Android如何強制給定的字符串是字母數字或不是

Question

我試過這段代碼。它不能正常工作..

String myString = "343DFDFD"; // "FDFS343434" 
System.out.println(myString.matches("[A-Za-z0-9]+")); // false coming 

注：我想上面的字母數字輸出爲true

Answer 1

修改正則表達式爲：

String myString = "343DFDFD"; // "FDFS343434" 
System.out.println(myString.matches("^.*[^a-zA-Z0-9 ].*$")); // false coming 

Answer 2

Use it: 

public boolean isAlphanumeric(String str) { 
     for (int i=0; i<str.length(); i++) { 
      char c = str.charAt(i); 
      if (!Character.isDigit(c) && !Character.isLetter(c)) 
       return false; 
     } 

     return true; 
    }