moveRearward(int index) { |
| 131 | + size++; |
| 132 | + |
| 133 | + if (size >= elementData.length - 1) |
| 134 | + this.extendCapacity(); |
| 135 | + |
| 136 | + for (int i = size - 1; i > index; i--) { |
| 137 | + elementData[i] = elementData[i - 1]; |
| 138 | + } |
| 139 | + } |
| 140 | + |
| 141 | + public Iterator iterator() { |
| 142 | + return new ArrayListIterator(); |
| 143 | + } |
| 144 | + |
| 145 | + private class ArrayListIterator implements Iterator { |
| 146 | + |
| 147 | + private int pos; |
| 148 | + |
| 149 | + public ArrayListIterator() { |
| 150 | + |
| 151 | + pos = 0; |
| 152 | + } |
| 153 | + |
| 154 | + @Override |
| 155 | + public boolean hasNext() { |
| 156 | + if (pos < size) { |
| 157 | + return true; |
| 158 | + } |
| 159 | + return false; |
| 160 | + } |
| 161 | + |
| 162 | + @Override |
| 163 | + public Object next() { |
| 164 | + if (hasNext()) { |
| 165 | + return elementData[pos++]; |
| 166 | + } else |
| 167 | + throw new NoSuchElementException(); |
| 168 | + |
| 169 | + } |
| 170 | + |
| 171 | + } |
| 172 | + |
| 173 | +} |
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