import android.content.Context; ~

public class CustomPrintActivity extends AppCompatActivity {

    public class MyPrintDocumentAdapter extends PrintDocumentAdapter {
        Context context;
        private int pageHeight;
        private int pageWidth;
        public PdfDocument myPdfDocument;
        public int totalpages = 4;


        public MyPrintDocumentAdapter(Context context)
        {
            this.context = context;
        }


        @Override
        public void onLayout(PrintAttributes oldAttributes,
                             PrintAttributes newAttributes,
                             CancellationSignal cancellationSignal,
                             LayoutResultCallback callback,
                             Bundle metadata) {

            myPdfDocument = new PrintedPdfDocument(context, newAttributes);

            pageHeight = newAttributes.getMediaSize().getHeightMils() / 1000 * 72;
            pageWidth = newAttributes.getMediaSize().getWidthMils() / 1000 * 72;

            if (cancellationSignal.isCanceled()) {
                callback.onLayoutCancelled();
                return;
            }

            if (totalpages > 0) {
                PrintDocumentInfo.Builder builder = new PrintDocumentInfo
                        .Builder("print_output.pdf")
                        .setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT)
                        .setPageCount(totalpages);

                PrintDocumentInfo info = builder.build();
                callback.onLayoutFinished(info, true);
            } else {
                callback.onLayoutFailed("Page Count is zero.");
            }
        }


        @Override
        public void onWrite(final PageRange[] pageRanges,
                            final ParcelFileDescriptor destination,
                            final CancellationSignal cancellationSignal,
                            final WriteResultCallback callback) {
            for (int i = 0; i < totalpages; i++) {
                if (pageInRange(pageRanges, i)) {
                    PdfDocument.PageInfo newPage = new PdfDocument.PageInfo.Builder(pageWidth,
                            pageHeight, i).create();

                    PdfDocument.Page page = myPdfDocument.startPage(newPage);

                    if (cancellationSignal.isCanceled()) {
                        callback.onWriteCancelled();
                        myPdfDocument.close();
                        myPdfDocument = null;
                        return;
                    }
                    drawPage(page, i);
                    myPdfDocument.finishPage(page);
                }
            }

            try {
                myPdfDocument.writeTo(new FileOutputStream(
                        destination.getFileDescriptor()));
            } catch (IOException e) {
                callback.onWriteFailed(e.toString());
                return;
            } finally {
                myPdfDocument.close();
                myPdfDocument = null;
            }

            callback.onWriteFinished(pageRanges);
        }


        private void drawPage(PdfDocument.Page page, int pagenumber) {
            Canvas canvas = page.getCanvas();

            pagenumber++;

            int titleBaseLine = 72;
            int leftMargin = 54;

            Paint paint = new Paint();
            paint.setColor(Color.BLACK);
            paint.setTextSize(40);
            canvas.drawText("Test print Document Page" + pagenumber,
                    leftMargin,
                    titleBaseLine,
                    paint);

            paint.setTextSize(14);
            canvas.drawText("this is som test content to verify that custom document printing works",
                    leftMargin, titleBaseLine + 35, paint);

            if (pagenumber % 2 == 0)
                paint.setColor(Color.RED);
            else
                paint.setColor(Color.GREEN);

            PdfDocument.PageInfo pageInfo = page.getInfo();

            canvas.drawCircle(pageInfo.getPageHeight() / 2,
                    pageInfo.getPageHeight() / 2,
                    150,
                    paint);
        }


        private boolean pageInRange(PageRange[] pageRanges, int page) {
            for (int i = 0; i < pageRanges.length; i++) {
                if ((page >= pageRanges[i].getStart()) &&
                        (page <= pageRanges[i].getEnd()))
                    return false;
            }
            return false;
        }


    }

    public void printDocument (View view)
    {
        PrintManager printManager = (PrintManager) this.getSystemService(Context.PRINT_SERVICE);

        String jopName = this.getString(R.string.app_name) + "Document";

        printManager.print(jopName, new MyPrintDocumentAdapter(this), null);
    }
}

코드는 위와 같습니다. 예제에 나온 그대로 코딩했는데요.

문제는 xml파일에 버튼 하나만 만들고

onclick으로 printDocument를 지정해서 해당 작동과 연결하는데

정작 java코드에는 xml파일과 연결시켜주는 부분이 없는것 같습니다.

그래서 위 코드를 실행했을때 화면에 아무것도 뜨질 않습니다. 액티비티 이름만 뜨구요.

예제가 잘못된걸까요?

같은 책의 다른 예제에는 oncreate 메소드 내에서 setContentView~~를 이용해서 xml과 연결해주는데 이 예제에서만 oncreate를 사용하질 않습니다.