求大神，赐教 结果为什么和答案是相反的
package com.imooc;
public class Fing {
public static void main(String[] args) {
String ma="HelloWorld.java";
String You="laiya@imooc.com";
int in='.';
System.out.println("字符'.'出现在:"+ma.lastIndexOf(in));
String pr="java";
System.out.println(You.length());
if (in!=-1&&in!=1&&pr.equals("java")) {
System.out.println("java文件正确");
}else {
System.out.println("java文件无效");
}
int a1='@';
System.out.println(You.indexOf(a1));
int a2='.';
System.out.println(You.indexOf(a2));
if (a1!=-1&&a2>a1) {
System.out.println("邮政格式正确");
}else {
System.out.println("邮政格式不正确");
}}}字符'.'出现在:10
15
java文件正确
5
11
邮政格式不正确
