Customizing html string with your custom html tags in Android

HtmlCustomizer.java

package r.systems.demo1.utils;

import android.util.Log;

// jsoup library is required for this
// implementation 'org.jsoup:jsoup:1.11.3'
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

public class HtmlCustomizer {

    private String htmlBody;
    private static String TAG = "HtmlCustomizer";

    public HtmlCustomizer(String body){
        this.htmlBody = body;
    }

    public void setHtmlBody(String body){
        this.htmlBody = body;
    }

    public String getOriginalHtmlBody(){
        return this.htmlBody;
    }

    public String putTextAtParagraphLocation(int position, String htmlToAppend){
        String tempHtml = this.htmlBody;
        Document doc = Jsoup.parse(tempHtml);
        Elements newsHeadlines = doc.select("p");
        position--;
        if(newsHeadlines.size()>= position){
            int index = tempHtml.indexOf(newsHeadlines.get(position).toString());
            tempHtml = (new StringBuffer(tempHtml).insert(index+newsHeadlines.get(position).toString().length(), htmlToAppend)).toString();
        }
        return tempHtml;
    }


    public String putTextAtParagraphOccurance(int position, String htmlToAppend){
        String tempHtml = this.htmlBody;

        if(position <= 1){
            Log.e(TAG, "Position must be more than one");
            return tempHtml;
        }
        Document doc = Jsoup.parse(tempHtml);
        Elements newsHeadlines = doc.select("p");
        if(newsHeadlines.size()>= 0){
            int startIndex = 0;
            int newsIndex = 0;
            for (Element headline : newsHeadlines) {
                newsIndex++;
                if(newsIndex%position == 0) {
                    int index = tempHtml.indexOf(headline.toString(), startIndex);
                    if(index >= 0) {
                        tempHtml = (new StringBuffer(tempHtml).insert(index+headline.toString().length(), htmlToAppend)).toString();
                        startIndex = index+ headline.toString().length() + htmlToAppend.length();
                    }
                }
            }
        }
        return tempHtml;
    }
    
    
    public ArrayList<String> splitInTwo() {
        ArrayList<String> splittedHtml = new ArrayList<>();
        String fullHtml = Jsoup.clean(this.htmlBody, Whitelist.basic());
        Document doc = Jsoup.parse("<div>" + fullHtml + "</div>");
        Elements newsHeadlines = doc.select("div > *");
        if (newsHeadlines.size() > 0) {
            if (newsHeadlines.get(0).toString().startsWith("<p><img")) {
                newsHeadlines.remove(0);
            }
            int position = Math.round((float) newsHeadlines.size() / 2);
            String firstHtml = "", secondHtml = "";
            for (int i = 0; i < position; i++) {
                firstHtml = firstHtml + newsHeadlines.get(i).toString();
            }
            for (int i = position; i < newsHeadlines.size(); i++) {
                secondHtml = secondHtml + newsHeadlines.get(i).toString();
            }
            splittedHtml.add(firstHtml);
//                splittedHtml.add("<h1>HELLO BROTHER</h1>");   FOR TESTING PURPOSE
            splittedHtml.add(secondHtml);
            return splittedHtml;
        } else {
            return new ArrayList<>();
        }
    }
}

YourActivity.java

public class WebViewActivity extends AppCompatActivity {

    WebView wv_test;

    HtmlCustomizer htmlCustomizer;

    String html = <your html>;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_web_view);


        wv_test = (WebView) findViewById(R.id.wv_test);

        htmlCustomizer = new HtmlCustomizer(html);

      // TO SET THE HTML TAG AFTER A SPECIFIC <P> TAG LOCATION
//        wv_test.loadData(htmlCustomizer.putTextAtParagraphLocation(1, "<h1>THIS IS MY CUSTOM HTML</h1>"), "text/html", null);
      
      // TO REPEAT THE HTML TAG AFTER EVERY SPECIFIC <P> TAG LOCATIONS 
      // MUST BE MORE THAN 1
        wv_test.loadData(htmlCustomizer.putTextAtParagraphOccurance(2, "<h1>THIS IS MY CUSTOM HTML</h1>"), "text/html", null);
    }
}