Java StreamTokenizer whitespaceChars()用法及代码示例

StreamTokenizer类whitespaceChars()方法

• whitespaceChars() 方法可在java.io包。
• whitespaceChars() 方法用于表示位于给定范围(st[start], en[end])内的所有字符都是空白字符。空白字符仅用于分隔输入流中的标记。
• whitespaceChars() 方法接受两个参数，并且两个参数都是 “int” 类型。
• whitespaceChars() 方法表示空白字符时不抛出异常。

用法:

    public void whitespaceChars(int st, int en);

参数：

• int st- 表示给定范围的起始端点。
• int en- 表示给定范围的结束端点。

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 whitespaceChars(int st, int en) method
// of StreamTokenizer

import java.io.*;

public class WhiteSpaceChars {
    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 whitespaceChars() method is to
            // represent all the chars lies in between 
            // (e,s) are whitespace chars
            st.whitespaceChars('e', 's');


            // 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:H
, Found.
word:T
word:a
word:at
word:at
word:ca
word:x
:Found.
number:2.0
* Found.
number:4.0
= Found.
number:8.0
number:8.0
+ Found.
number:5.0
= Found.
number:13.0
End of File Found