java - how to check positive integer in a string and remove the space in between -

i used below method validate whether string contains integer numbers, , return using "parsephone" method. such program unable check whether there whitespace in between string format such "09213 2321". , output string space removed. besides, there better way combine these 2 methods one!?

public static string parsephone(string phone) {     if(phone==null) return null;     string s = phone.trim();      if(s.matches("^[0-9]+$"))     {         while(s.startswith("0")&& s.length()>1)         {             s = s.substring(1);         }         if(s.length()>=3) return s;     }     return null; }  public static boolean phonevalidation(string phone) {     if(phone == null) return false;     string string = phone.trim();      if(string.matches("^[0-9]+$"))     {         while(string.startswith("0")&& string.length()>1)         {             string = string.substring(1);         }         if(string.length()>=3) return true;     }     return false;  } 

try this:

public static string parsephone(string phone) {     if(phone==null) return null;     string s = phone.trim().replaceall("\\s","");      //the replaceall remove whitespaces      if(s.matches("^[0-9]+$"))     {          while(s.startswith("0")&& s.length()>1)         {             s = s.substring(1);         }          if(s.length()>=3) return s;     }  return null;  }  public static boolean phonevalidation(string phone) {     return parsephone(phone) != null; }