数组的复制/反转/查找（线性，二分法）

标签：bool   ring   有序   str   length   false   组的复制   boolean   else   

public class ArrayListTest {
    public static void main(String[] args) {
        String[] arr = new String[]{"AA", "BB", "CC", "DD", "EE"};

        // 数组的复制
        String[] arr1 = new String[arr.length];
        for (int i = 0; i < arr1.length; i++) {
            arr1[i] = arr[i];
            System.out.print(arr1[i] + "\t");
        }
        System.out.println();

        // 数组的反转,两个方法
        String arr2[] = new String[arr.length];
        for (int i = 0; i < arr.length; i++) {
            arr2[i] = arr[arr.length - i-1];

        }
        // 遍历
        for (int i = 0; i < arr2.length; i++) {
            System.out.print(arr2[i] + "\t");
        }
        for (int i = 0,j = arr.length -1;i<j; i++,j--) {
            String temp = arr[i];
            arr[i] = arr[j];
            arr[j] = temp;
        }
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + "\t");
        }

        System.out.println();
        // 数组的查找,线性查找，
//        String dest = "BB";
        String dest = "JJ";

        boolean isFlag = true;
        for (int i = 0; i < arr.length; i++) {
            if (dest.equals(arr[i])) {
                System.out.println("找到了,"+dest +"的位置为" + (i + 1));
                isFlag = false;
                break;
            }
        }
        if (isFlag) {
            System.out.println("很遗憾，" +dest+ "没有找到");
        }

        // 二分法查找,比线性快.前提找的数组必须是有序的

        int[] arrSelect = new int[]{-5, -1, 0,1, 5, 7, 11, 56};
        int selectNumber = 0;
        selectNumber = 100;
        int head = 0;
        int end = arrSelect.length - 1;
        boolean isFlag1 = true;
        while (head <= end) {
            int middle = (head + end) / 2;

            if (selectNumber == arrSelect[middle]) {
                System.out.println("找到了，位置为：" + middle);
                isFlag1 = false;
                break;
            } else if (arrSelect[middle] > selectNumber) {
                end = middle - 1;
            } else { // arrSelect[middle] < select
                head = middle + 1;
            }
        }
        if (isFlag1) {
            System.out.println("抱歉，没找到" + selectNumber);

        }
    }
}

数组的复制/反转/查找（线性，二分法）

标签：bool   ring   有序   str   length   false   组的复制   boolean   else   

原文地址：https://www.cnblogs.com/xjxlovehmx/p/14383082.html