Thread: Can someone tell me how to convert this C++ code to java? (just 50 lines)

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
 
using namespace cv;
using namespace std;
 
int main( int argc, char** argv )
{
 Mat src; Mat src_gray;
 src = imread( "airplane1.jpg", 1 );
 resize(src, src, Size(640,480), 0, 0, INTER_CUBIC);
 cvtColor( src, src_gray, CV_BGR2GRAY );
 blur( src_gray, src_gray, Size(3,3) ); 
 namedWindow( "Source", CV_WINDOW_AUTOSIZE );
 imshow( "Source", src );
 
 
 
 // Convex Hull implementation
 Mat src_copy = src.clone();
 Mat threshold_output;
 vector<vector<Point> > contours;
 vector<Vec4i> hierarchy;
 
 // Find contours
 threshold( src_gray, threshold_output, 200, 255, THRESH_BINARY );
 findContours( threshold_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );
 
 // Find the convex hull object for each contour
 vector<vector<Point> >hull( contours.size() );
 for( int i = 0; i < contours.size(); i++ )
 {  convexHull( Mat(contours[i]), hull[i], false ); }
 
 // Draw contours + hull results
 RNG rng;
 Mat drawing = Mat::zeros( threshold_output.size(), CV_8UC3 );
 for( int i = 0; i< contours.size(); i++ )
 {
  Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );
  drawContours( drawing, contours, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
  drawContours( drawing, hull, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
 }
 
 // Show in a window
 namedWindow( "Hull demo", CV_WINDOW_AUTOSIZE );
 imshow( "Hull demo", drawing );
 
 waitKey(0);
 return(0);
}

Just this part would be enough .

vector<vector<Point> >hull( contours.size() );
 for( int i = 0; i < contours.size(); i++ )
 {  convexHull( Mat(contours[i]), hull[i], false ); }
 
 // Draw contours + hull results
 RNG rng;
 Mat drawing = Mat::zeros( threshold_output.size(), CV_8UC3 );
 for( int i = 0; i< contours.size(); i++ )
 {
  Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );
  drawContours( drawing, contours, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
  drawContours( drawing, hull, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
 }

Originally Posted by KevinWorkman

I've moved this to the Other Programming Languages forum.

Generally, you don't translate a piece of code line-by-line. Instead, you translate the *intent* of the code as a whole. You ask yourself, "what does this piece of code do?" and then you ask yourself "now how would I do that in Java?"

So, what does this code do?

If I knew, I would have already written the Java code for that. specially I don't know about that vector part.

I have already converted the first few lines. Just having a hard time understanding and converting this particular area. I can edit it once it is converted as I am not familiar with C++