我正在寫一個初學者編碼類代碼時遇到生產我的電子郵件驗證項目的子麻煩。不尋找正則表達式,只是非常簡單的初學者級別的編碼。在java.lang.String.substring(字符串-1 : 異常線程 「main」 java.lang.StringIndexOutOfBoundsException prabhu_iastate.edu:字符串索引超出範圍Java的String指數超出範圍的電子郵件項目
package email;
import java.util.Scanner;
/**
* Input: An email address of your choosing
* Output: If the email is valid, return, "Valid" If invalid, return "Invalid."
* An input of "[email protected]" would return valid because of all the requirements an address should have is present
*/
public class EMail {
public static void main(String[] args) {
System.out.print("Enter an email address: ");//input prompt
String bad = "Email is invalid";//shows if email is invalid
String good = "Email is valid";//shows if email is valid
Scanner In = new Scanner(System.in);//Reads input from user
String email = In.next();//read the input into a String variable using In as the Scanner
int atIndex = email.indexOf('@');//shows location of '@' character
int lastDotIndex = email.lastIndexOf('.');//shows location of the last'.' in email String
int dotIndex = email.indexOf('.');//shows the location of the character of '.'
String location = email.substring(atIndex, -1);
if((atIndex == -1) ||(dotIndex == -1)){//If the input email does not have '@' or "." it is invalid
System.out.println(bad);
}
else if(atIndex == 0){//if the character'@' is the first character
System.out.println(bad);
}
else if(dotIndex == email.length()-1){//if the '.' is the last character the email is invalid
System.out.println(bad);
}
else if(lastDotIndex < atIndex){//if the last "." is before the '@' symbol the email is invalid
System.out.println(bad);
}
else if(email.lastIndexOf('.') < email.indexOf('.')){//if the first '.' is the last character the email is invalid
System.out.println(bad);
}
else if((location.length()== -1)|| location.length() <= 0){//If there is no string between the '@' char & the last '.'
System.out.println(bad);
}
else{
System.out.println(good);
System.out.println(location);
}
}
}
輸入電子郵件地址。 Java的:1960) 在email.EMail.main(EMail.java:23)
如果沒有一個@符號輸入電子郵件地址,我得到一個出界異常時,首先命名我的子在這裏,「字符串位置= email.substring(atIndex,-1);「繞過這個錯誤的任何方法?
不要描述你的異常,包括*確切*在你的問題整個堆棧跟蹤的文本。 – azurefrog