JavaArithmetic/src/datastructure/array/Array.java at master · sqlcyi2008/JavaArithmetic · GitHub

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package datastructure.array;

public class Array<E> {

private E[] data;

private int size;

// 构造函数，传入数组的容量capacity构造Array

public Array(int capacity) {

data = (E[]) new Object[capacity];

size = 0;

}

// 无参数的构造函数，默认数组的容量capacity=10

public Array() {

this(10);

}

// 获取数组的容量

public int getCapacity() {

return data.length;

}

// 获取数组中的元素个数

public int getSize() {

return size;

}

// 返回数组是否为空

public boolean isEmpty() {

return size == 0;

}

// 在index索引的位置插入一个新元素e

public void add(int index, E e) {

if (index < 0 || index > size)

throw new IllegalArgumentException("Add failed. Require index >= 0 and index <= size.");

if (size == data.length)

resize(2 * data.length);

for (int i = size - 1; i >= index; i--)

data[i + 1] = data[i];

data[index] = e;

size++;

}

// 向所有元素后添加一个新元素

public void addLast(E e) {

add(size, e);

}

// 在所有元素前添加一个新元素

public void addFirst(E e) {

add(0, e);

}

// 获取index索引位置的元素

public E get(int index) {

if (index < 0 || index >= size)

throw new IllegalArgumentException("Get failed. Index is illegal.");

return data[index];

}

// 修改index索引位置的元素为e

public void set(int index, E e) {

if (index < 0 || index >= size)

throw new IllegalArgumentException("Set failed. Index is illegal.");

data[index] = e;

}

// 查找数组中是否有元素e

public boolean contains(E e) {

for (int i = 0; i < size; i++) {

if (data[i].equals(e))

return true;

}

return false;

}

// 查找数组中元素e所在的索引，如果不存在元素e，则返回-1

public int find(E e) {

for (int i = 0; i < size; i++) {

if (data[i].equals(e))

return i;

}

return -1;

}

// 从数组中删除index位置的元素, 返回删除的元素

public E remove(int index) {

if (index < 0 || index >= size)

throw new IllegalArgumentException("Remove failed. Index is illegal.");

E ret = data[index];

for (int i = index + 1; i < size; i++)

data[i - 1] = data[i];

size--;

data[size] = null; // loitering objects != memory leak

if (size == data.length / 4 && data.length / 2 != 0)

resize(data.length / 2);

return ret;

}

// 从数组中删除第一个元素, 返回删除的元素

public E removeFirst() {

return remove(0);

}

// 从数组中删除最后一个元素, 返回删除的元素

public E removeLast() {

return remove(size - 1);

}

// 从数组中删除元素e

public void removeElement(E e) {

int index = find(e);

if (index != -1)

remove(index);

}

@Override

public String toString() {

StringBuilder res = new StringBuilder();

res.append(String.format("Array: size = %d , capacity = %d\n", size, data.length));

res.append('[');

for (int i = 0; i < size; i++) {

res.append(data[i]);

if (i != size - 1)

res.append(", ");

}

res.append(']');

return res.toString();

}

// 将数组空间的容量变成newCapacity大小

private void resize(int newCapacity) {

E[] newData = (E[]) new Object[newCapacity];

for (int i = 0; i < size; i++)

newData[i] = data[i];

data = newData;

}

JavaArithmetic/src/datastructure/array/Array.java at master · sqlcyi2008/JavaArithmetic · GitHub

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