java codeformatter throwing NullPointerEception

Question

I have one java code to format the another java code programaticlly. The code is working fine for simple java code.But when i am introducing commnent in my input java code (input taken as String code) then in the following line textEdit is returned as null which is causing nullpointerexception in next steps.

TextEdit textEdit = codeFormatter.format(CodeFormatter.K_UNKNOWN , code, 0, code.length(), 0, null);


import org.eclipse.jdt.core.ToolFactory;
import org.eclipse.jdt.core.formatter.CodeFormatter;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.Document;
import org.eclipse.jface.text.IDocument;
import org.eclipse.text.edits.MalformedTreeException;
import org.eclipse.text.edits.TextEdit;

public class FormatCode {

    public static void main(String[] args) {
        String code = "public class TestFormatter{public static void main(String[] args){for(i=0;i<10;i++){i=i+2;\\abc"+"}System.out.println(\"Hello World\");}}";
        CodeFormatter codeFormatter = ToolFactory.createCodeFormatter(null);

        TextEdit textEdit = codeFormatter.format(CodeFormatter.K_UNKNOWN , code, 0, code.length(), 0, null);
        IDocument doc = new Document(code);
        try {
            textEdit.apply(doc);
            System.out.println(doc.get());
        } catch (MalformedTreeException e) {
            e.printStackTrace();
        } catch (BadLocationException e) {
            e.printStackTrace();
        }
    }
}

Any hint to solve this issue.

Answer 1

Use commenting in new line. The // comment is beeing used in one line so your code is like that.

In other words, to solve this issue, create /* comments instead.

Answer 2

This part {i=i+2;\\abc" should be {i=i+2;//abc\n" You need to use // for commenting not \ also you should create a newline after the comment otherwise the rest of your code will be on the same line and be commented out.

Answer 3

Basically, you got a null from codeFormatter.format, because, as the documentation says:

It returns null if the given string cannot be formatted.

As your program cannot be properly parsed (because of the comment issue), it can also not be formatted. You should check for a returned null from format() if there is any possibility that the texts it will be processing are not correct and formattable.