数组
查找下标：
class Demo1 {
public static void main(String[] args) {
int [] arr = {1, 3, 23, 34, 5, 56, 7, 8, 9, 10};
int ret = findIndex(arr, 34);
if (ret != -1) {
System.out.println("ret = " + ret );
}else {
System.out.println("not,found.!" );
}
}
public static int findIndex(int[] array,int number) {
if (null == array || array.length == 0) {
System.out.println("传入参数不合法");
return -1;
}
int index = -1;
for (int i = 0; i < array.length; i++) {
if (number == array[i]) {
index = i;
}
}
return index;
}
}
查最大值：
public class Demo2 {
public static void main(String[] args) {
int[] arr = new int[10];
getNumberFromStdin(arr);
int ret = findMaxIndex(arr);
if (ret != -1) {
System.out.println("Max is " + arr[ret] + " at " + ret);
}
}
public static int findMaxIndex(int[] array) {
//1. 参数合法性判断
if (null == array || array.length == 0) {
System.out.println("传入参数不合法！");
return -1;
}
//2. 假设下标为0的元素是数组中的最大值
int index = 0;
for (int i = 1; i < array.length; i++) {
//如果当前index下标的数据小于下标为i的元素，证明当前
//Index保存的不是最大值，把i的值赋值给index 保存
if (array[index] < array[i]) {
index = i;
}
}
return index;
}
public static void getNumberFromStdin(int[] array) {
//1. 参数合法性判断
if (null == array) {
System.out.println("传入参数不合法");
return;
}
Scanner sc = new Scanner(System.in);
//2. 利用for循环从键盘上获取用户输入的int类型数据
for (int i = 0; i < array.length; i++) {
array[i] = sc.nextInt();
}
}
}
