实现数组_2_泛型

在创造自己的数组_1中，数组内存储数据只支持int类型，我们现在改成泛型。

package com.company;

/**
 * @program: Array
 * @description: 数组
 * @author: Gu
 * @create: 2019-04-10 22:03
 **/

public class Array<E> {

    private E[] data;
    private int size;

    //初始化
    public Array(int capacity) {
        data = (E[])new Object[capacity];
        size = 0;
    }

    //无参构造函数默认最大容量为10
    public Array() {
        this(10);
    }

    //数组长度
    public int length() {
        return data.length;
    }

    //数组元素个数
    public int getSize() {
        return size;
    }

    //数组是否为空
    public boolean isEmpty() {
        return size == 0;
    }
    //向数组指定位置中添加元素
    public void add(int index, E element) {
        if (index >= data.length || index < 0) {
            throw new IllegalArgumentException("[数组索引非法]");
        }

        if (size >= data.length) {
            throw new IndexOutOfBoundsException("[数组已达到最大容量]");
        }

        for (int i = size - 1; i >= index; i--) {
            data[i + 1] = data[i];
        }
        data[index] = element;
        size++;
    }

    //向数组第一个索引添加元素
    public void addFirst(E element) {
        add(0, element);
    }

    //数组末尾添加元素
    public void addLast(E element) {
        add(size, element);
    }

    //根据index查找指定元素
    public E get(int index) {
        if (index < 0 || index >= size) {
            throw new IllegalArgumentException("[数组索引非法]");
        }
        return data[index];
    }

    //查找数组是否包含指定元素
    public boolean contains(E element) {
        for (E value : data) {
            if (value.equals(element)) {
                return true;
            }
        }
        return false;
    }

    //返回指定元素的索引
    public int find(E element) {
        for (int i = 0; i < size; i++) {
            if (data[i].equals(element)) {
                return i;
            }
        }
        return -1;
    }


    //修改数组元素
    public void set(int index, E element) {
        if (index < 0 || index >= size) {
            throw new IllegalArgumentException("[数组索引非法]");
        }
        data[index] = element;
    }

    //删除指定元素
    public void delete(E element) {
        int index = find(element);
        if (index == -1) {
            throw new IllegalArgumentException("[数组没有该元素]");
        }
        remove(index);
    }

    //根据索引删除元素
    public E remove(int index) {
        if (index < 0 || index >= size) {
            throw new IllegalArgumentException("[数组索引非法]");
        }
        E res = data[index];
        for (int i = index + 1; i < size; i++) {
            data[i - 1] = data[i];
        }
        size = size - 1;
        //改成泛型之后，最后一个内容要删除，清空内存，不删除也可以
        data[size] = null;
        return res;
    }

    //删除第一个
    public E removeFirst() {
        return remove(0);
    }

    //删除最后一个
    public E removeLast() {
        return remove(size - 1);
    }

    //打印数组相关信息
    @Override
    public String toString() {
        StringBuffer stringBuffer = new StringBuffer();
        stringBuffer.append(String.format("数组的size : %d, 数组的capacity : %d \n", size, data.length));
        stringBuffer.append("[");
        for (int i = 0; i < size; i++) {
            stringBuffer.append(data[i]);
            if (i == size - 1) {
                stringBuffer.append("]");
                break;
            }
            stringBuffer.append(",");
        }
        return stringBuffer.toString();
    }

}

测试类

package com.company;

public class Main {

    public static void main(String[] args) {

    //add()
    Array<Integer> array = new Array<>(20);
    for (int i = 0; i < 10; i++) {
        array.add(i, i + 1);
    }
    System.out.println(array);
    //[1,2,3,4,5,6,7,8,9,10]

    //addFirst()
    array.addFirst(0);
    System.out.println(array);
    //[0,1,2,3,4,5,6,7,8,9,10]

    //addLast()
    array.addLast(11);
    System.out.println(array);
    //[0,1,2,3,4,5,6,7,8,9,10,11]

    // get()
    System.out.println(array.get(0));
    //0

     System.out.println(array.contains(0));
     //true

     System.out.println(array.find(0));
     //0

     //set()
     array.set(0, -2);
     System.out.println(array);

     //removeFirst
     array.removeFirst();
     System.out.println(array);
    }
}

测试Student类

package com.company;

/**
 * @program: Array
 * @description: 用于数组泛型测试
 * @author: Gu
 * @create: 2019-04-11 20:31
 **/

public class Student {

    private String name;

    private int age;

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    private void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    private void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return String.format("name : %s, age : %d", name, age);
    }

    public static void main(String[] args) {
        Array<Student> array = new Array<>();
        array.add(0,new Student("aa", 11));
        array.add(1, new Student("bb",22));
        System.out.println(array);
    }
}