Java StreamTokenizer slashSlashComments()用法及代碼示例

StreamTokenizer類slashSlashComments()方法

• slashSlashComments() 方法可在java.io包。
• slashSlashComments() 方法用於標識此 StreamTokenizer 是否識別雙斜杠注釋(C++ 類型注釋)。當布爾變量設置為 true 時，表示此 StreamTokenizer 識別雙斜線注釋，否則不會特別使用雙斜線注釋。
• slashSlashComments() 方法是一個非靜態方法，它隻能通過類對象訪問，如果我們嘗試使用類名訪問方法，那麽我們將得到一個錯誤。
• slashSlashComments() 方法在識別雙斜線注釋時不拋出異常。

用法:

    Public void slashSlashComments(boolean status);

參數：

• boolean status– 當它識別並避免雙斜杠注釋(即基於 C++ 的注釋)時，此參數設置為 true。

返回值：

該方法的返回類型是void，它什麽都不返回。

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();
        }
    }
}

輸出

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