Added string tokenizer in java (#184)

* Added string tokenizer in java

* fix typos

* Update Readme change line index from 4 to 5

strings/README.md

@@ -24,6 +24,7 @@
 2. [All subsequences](java/sequence.java)
 3. [KMP String Searching](java/kmp.cpp)
 4. [Rabin Karp String Searching](java/rabin-karp.cpp)
+5. [String Tokenizer](java/tokenizer.java)
 
 ### Python
 

strings/java/tokenizer.java

@@ -0,0 +1,96 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public class tokenizer{
+
+    public static boolean charIsDelimiter(char c, char [] delimiters){
+        //verrify if a character is a delimiter
+        for(char d: delimiters)
+            if(c == d) return true;
+        
+        return false;
+    }
+
+    public static List<String> tokenize(String str, char... delimiters){
+        //by default the delimiter is white space ' '
+        if(delimiters.length <= 0) delimiters = new char [] {' '};
+
+        List<String> tokens = new ArrayList<String>();
+		String token  = "";
+
+		for(int i = 0; i < str.length(); i++) {
+			char pos = str.charAt(i);
+
+			if(!charIsDelimiter(pos, delimiters)) {
+                //if the character is not a delimiter add it into the current token
+				token += pos;
+			}else {
+                //avoid an empty token before adding to the list
+				if(!token.equals(""))
+					tokens.add(token);
+				
+                token = "";
+			}
+		}
+
+        //add the last token to the list
+		tokens.add(token);
+
+		return tokens;
+    }
+
+    public static void printTokens(List<String> tokens){
+        if(tokens == null) return;
+
+        System.out.print("[ ");
+        for(String token : tokens){
+            System.out.print("'" + token + "', ");
+        }
+        System.out.println("]");
+    }
+
+    public static void main(String  [] args){
+        String myString = "Hello     I like pasta & pizza--hut";
+
+        System.out.println("myString = '" + myString + "'");
+
+        System.out.print("\ntokenize(myString) = ");
+        printTokens(tokenize(myString));
+
+        System.out.print("\ntokenize(myString, ' ', 'z') = ");
+        printTokens(tokenize(myString, ' ', 'z'));
+
+        System.out.print("\ntokenize(myString, 'p','l', 'u') = ");
+        printTokens(tokenize(myString, 'p','l', 'u'));
+
+        System.out.print("\ntokenize(myString, ' ', '&', '-') = ");
+        printTokens(tokenize(myString, ' ', '&', '-'));
+    }
+}
+
+/*
+    to call the function:
+        tokenize(str, delimiters)
+        str is a text
+        delimiters is a list of char which is by default white space : ' '
+        example: 
+            tokenize("hello world") = tokenize("hello world", ' ') = [ 'hello', 'world' ]
+            tokenize("hello world", ' ', 'l') = [ 'he', 'o', 'wor', 'd' ]
+
+
+    to run this file:
+        javac tokenizer.java
+        java tokenizer
+
+    result:
+        myString = 'Hello     I like pasta & pizza--hut'
+
+        tokenize(myString) = [ 'Hello', 'I', 'like', 'pasta', '&', 'pizza--hut', ]
+
+        tokenize(myString, ' ', 'z') = [ 'Hello', 'I', 'like', 'pasta', '&', 'pi', 'a--hut', ]
+
+        tokenize(myString, 'p','l', 'u') = [ 'He', 'o     I ', 'ike ', 'asta & ', 'izza--h', 't', ]
+
+        tokenize(myString, ' ', '&', '-') = [ 'Hello', 'I', 'like', 'pasta', 'pizza', 'hut', ]
+            
+*/