Java基础__Java中自定义集合类

　　Java基础__Java中集合类　　传送门

　　自定义MyArrayList集合实现：增加数据、取数据、查看集合中数据个数方法

package com.Gary;

public class MyArrayList {

    private int[] dataArray = new int[100];

    private int index = 0;

    public void add(int data) {
        dataArray[index] = data;
        index++;
    }

    public int get(int index) {
        if(index >=0 && index<=(this.index-1) )
        {
            return dataArray[index];
        }else {
            System.out.println("无数据");
            return -1;
        }
    }

    public int size() {

        return index;
    }

}

MyArrayList.java

package com.Gary;

public class Test {
    public static void main(String[] args) {
        MyArrayList list = new MyArrayList();

        //添加数据
        list.add(1);
        list.add(2);
        list.add(3);
        list.add(4);
        list.add(5);

        //输出数据
        //System.out.println(list.get(1));
        //System.out.println(list.get(10));

        System.out.println(list.size());

        for(int i=0;i<list.size();i++)
        {
            System.out.println("输出list中的数据："+list.get(i));
        }

    }
}

Test.java

　　为了适应任意类型的数据，可以将我们自定义的集合类定义为泛型MyArrayList<T>

package com.Gary;

public class Test {
    public static void main(String[] args) {
        //MyArrayList<String>   字符类型
        MyArrayList<Integer> list = new MyArrayList<Integer>();

        list.add(1);
        list.add(2);

        for(int i=0;i<list.size();i++)
        {
            System.out.println(list.get(i));
        }

    }
}

Test.java

package com.Gary;

public class MyArrayList<T> {

    private T[] dataArray = (T[]) new Object[100];

    private int index = 0;

    public void add(T data) {
        dataArray[index] = data;
        index++;
    }

    public T get(int index) {
        if(index >=0 && index<=(this.index-1) )
        {
            return dataArray[index];
        }else {
            System.out.println("无数据");
            return null;
        }
    }

    public int size() {

        return index;
    }

}

MyArrayList.java