java数据结构之数组

package demo01;

import java.util.Arrays;

public class MyArray {
    private int[] elements;

    public MyArray()
    {
        elements = new int[0];
    }

    //获取长度
    public int size()
    {
        return elements.length;
    }

    //添加元素
    public void add(int element){
        int[] newArr = new int[elements.length+1];
        for(int i = 0;i < elements.length;i++)
        {
            newArr[i] = elements[i];
        }
        newArr[elements.length] = element;
        elements = newArr;//新数组替换旧数组
    }

    //打印元素
    public void printArray()
    {
        System.out.println(Arrays.toString(elements));
    }

    //删除元素
    public void delete(int index)
    {
        if(index < 0 || index > elements.length-1)
        {
            throw new RuntimeException("下标越界");
        }

        int[] newArr = new int[elements.length-1];
        for(int i = 0;i < newArr.length;i++)
        {
            if(i < index)
            {
                newArr[i] = elements[i];
            }
            else{
                newArr[i] = elements[i+1];
            }

            elements = newArr;
        }
    }

    //获取指定位置的元素
    public int get(int index){
        return elements[index];
    }

    //在某个位置插入一个元素
    public void insert(int pos,int value)
    {
        if(pos < 1 || pos > elements.length+1)
        {
            System.out.println("插入位置不合法");
            return;
        }
        int[] newArr = new int[elements.length+1];
        for(int i = 0;i <= elements.length;i++)
        {
            if(i < pos-1)
            {
                newArr[i] = elements[i];
            }
            else if(i == pos-1)
            {
                newArr[i] = value;
            }
            else
            {
                newArr[i] = elements[i-1];
            }
        }


        elements = newArr;
    }

    //替换指定位置的元素
    public void set(int pos,int value)
    {
        if(pos < 1 || pos > elements.length)
        {
            System.out.println("替换位置有误");
            return;
        }
        elements[pos-1] = value;
    }

    //线性查找
    public int search(int target)
    {
        int index = -1;
        for(int i = 0;i < elements.length;i++)
        {
            if(elements[i] == target){
                index = i;
                break;
            }
        }
        return index;
    }

    //二分查找找--查找的目标数组必须是有序的
    public int binarySearch(int target)
    {
        int index = -1;

        int begin = 0;
        int end = elements.length-1;
        int middle;

        //循环查找
        while(true)
        {
            middle = (begin+end)/2;

            if(begin >= end)//出现这种情况,说明目标元素不存在
            {
                break;
            }
            if(elements[middle] == target)//判断中间的元素是不是要查找的元素
            {
                index = middle;
                break;
            }
            else if(elements[middle] > target)
            {
                end = middle-1;
            }
            else
            {
                begin = middle+1;
            }
        }
        return index;
    }

}