使用Java删除换行

Question

I have a text file with a mix of newlines (CR/LF or \\r\\f or "\\n") and formfeeds (LF or \\f ) in a tab \\t delimited file. The newlines appear as the expected, "\\n" but the formfeeds are also used as internal field delimiters. Example:

COL_1   COL_2   COL_3    COL_4
1       A\fB    C\fD     2    

Using Java I was able to remove the formfeeds only after I set line.separator to \\r - for CR/LF or \\r\\f and then reading in the file using the FileReader.read() checking for '\\n' :

private void fixMe() throws Exception{

  FileReader in  = new FileReader("C:\\somefile.txt"); 
  FileReader out = new FileReader("C:\\someotherfile.txt"); 

  Syetem.setProperty("line.separator","\r");

  try {
    int c;
    while (( c = in.read()) != -1 ) {
        if ( c != '\n' ) {
             out.write(c);
        }
    }
  }
  ...

It appears that in.read has a default setting to read "\\n" as two characters. I can remove \\f but now I'll have to write another method to change \\r to a "\\n" and reset line.separator as part of the method. Is there a better way to do this? I want to use Scanner, but the solution points at resetting the line.separator setting again which I want to avoid.

Answer 1

Better way to read all file content, then remove "\\n and \\r\\n and \\f", after save where you want.

See example:

String content = new String(Files.readAllBytes(Paths.get("path-to-file")));
String processedContent = content.replaceAll("\\n|\\r\\n|\\f", "");

Answer 2

According to your question it seems like you want to skip Line Feed '\\f' in the file without skipping if it is CRLF \\r\\f, so keeping track of last character read might solve your issue.

private void fixMe() throws Exception{

  FileReader in  = new FileReader("C:\\somefile.txt"); 
  FileReader out = new FileReader("C:\\someotherfile.txt"); 

//Character 10 'LF' or '\f' and 13 'CR' or '\r'
  try {
    int c;
    int prevCharRead = 0;
    while ((c = in.read()) != -1 ) {
        if(c==10 && prevCharRead!=13){
        //it's a line feed LF '\f' without the occurrence of CR '\r' before it, skip it or implement whatever logic you want.  
        }else  
           out.write(c);

        prevCharRead = c;
    }
  }
  ...