context.java~4~

《深入浅出设计模式》的完整源代码

package littlecompiler;
import java.util.*;
public class Context {
  private StringTokenizer tokenizer;
      private String currentToken;

      public Context(String text) {
          tokenizer = new StringTokenizer(text);
          nextToken();
      }

      public String nextToken() {
          if (tokenizer.hasMoreTokens()) {
              currentToken = tokenizer.nextToken();
          } else {
              currentToken = null;
          }
          return currentToken;
      }

      public String currentToken() {
          return currentToken;
      }

      public void skipToken(String token) {
          if (!token.equals(currentToken)) {
              System.err.println("Warning: " + token + " is expected, but " + currentToken + " is found.");
          }
          nextToken();
      }

      public int currentNumber() {
          int number = 0;
          try {
              number = Integer.parseInt(currentToken);
          } catch (NumberFormatException e) {
              System.err.println("Warning: " + e);
          }
          return number;
      }
}