数组的复制、反转、查找(线性查找、二分法查找)(java)

public class ArrayTest2 {
    
    public static void main(String[] args) {
        
        String[] arr = new String[]{"JJ","DD","MM","BB","GG","AA"};
        
        
        //数组的复制(区别于数组变量的赋值:arr1 = arr)
        String[] arr1 = new String[arr.length];
        for(int i = 0;i < arr1.length;i++){
            arr1[i] = arr[i];
        }
        
        //数组的反转
        //方法一:
//        for(int i = 0;i < arr.length / 2;i++){
//            String temp = arr[i];
//            arr[i] = arr[arr.length - i -1];
//            arr[arr.length - i -1] = temp;
//        }
        
        //方法二:
//        for(int i = 0,j = arr.length - 1;i < j;i++,j--){
//            String temp = arr[i];
//            arr[i] = arr[j];
//            arr[j] = temp;
//        }
        
        //遍历
        for(int i = 0;i < arr.length;i++){
            System.out.print(arr[i] + "\t");
        }
        
        System.out.println();
        //查找(或搜索)
        //线性查找:
        String dest = "BB";
        dest = "CC";
        
        boolean isFlag = true;
        
        for(int i = 0;i < arr.length;i++){
            
            if(dest.equals(arr[i])){
                System.out.println("找到了指定的元素,位置为:" + i);
                isFlag = false;
                break;
            }
            
        }
        if(isFlag){
            System.out.println("很遗憾,没有找到的啦!");
            
        }
        //二分法查找:(熟悉)
        //前提:所要查找的数组必须有序。
        int[] arr2 = new int[]{-98,-34,2,34,54,66,79,105,210,333};
        
        int dest1 = -34;
        dest1 = 35;
        int head = 0;//初始的首索引
        int end = arr2.length - 1;//初始的末索引
        boolean isFlag1 = true;
        while(head <= end){
            
            int middle = (head + end)/2;
            
            if(dest1 == arr2[middle]){
                System.out.println("找到了指定的元素,位置为:" + middle);
                isFlag1 = false;
                break;
            }else if(arr2[middle] > dest1){
                end = middle - 1;
            }else{//arr2[middle] < dest1
                head = middle + 1;
            }

            
        }
        
        if(isFlag1){
            System.out.println("很遗憾,没有找到的啦!");
        }
        
        
    }
}

 

posted @ 2020-08-19 18:14  兔奶糖  阅读(150)  评论(0)    收藏  举报