Java StreamTokenizer slashSlashComments()用法及代码示例

StreamTokenizer类slashSlashComments()方法

• slashSlashComments() 方法可在java.io包。
• slashSlashComments() 方法用于标识此 StreamTokenizer 是否识别双斜杠注释(C++ 类型注释)。当布尔变量设置为 true 时，表示此 StreamTokenizer 识别双斜线注释，否则不会特别使用双斜线注释。
• slashSlashComments() 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。
• slashSlashComments() 方法在识别双斜线注释时不抛出异常。

用法:

    Public void slashSlashComments(boolean status);

参数：

• boolean status– 当它识别并避免双斜杠注释(即基于 C++ 的注释)时，此参数设置为 true。

返回值：

该方法的返回类型是void，它什么都不返回。

例：

// Java program to demonstrate the example 
// of void slashSlashComments(boolean status)
// method of StreamTokenizer

import java.io.*;

public class slashSlashComments {
    public static void main(String[] args) {
        String str = "Hi, This is \n 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);

            // By using slashSlashComments() method is to
            // set comments when boolean set to true and
            // when it encounters '//' in str
            st.slashSlashComments(true);

            // 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

word:BHi
, Found.
word:This
word:is
word:a
word:mathematical
word:expression
:Found.
number:2.0
* Found.
number:4.0
= Found.
number:8.0
End of File Found