Java verifies the correctness of the mailbox format and whether the verification string is a number

Verify email format in Java

Import java. util. RegEx. matcher;
Import java. util. RegEx. pattern;

Public class registercheck {
/**
* Verify that the entered email format is correct.
* @ Param email
* @ Return is legal
*/
Public static Boolean emailformat (string email)
{
Boolean tag = true;
Final string pattern1 = "^ ([a-z0-9A-Z] + [-| \.]?) + [A-z0-9A-Z] @ ([a-z0-9A-Z] + (-[a-z0-9A-Z] + )? \.) + [A-Za-Z] {2,} $ ";
Final pattern = pattern. Compile (pattern1 );
Final matcher MAT = pattern. matcher (email );
If (! Mat. Find ()){
Tag = false;
}
Return tag;
}
}

Verify that the string is a number

 

There are four methods below. The third method is probably useful.

1. Use Java built-in functions
Public static Boolean isnumeric (string Str ){
For (INT I = Str. Length (); -- I> = 0 ;){
If (! Character. isdigit (Str. charat (I ))){
Return false;
}
}
Return true;
}

2. Regular Expression
Public static Boolean isnumeric (string Str ){
Pattern pattern = pattern. Compile ("[0-9] *");
Return Pattern. matcher (STR). Matches ();
}

3. Regular Expression Public static Boolean isnumeric (string Str ){
If (Str. Matches ("\ D *"){
Return true;
} Else {
Return false;
}
}
4. Use ASCII code
Public static Boolean isnumeric (string Str ){
For (INT I = Str. Length (); -- I> = 0 ;){
Int CHR = Str. charat (I );
If (CHR <48 | CHR> 57)
Return false;
}
Return true;
}