My Open Twitter Search integrated also with Slack channel, posting as bot

PostSlack_BackGround.java

package org.new_year2018;

import android.os.AsyncTask;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;

import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;

public class PostSlack_BackGround extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... params) {

        HttpPost post = new HttpPost(params[0]);
        UrlEncodedFormEntity form;
        if (params.length == 5)
        {
            ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
            nameValuePairs.add(new BasicNameValuePair("token", params[1] ));
            nameValuePairs.add(new BasicNameValuePair("channel", params[2] ));
            nameValuePairs.add(new BasicNameValuePair("text", params[3] ));
            nameValuePairs.add(new BasicNameValuePair("blocks", params[4] ));
            try {
                form = new UrlEncodedFormEntity(nameValuePairs, HTTP.UTF_8);
                //form.setContentEncoding(HTTP.UTF_8);
                post.setEntity(form);
            } catch (UnsupportedEncodingException e) {
                // TODO Auto-generated catch block
                return "{\"error\":\""+e.getMessage()+"\"}";
            }
        }

        DefaultHttpClient client = new DefaultHttpClient();
        String response="";

        try {
            response = client.execute(post, new BasicResponseHandler());
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return "{\"error\":\""+e.getMessage()+"\"}";
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return "{\"error\":\""+e.getMessage()+"\"}";
        }
        return response;
    }
}

SlackActivity.java

showToast("Saving tweets to Slack .Net Programming!");
String slackTocken = getString(R.string.slackToken);
String slackPostMessage = "https://slack.com/api/chat.postMessage";
String slackChannel = "twitter2slack";
String slackTitle = textbox.getText().toString();
String slackBlocks = "[";
for(final Tweet item : TweetSearchActivity.mytweets ){
	boolean foundImage = false;
	String firstImage = "";
	slackBlocks += " { ";
	slackBlocks += "\"type\": \"section\",\n" +
			"        \"text\": {\n" +
			"            \"type\": \"mrkdwn\",\n" +
			"            \"text\": \"";
	slackBlocks += item.username+" @ "+ item.date.replace("+0000", "") + "\n";
	slackBlocks += item.message.replace("\"","'");
	for (int index =0; index < item.urls.size(); index++){
		String url = item.urls.get(index);
		if (url.startsWith("media_url")) {
			url = url.replace("media_url:", "");
			foundImage = true;
			firstImage = url;
		}
		slackBlocks  += "\n" + url.replace("\"","'");
	}
	slackBlocks += "\"\n" +
			"        }";
	if (foundImage) {
		slackBlocks += ",\n" +
				"        \"accessory\": {\n" +
				"            \"type\": \"image\",\n" +
				"            \"image_url\": \"";
		slackBlocks += firstImage;
		slackBlocks += "\",\n" +
				"            \"alt_text\": \"tweet image\"\n" +
				"        }";
	}
	slackBlocks += " } ,";
}
if (slackBlocks.endsWith(",")) {
	slackBlocks = slackBlocks.substring(0, slackBlocks.length() - 1);
}
slackBlocks += "]";
PostSlack_BackGround mySlackTask = new PostSlack_BackGround();
String[] params = new String[5];
params[0] = slackPostMessage;
params[1] = slackTocken;
params[2] = slackChannel;
params[3] = slackTitle;
params[4] = slackBlocks;
String response;
mySlackTask.execute(params);
try {
	response = mySlackTask.get();
	showToast(response);
} catch (InterruptedException e1) {
	// TODO Auto-generated catch block
	showToast(e1.getMessage());
	return ;
} catch (ExecutionException e1) {
	// TODO Auto-generated catch block
	showToast(e1.getMessage());
	return ;
}