import java.util.Scanner; public class FileFilter{ public static void main(String[] args) { Scanner scanner=new Scanner(System.in); String[] filenames=new String[2]; int i=0; for(i=0;i<filenames.length;i++){ System.out.println("please input the string"); String text=scanner.next();      filenames[i]=text;} System.out.println("output the filterfile:"); if(filenames[i].endsWith("jpg")){ System.out.println(filenames[i]); } } } 這樣做為什么不行呢