Java中的正则表达式仅允许使用字母数字输入数据

Question

I need the regex expression which would accept only alphanumeric data.

Say for eg: ABC12DG - should allow this

if input data is 123000 - should not allow as it is only numeric.

I have tried this

say a is a string which contains the input data

then a.matches("^[a-zA-Z0-9]+$") this allows both the first and second input as above

I only want it to allow the alphanumeric input , not just numeric or alphabets How to do that

Answer 1

Use negative lookahead or alternation operator.

a.matches("^(?![A-Za-z]+$)(?!\\d+$)[a-zA-Z0-9]+$");

• (?![A-Za-z]+$) asserts that the match won't contain only alphabets.
• (?!\\\\d+$) asserts that the match won't contain only digits.
• [a-zA-Z0-9]+ Matches one or more alphanumeric characters.

or

a.matches("^[a-zA-Z0-9]*(?:[a-zA-Z]\\d|\\d[a-zA-Z])[a-zA-Z0-9]*$");

Answer 2

You can try this Regex for your text:

    String reg = "\\p{Alpha}+\\d+";
    String str1 = "It &* is %$ now OK 2015";
    String str2 = "ItisnowOK2015";
    String str3 = "888";
    String str4 = "aaa";
    System.out.println("str1 = "+str1.matches(reg));
    System.out.println("str2 = "+str2.matches(reg));
    System.out.println("str3 = "+str3.matches(reg));
    System.out.println("str4 = "+str4.matches(reg));

And is the result:

str1 = false
str2 = true
str3 = false
str4 = false