java 从包含特定字符的字符串中删除行
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Removing lines from a string containing certain character
提问by Serpace
I am working a Java project to read a java class and extract all DOC comments into an HTML file. I am having trouble cleaning a string of the lines I don't need.
我正在处理一个 Java 项目来读取一个 Java 类并将所有 DOC 注释提取到一个 HTML 文件中。我在清理一串不需要的行时遇到了麻烦。
Lets say I have a string such as:
假设我有一个字符串，例如：
"/**
* Bla bla
*bla bla
*bla bla
*/
CODE
CODE
CODE
/**
* Bla bla
*bla bla
*bla bla
*/ "
I want to remove all the lines not starting with *.
我想删除所有不以*.
Is there any way I can do that?
有什么办法可以做到吗？
回答by ankh-morpork
First, you should split your Stringinto a String[]on line breaks using String.split(String). Line breaks are usually '\n'but to be safe, you can get the system line separator using System.getProperty("line.separator");.
首先，你应该将拆分String成String[]使用换行符String.split(String)。换行符通常是'\n'为了安全起见，您可以使用System.getProperty("line.separator");.
The code for splitting the Stringinto a String[]on line breaks can now be
用于将 拆分String为String[]换行符的代码现在可以是
String[] lines = originalString.split(System.getProperty("line.separator"));
With the String split into lines, you can now check if each line starts with *using String.startsWith(String prefix), then make it an empty string if it does.
将 String 拆分成行后，您现在可以检查每行是否以*using开头，如果是String.startsWith(String prefix)，则将其设为空字符串。
for(int i=0;i<lines.length;i++){
if(lines[i].startsWith("*")){
lines[i]="";
}
}
Now all you have left to do is to combine your String[]back into a single String
现在你剩下要做的就是将你的String[]背部组合成一个单一的String
StringBuilder finalStringBuilder= new StringBuilder("");
for(String s:lines){
if(!s.equals("")){
finalStringBuilder.append(s).append(System.getProperty("line.separator"));
}
}
String finalString = finalStringBuilder.toString();
回答by Dermot Blair
Yes Java's String class has a startsWith() method that returns a boolean. You can iterate through each line in the file and check if each line starts with "*" and if it does delete it.
是的，Java 的 String 类有一个可以返回布尔值的 startsWith() 方法。您可以遍历文件中的每一行并检查每一行是否以“*”开头以及是否将其删除。
Try this:
试试这个：
File inputFile = new File("myFile.txt");
File tempFile = new File("myTempFile.txt");
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String linesToRemoveStartsWith = "*";
String currentLine;
while((currentLine = reader.readLine()) != null) {
// trim newline when comparing with lineToRemove
String trimmedLine = currentLine.trim();
if(!trimmedLine.startsWith(linesToRemoveStartsWith )) continue;
writer.write(currentLine + System.getProperty("line.separator"));
}
writer.close();
reader.close();
boolean successful = tempFile.renameTo(inputFile);
回答by mashaned
As far as I remember, you cannot delete lines from the text documents in-place in Java. So, you would have to copy the needed lines into a new file. Or, if you need to output the same file, just changed, you could read the data into memory, delete the file, create a new one with the same name and only output the needed lines. Although, frankly, for me it seems a bit silly.
据我所知，您不能在 Java 中就地删除文本文档中的行。因此，您必须将所需的行复制到新文件中。或者，如果您需要输出相同的文件，只是更改，您可以将数据读入内存，删除文件，创建一个同名的新文件，只输出所需的行。虽然，坦率地说，对我来说这似乎有点傻。
