数组(一)------模拟ArrayList

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package dataStructure;/** * 面向对象方式的对数组封装， 模拟ArrayList * @author wangtao * @date 2016-10-19 上午9:39:43   * @version v1.0   * @TODO 描述 */public class MyArray {private long[] arr;private int elements;public MyArray(){arr = new long[50];}/** * 添加数据 */public void insert(long value){arr[elements] = value;elements++;/*针对有序数据的插入 * int i ;for(i = 0; i < elements; i++){if(arr[i] > value){break;}}//需要倒着来for(int j = elements; j > i ; j--){arr[j] = arr[j-1];}arr[i] = value;elements++;*/}/** * 显示数据 */public void display(){System.out.println("{");for(int i = 0; i < elements; i++){System.out.println(arr[i] + " ");}System.out.println("}");}/** * 线性查找数据 */public int search(long value){int i ;for(i = 0; i < elements; i++){if(value == arr[i]){break;}}if(i == elements){return -1;}return i;}/** * 二分法查找， 前提是数据是有顺序的 * @return */public int binarySearch(long value){int middle = 0;int low = 0;int pow = elements;while(true){middle = (pow + low)/2;if(arr[middle] == value){return middle;}else if(low > pow){return -1;}else{if(arr[middle] > value){pow = middle - 1;}else{low = middle + 1;}}}}/** * 查找数据，根据索引来查 * @return */public long get(int index){if(index >= elements || index < 0){throw new ArrayIndexOutOfBoundsException();}return arr[index];}/** * 删除数据 * @param index */public void delete(int index){if(index >= elements || index < 0){throw new ArrayIndexOutOfBoundsException();} else{for(int i = index; i < elements; i++){arr[index] = arr[index+1];}elements--;}}/** * 更新数据 */public void change(int index, long newvalue){if(index >= elements || index < 0){throw new ArrayIndexOutOfBoundsException();}else{arr[index] = newvalue;}}}
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