Java StreamTokenizer nextToken（）方法与示例

StreamTokenizer类nextToken()方法 (StreamTokenizer Class nextToken() method)

nextToken() method is available in java.io package.
nextToken()方法在java.io包中可用。
nextToken() method is used to parse the next token from the input stream of this StreamTokenizer and the type of the next token is returned in the ttype field.
nextToken()方法用于解析此StreamTokenizer的输入流中的下一个标记，并且下一个标记的类型在ttype字段中返回。
nextToken() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
nextToken()方法是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。
nextToken() method may throw an exception at the time of returning next token.
nextToken()方法在返回下一个令牌时可能会引发异常。

IOException: This exception may throw when getting any input/output error while performing.
IOException：在执行过程中遇到任何输入/输出错误时，可能引发此异常。

Syntax:

句法：

    Public int nextToken();

Parameter(s):

参数：

It does not accept any parameter.
它不接受任何参数。

Return value:

返回值：

The return type of the method is int, it gets the value of ttype field (i.e. type of the next token).

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

Example:

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();
}
}
}

Output

输出量

= 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