/*
①定义方法filter
要求如下：
形参：String [] arr，String str
返回值类型：String []
实现：遍历arr，将数组中以参数str开头的元素存入另一个String 数组中并返回
PS：返回的数组长度需要用代码获取
②在main方法中完成以下要求：
定义一个String数组arr，数组元素有："itcast","itheima","baitdu","weixin","zhifubao"
调用filter方法传入arr数组和字符串”it”，输出返回的String数组中所有元素
示例如下：itcast itheima
*/
public static void main(String[] args) {
String[] arr = {"itcast", "weixin", "baitdu", "itheima", "zhifubao"};
String[] newArray = filter(arr, "it");
for (int i = 0; i < newArray.length; i++) {
System.out.print(newArray[i] + " ");
}
}
public static String[] filter(String[] arr, String str) {
int count = 0;
for (int i = 0; i < arr.length; i++) {
String substring = arr[i].substring(0, 2);
if ("it".equals(substring)) {
count++;
}
}
String[] newArray = new String[count];
int a = 0;
for (int i = 0; i < arr.length; i++) {
if ("it".equals(arr[i].substring(0, 2))) {
newArray[a] = arr[i];
a++;
}
}
return newArray;
}