How to use Python to count comment line in a java source code?

Question

This is my code to count blank lines ,source code lines and total lines and comment lines. I use to check if there is '//' in a line to check if it is a comment line but I know it is wrong. Because '/ ... /' can form a comment block. How to count the number of lines in a comment block?

def FileLineCount(self,filename):
    (filepath,tempfilename) = os.path.split(filename);
    (shotname,extension) = os.path.splitext(tempfilename);
    if extension == '.java' : # file type 
        file = open(filename);
        self.sourceFileCount += 1;
        allLines = file.readlines();
        file.close();

        lineCount    = 0;
        commentCount = 0;
        blankCount   = 0;
        codeCount    = 0;
        for eachLine in allLines:
            if eachLine != " " :
                eachLine = eachLine.replace(" ",""); #remove space    #remove tabIndent
                if  eachLine.find('//') == 0 :  #LINECOMMENT 
                    commentCount += 1;
                else :
                    if eachLine == "":
                        blankCount += 1;
                    else :
                        codeCount += 1;
            lineCount = lineCount + 1;
        self.all += lineCount;
        self.allComment += commentCount;
        self.allBlank += blankCount;
        self.allSource += codeCount;
        print filename;
        print '           Total      :',lineCount ;
        print '           Comment    :',commentCount;
        print '           Blank      :',blankCount;
        print '           Source     :',codeCount;

Answer 1

There are problems with your code eg you can't just remove all whitespaces (you might consider /{whitespace}/ a comment). I'm not gonna provide actual code but this should give you a rough idea.

for each line of code  
1. Remove all white space from the beginning (left trimming).  
2. If mode is not multi-line and the line contains `//` increment counter.  
3. else if mode is not multi-line and the line contains `/*` go to multi-line mode.  
4. else if mode is multi-line  
           increment coutner
           if line contains `*/` exit multi-line mode

The conditions could be simplified, but I think you can get it to work.