Java - 如何清除文本文件而不删除它？
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Java - How to Clear a text file without deleting it?
提问by Kemosabe
I am wondering what the best way to clear a file is. I know that java automatically creates a file with
我想知道清除文件的最佳方法是什么。我知道java会自动创建一个文件
f = new Formatter("jibberish.txt");
s = new Scanner("jibberish.txt");
if none already exists. But what if one exists and I want to clear it every time I run the program? That is what I am wondering: to say it again how do I clear a file that already exists to just be blank? Here is what I was thinking:
如果不存在。但是如果一个存在并且我想在每次运行程序时清除它怎么办？这就是我想知道的：再说一遍，我如何清除已存在的文件以使其成为空白？这是我的想法：
public void clearFile(){
//go through and do this every time in order to delete previous crap
while(s.hasNext()){
f.format(" ");
}
}
采纳答案by Ankur Anand
If you want to clear the file without deleting may be you can workaround this
如果您想清除文件而不删除可能是您可以解决此问题
public static void clearTheFile() {
FileWriter fwOb = new FileWriter("FileName", false);
PrintWriter pwOb = new PrintWriter(fwOb, false);
pwOb.flush();
pwOb.close();
fwOb.close();
}
Edit: It throws exception so need to catch the exceptions
编辑：它抛出异常所以需要捕捉异常
回答by CKing
You could delete the file and create it again instead of doing a lot of io.
您可以删除该文件并重新创建它，而不是执行大量 io。
if(file.delete()){
file.createNewFile();
}else{
//throw an exception indicating that the file could not be cleared
}
Alternately, you could just overwrite the contents of the file in one go as explained in the other answers :
或者，您可以一次覆盖文件的内容，如其他答案中所述：
PrintWriter writer = new PrintWriter(file);
writer.print("");
writer.close();
Also, you are using the constructor from Scannerthat takes a Stringargument. This constructor will not read from a file but use the Stringargument as the text to be scanned. You should first created a file handle and then pass it to the Scannerconstructor :
此外，您正在使用Scanner带有String参数的构造函数。此构造函数不会从文件中读取，而是使用String参数作为要扫描的文本。您应该首先创建一个文件句柄，然后将其传递给Scanner构造函数：
File file = new File("jibberish.txt");
Scanner scanner = new Scanner(file);
回答by Sarath Kumar Sivan
You can just print an empty string into the file.
您可以将空字符串打印到文件中。
PrintWriter writer = new PrintWriter(file);
writer.print("");
writer.close();
回答by TheCoder
Best I could think of is :
我能想到的最好的是：
Files.newBufferedWriter(pathObject , StandardOpenOption.TRUNCATE_EXISTING);
and
和
Files.newInputStream(pathObject , StandardOpenOption.TRUNCATE_EXISTING);
In both the cases if the file specified in pathObject is writable, then that file will be truncated. No need to call write() function. Above code is sufficient to empty/truncate a file.This is new in java 8.
在这两种情况下，如果 pathObject 中指定的文件是可写的，那么该文件将被截断。无需调用 write() 函数。上面的代码足以清空/截断文件。这是 Java 8 中的新功能。
Hope it Helps
希望能帮助到你
