I think this is a praser, I hope.

fuck_this_praser.java

//FuckTokenStream
import java.io.*;

public class FuckTokenStream implements TokenStream {

    private BufferedReader br;
    private int pos = 0;
    private char[] cache;

    FuckTokenStream(InputStream is) {
        this.br = new BufferedReader(new InputStreamReader(is));
        getStmtBuf(br);
    }

    private void getStmtBuf(BufferedReader br) {
        try {
            cache = br.readLine().toCharArray();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public Token getToken() throws IOException {
        if (pos >= cache.length) return new Token(Token.TokenType.NONE, null);
        while (cache[pos] == ' ') consumeToken();
        Token tmp = matcher(cache[pos]);
        if (tmp.tokenType != Token.TokenType.INT) {
            return tmp;
        } else {
            Token ret = tmp;
            int buf = (int) ret.value;
            int off = 1;
            while ((pos + off) < cache.length &&
                    (tmp = matcher(cache[pos + off])) != null &&
                    tmp.tokenType == Token.TokenType.INT) {
                buf *= 10;
                buf += (int) tmp.value;
                ret = new Token(Token.TokenType.INT, buf);
                off++;
            }
            pos += off - 1;
            return ret;
        }
    }

    @Override
    public void consumeToken() {
        pos++;
    }

    private Token matcher(char var) throws IOException {
        switch (var) {
            case '(':
                return new Token(Token.TokenType.LPAR, var);
            case ')':
                return new Token(Token.TokenType.RPAR, var);
            case '+':
                return new Token(Token.TokenType.PLUS, var);
            case '-':
                return new Token(Token.TokenType.MINUS, var);
            case '*':
                return new Token(Token.TokenType.MULT, var);
            case '/':
                return new Token(Token.TokenType.DIV, var);
            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7':
            case '8':
            case '9':
            case '0':
                return new Token(Token.TokenType.INT, Character.getNumericValue(var));
            case '\n':
                return new Token(Token.TokenType.NONE, var);
            default:
                return null;
        }
    }
}

//Token
class Token {
    public enum TokenType {
        LPAR, RPAR,
        PLUS,
        MINUS,
        MULT,
        DIV,
        INT,
        NONE,
    }
    TokenType tokenType;
    Object value;

    Token(TokenType tt, Object v) {
        this.tokenType = tt;
        this.value = v;
    }
}

//main
public class Main {
    public static void main(String[] args) {
        TokenStream ts = new FuckTokenStream(System.in);
        try {
            Token tmp;
            while ((tmp = ts.getToken()).tokenType != Token.TokenType.NONE) {
                if (tmp.value != null) {
                    System.out.println(tmp.tokenType + " " + tmp.value);
                }
                ts.consumeToken();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

        System.exit(0);
    }
}