问题描述
基本上我想知道PrintWriter是否是Buffered Writer。
我见过代码如 PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter(file)));
但是来自此的Javadoc 一>:
Basically I would like to know whether or not the PrintWriter is a Buffered Writer.I have seen code like PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter(file)));
However from this javadoc:
底线:我认为PrintWriter是缓冲的,因为javadoc有点提到它(见报价),如果我不刷新PrintWriter,它就不会被打印出来。
你确认我的论文吗?在这种情况下,为什么会有一些代码如下:
PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter(file)));
遗留代码?
Bottom line: I think that PrintWriter is buffered since the javadoc "kind of mention it" (see the quote) and if I don't flush a PrintWriter it does not get printed.Do you confirm my thesis? In that case why there is some code that goes like:PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter(file)));
legacy code?
提前致谢。
推荐答案
从技术上讲,它不是 BufferedWriter
。它直接扩展 Writer
。也就是说,似乎可以使用 BufferedWriter
,具体取决于您调用的构造函数。例如,查看传递 String
的构造函数:
Technically, it is not a BufferedWriter
. It directly extends Writer
. That said, it seems like it can use a BufferedWriter
depending on the constructor you call. For exampe look at the constructor that passes in a String
:
public PrintWriter(String fileName) throws FileNotFoundException {
this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName))),
false);
}
另外,你没有使用你链接的javadoc的构造函数至。你已经使用了带 Writer
的构造函数。那个似乎没有使用 BufferedWriter
。这是它的源代码:
Also, you're not using the constructor for the javadoc you've linked to. You've used the constructor that takes a Writer
. That one does not seem to use a BufferedWriter
. This is its source code:
/**
* Creates a new PrintWriter, without automatic line flushing.
*
* @param out A character-output stream
*/
public PrintWriter (Writer out) {
this(out, false);
}
/**
* Creates a new PrintWriter.
*
* @param out A character-output stream
* @param autoFlush A boolean; if true, the <tt>println</tt>,
* <tt>printf</tt>, or <tt>format</tt> methods will
* flush the output buffer
*/
public PrintWriter(Writer out,
boolean autoFlush) {
super(out);
this.out = out;
this.autoFlush = autoFlush;
lineSeparator = java.security.AccessController.doPrivileged(
new sun.security.action.GetPropertyAction("line.separator"));
}
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