Java extracts a simple instance of a number from a string _java

Give you a string that contains numbers, such as:

String s= "EERT343DFG56756DTRY66FGGG89DFGF";

So how do we extract the numbers? There are roughly the following methods, regular expressions, collection classes, and the methods provided by the string class.

1 The method provided by the String class:

Package test practice;
Import java.util.*;
public class Get_stringnum {


/**
 *2016.10.25
 *

/public static void main (string[] args) {
String str = "Love23next234csdn3423javaeye";
Str=str.trim ();
String str2= "";
if (str!= null &&! "". Equals (str)) {for
(int i=0;i<str.length (); i++) {
if (Str.charat (i) >=48 && str.charat (i) <= {
Str2+=str.charat (i);
}
}} System.out.println (STR2);
}

Output:

232343423

This method has an obvious disadvantage, only the number can be extracted together, can not be extracted separately. Of course also can improve, interested friends can try.

2 Regular Expressions

Import java.util.*;
Import Java.util.regex.Matcher;
Import Java.util.regex.Pattern;
public class Get_stringnum {


/**
 *2016.10.25
 *

/public static void main (string[] args) {
String a= " Love23next234csdn3423javaeye ";
String regex= "[^0-9]";  
Pattern p = pattern.compile (regEx);  
Matcher m = P.matcher (a);  
System.out.println (M.replaceall (""). Trim ());
}

Output:

232343423

Pattern, Matcher is the Java.util.regex software package in the two classes, the specific use of the API you can check. Similarly, you cannot extract numbers individually.

3 Collection Class Library

Import java.util.*;
Import Java.util.regex.Matcher;
Import Java.util.regex.Pattern;
public class Get_stringnum {


/**
 *2016.10.25
 *

/public static void main (string[] args) {
  String a= " Love23next234csdn3423javaeye ";
list<string> digitlist = new arraylist<string> ();
Pattern p = pattern.compile ("[^0-9]");
Matcher m = P.matcher (a);
String result = M.replaceall ("");
for (int i = 0; i < result.length (); i++) {
Digitlist.add (result.substring (i, i+1));
System.out.println (digitlist);

}

Output:

[2, 3, 2, 3, 4, 3, 4, 2, 3]

The same idea:

Import java.util.*;
Import Java.util.regex.Matcher;
Import Java.util.regex.Pattern;
public class Get_stringnum {


/**
 *2016.10.25
 *

/public static void main (string[] args) {
        String a= " Love23next234csdn3423javaeye ";
    list<string> ss = new arraylist<string> ();
    For (String sss:s.replaceall ("[^0-9]", ","). Split (",")) {
      if (sss.length () >0)
        Ss.add (SSS);
    }
    System.out.print (ss);


}

}

Output:

[2, 3, 2, 3, 4, 3, 4, 2, 3]

Obviously, we can extract the numbers separately using regular expressions.

There is also an answer that uses a lookup document to find the following:

/**
 * Obtains the number from the string literal * 

@param
 Text 

* @return/
 

publicstatic
 list<long>
 Getdigit (String text) { 

list<long>
 digitlist =new
 arraylist<long> ();
 

Pattern p=
 pattern.compile ("(\\d+)");
 

Matcher m=
 p.matcher (text); 

While
 (M.find ()) { 

String find=
 m.group (1). toString (); 

Digitlist.add (long.valueof (Find)); 

return
 digitlist; 

}

Two methods for judging the matching of regular expressions are as follows;

Determines whether a string is a numeric public 
boolean isdigit (String strnum) {return 
  strnum.matches ("[0-9]{1,}"); 
} 
 
Determines whether a string is a digital public 
boolean isdigit (string strnum) {pattern Pattern 
  = Pattern.compile ("[0-9]{1,}"); 
  Matcher Matcher = Pattern.matcher ((charsequence) strnum); 
  return matcher.matches (); 
} 
 
  Intercepts the digital public 
  String getnumbers (string content) {pattern pattern 
    = pattern.compile ("\\d+"); 
    Matcher Matcher = pattern.matcher (content); 
    while (Matcher.find ()) {return 
      matcher.group (0); 
    } 
    Return ""; 
  } 
 
Intercepts non-digital public 
String Splitnotnumber (string content) {pattern pattern 
  = pattern.compile ("\\d+"); 
  Matcher Matcher = pattern.matcher (content); 
  while (Matcher.find ()) {return 
    matcher.group (0); 
  } 
  Return ""; 
} 

The above is a small series of Java from the string to extract the number of simple examples of all the content, I hope that many support cloud Habitat Community ~