Java StreamTokenizer nextToken()用法及代码示例

StreamTokenizer类nextToken()方法

• nextToken() 方法可在java.io包。
• nextToken() 方法用于解析此 StreamTokenizer 的输入流中的下一个标记，并在 ttype 字段中返回下一个标记的类型。
• nextToken() 方法是一个非静态方法，它只能通过类对象访问，如果我们尝试使用类名访问方法，那么我们将得到一个错误。
• nextToken() 方法可能在返回下一个令牌时抛出异常。
  IOException：在执行过程中遇到任何输入/输出错误时可能会抛出此异常。

用法:

    Public int nextToken();

参数：

• 它不接受任何参数。

返回值：

该方法的返回类型是int，它获取 ttype 字段的值(即下一个标记的类型)。

例：

// Java program to demonstrate the example 
// of int nextToken() method of StreamTokenizer

import java.io.*;

public class NextToken {
    public static void main(String[] args) {
        String str = "Hi, This is a mathematical expression:\n" +
            " 2 * 4 = 8" + "8 + 5 = 13";

        try {
            // Instantiates FileOutputStream  and ObjectOutputStream 
            FileOutputStream fos_stm = new FileOutputStream("D:\\includehelp.txt");
            ObjectOutputStream obj_out_stm = new ObjectOutputStream(fos_stm);

            // By using writeUTF() method is to
            // write the given string in the file
            obj_out_stm.writeUTF(str);
            obj_out_stm.flush();

            // Instantiates FileOutputStream  and ObjectOutputStream 
            ObjectInputStream obj_in_stm = new ObjectInputStream(new FileInputStream("D:\\includehelp.txt"));

            // Instantiates StreamTokenizer and Reader
            Reader reader = new BufferedReader(new InputStreamReader(obj_in_stm));
            StreamTokenizer st = new StreamTokenizer(reader);

            // Here, we are considering initially 
            // file is not empty
            boolean end_of_file = false;

            while (!end_of_file) {
                // By using nextToken() method is to
                // parse the next token from the stream
                int token = st.nextToken();

                switch (token) {
                    case StreamTokenizer.TT_EOF:
                        System.out.println("End of File Found");
                        end_of_file = true;
                        break;

                    case StreamTokenizer.TT_EOL:
                        System.out.println("End of Line Found");
                        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 + " Found.");
                }
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

输出

= Found.
word:Hi
, Found.
word:This
word:is
word:a
word:mathematical
word:expression
:Found.
number:2.0
* Found.
number:4.0
= Found.
number:88.0
+ Found.
number:5.0
= Found.
number:13.0
End of File Found