Java.io.StreamTokenizer.nextToken() 方法

描述

java.io.StreamTokenizer.nextToken() 方法分析从标记生成器的输入流中的下一个令牌。下一个标记的类型在 ttype 字段中返回。关于令牌的附加信息可能在此令牌生成器的 nval 字段或 sval 字段中。此类的典型客户端首先设置语法表，然后在循环中调用 nextToken 来解析连续的标记，直到返回 TT_EOF。

声明

以下是java.io.StreamTokenizer.nextToken()方法的声明。

 public int nextToken()

参数

N/A

返回值

此方法返回 ttype 字段的值。

异常

IOException - 如果发生 I/O 错误。

例子

以下示例显示java.io.StreamTokenizer.nextToken()方法的用法。

 
package com.jc2182;

import java.io.*;

public class StreamTokenizerDemo {
   public static void main(String[] args) {
      String text = "Hello. This is a text \n that will be split "
         + "into tokens. 1 + 1 = 2";
         
      try {
         // create a new file with an ObjectOutputStream
         FileOutputStream out = new FileOutputStream("test.txt");
         ObjectOutputStream oout = new ObjectOutputStream(out);

         // write something in the file
         oout.writeUTF(text);
         oout.flush();

         // create an ObjectInputStream for the file we created before
         ObjectInputStream ois = new ObjectInputStream(new FileInputStream("test.txt"));

         // create a new tokenizer
         Reader r = new BufferedReader(new InputStreamReader(ois));
         StreamTokenizer st = new StreamTokenizer(r);

         // print the stream tokens
         boolean eof = false;
         
         do {
            int token = st.nextToken();
            
            switch (token) {
               case StreamTokenizer.TT_EOF:
                  System.out.println("End of File encountered.");
                  eof = true;
                  break;
                  
               case StreamTokenizer.TT_EOL:
                  System.out.println("End of Line encountered.");
                  break;
                  
               case StreamTokenizer.TT_WORD:
                  System.out.println("Word: " + st.sval);
                  break;
                  
               case StreamTokenizer.TT_NUMBER:
                  System.out.println("Number: " + st.nval);
                  break;
                  
               default:
                  System.out.println((char) token + " encountered.");
                  
                  if (token == '!') {
                     eof = true;
                  }
            }
         } while (!eof);

      } catch (Exception ex) {
         ex.printStackTrace();
      }
   }
}

让我们编译并运行以上程序，这将产生以下结果-

 
Word: Hello.
Word: This
Word: is
Word: a
Word: text
Word: that
Word: will
Word: be
Word: split
Word: into
Word: tokens.
Number: 1.0
+ encountered.
Number: 1.0
= encountered.
Number: 2.0
End of File encountered.