package test.string;

import java.util.Arrays;

import java.util.List;

public class GetFileType {

    private static List<String> accTypes = Arrays.asList("jpg","bmp","gif","doc","docx","rar");

    public static void main(String[] args){

        for(String arg:args){

            String type = getFileType(arg);

            if(accTypes.contains(type)){

                System.out.println(arg+"后缀合法");

            }else{

                System.out.println(arg+"后缀不合法");

            }

        }

    }

    /**

     * 获取文件后缀名

     * @param filename

     * @return

     */

    public static String getFileType(String filename){

        int pos = filename.lastIndexOf(".");

        if(pos == -1){

            return null;

        }

        return filename.substring(pos+1);

    }

}