检查语法错误public class Test01 { public static void main(String[] args) { int[] arr = {0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20}; int element = 18; System.out.println(element + "在数组中的索引位置为：" + mid); System.out.println(element + "在数组中的索引位置为：" + -1); } public static int binarySearch(int[] arr,int element) { int min = 0; int max = arr.length - 1; while (true) { int mid = (min + max) / 2; if (element > arr[mid]) { min = mid + 1; } else if (element < arr[mid]) { max = mid - 1; } else { return mid; } if (min > max) { return -1; } } } }

在main方法中，需要调用binarySearch方法获取索引位置，而mid变量未定义。修改为以下代码即可：

public class Test01 {
    public static void main(String[] args) {
        int[] arr = {0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20};
        int element = 18;
        int index = binarySearch(arr, element);
        System.out.println(element + "在数组中的索引位置为：" + index);
        if (index == -1) {
            System.out.println("元素不在数组中");
        }
    }

    public static int binarySearch(int[] arr, int element) {
        int min = 0;
        int max = arr.length - 1;
        while (true) {
            int mid = (min + max) / 2;
            if (element > arr[mid]) {
                min = mid + 1;
            } else if (element < arr[mid]) {
                max = mid - 1;
            } else {
                return mid;
            }
            if (min > max) {
                return -1;
            }
        }
    }
}