Question

I have a program that reads in lines from a file (with two lines) using a while loop (condition is bufferedReader.readLine()!=null), assigns myJSONObject a JSON read from the file, then I have an if statment (if(bufferedReader.readLine()!=null&&!bufferedReader.readline.matches(DELETE_REGEX)) and if that’s true (i.e. if the line we read is not null, and we don’t match a regex) then perform some function on the JSON which should append that new JSON to a file.

I have this in some try-catch blocks. It looks a little like so:

try{
    openFiles;
    while(buff.readLine()!=null){
          try {
              instatiateAndUseJSONParser;
              if(bufferedReader.readLine()!=null
                    &&!bufferedReader.readline.matches(DELETE_REGEX)) 
              {doSomeStuff;}
              else
              {continue;}
          } catch (AllTheExceptions e){e.printStackTrace}
     }
     closeFiles;
}catch(SomeMoreExceptions e){e.printStackTrace}

When I run this is gets to the iff statement, and then terminates with exit value:0 (program closed as normal)

Why is this? It doesn’t get anywhere near the ‘continue’ or a catch block.

If I remove the second line I get a NullPointerException due to line 50 of String Reader, but I’m not using StringReader (I’ve tried importing it, but eclipse yellow-underlines it and this changes nothing). When debugging, it pops up a tab for StringReader.<init>(String) line: 50 and just says ‘Source not found’.

I’m pretty new to Java, so I don’t really have a clue what’s happening. Any help would be appreciated in clearing this up.

Thanks!

Answer 1

Every time readLine() is called, it reads a new line. You can thus read 3 lines per iteration in your current code. You should assign the result of the first call to a variable, and use this variable:

String line = null;
while ((line = buff.readLine()) !=null) {
    try {
        instatiateAndUseJSONParser;
        if (line.matches(DELETE_REGEX)) {
            doSomeStuff;
        }
    } 
    catch (AllTheExceptions e){
        throw new RuntimeException(e);
    }
}

You should also avoid swallowing exceptions.