I am new to java and I could use some help. In the following program, when I rotate the screen the ListView disappears. When I click back, then pull the app back up both of my TextViews and my ListView are cleared. I read up on this some and from what I gather it's because the activity basically restarts upon these actions. I looked for a good way to save the information in these cases, but nothing I tried is working. Any help would be greatly appreciated. If my code is a mess, I apologize, like I said I'm a beginner. I tried to use the onSavedInstanceState() method, but I can't get it to work. I realize it's probably some stupid mistake that I am making, but I have been at it for hours and I can't figure out what I'm doing wrong. Thanks in advance.
package dev.rogueinteractive.barcodescannershoppingcartii;
import android.app.Activity;
import android.os.StrictMode;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import com.google.zxing.integration.android.IntentIntegrator;
import com.google.zxing.integration.android.IntentResult;
import android.content.Intent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity implements OnClickListener {
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
savedInstanceState.putStringArrayList("myKey", (ArrayList<String>) productReport);
}
private static final String USER_AGENT = "Mozilla/5.0";
private static String GET_URL ;
private ArrayAdapter<String> listAdapter ;
List<String> productReport = new ArrayList<String>();
public void sendGET() throws IOException {
URL obj = new URL(GET_URL);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
con.setRequestMethod("GET");
con.setRequestProperty("User-Agent", USER_AGENT);
int responseCode = con.getResponseCode();
System.out.println("GET Response Code :: " + responseCode);
if (responseCode == HttpURLConnection.HTTP_OK) { // success
BufferedReader in = new BufferedReader(new InputStreamReader(
con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
// print result
fullResponse = response.toString();
String[]responseArray = fullResponse.split("\"");
String price = new String(responseArray[30]);
price = new StringBuffer(price).insert(1, " ").toString();
price = new StringBuffer(price).insert(2, "$").toString();
responseArray[30] = price;
List<String> modifiedArray = new ArrayList<String>();
modifiedArray.add(responseArray[27]);
modifiedArray.add("\n");
modifiedArray.add("\n");
modifiedArray.add(responseArray[28]);
modifiedArray.add(responseArray[29]);
modifiedArray.add(responseArray[30]);
modifiedResponse = modifiedArray.toString();
modifiedResponse= modifiedResponse.replaceAll(",", "");
modifiedResponse = modifiedResponse.replaceAll("[\\[\\]]", "");
productReport.add(modifiedResponse);
} else {
responseTXT.setText("GET request not worked");
}
}
public String modifiedResponse;
public String fullResponse;
public String scanContent;
private Button scanBtn;
private TextView formatTxt, contentTxt, responseTXT;
public ListView mainListView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState != null) {
List<String> productReport = savedInstanceState.getStringArrayList("myKey");
if (productReport != null) {
listAdapter = new ArrayAdapter<String>(this, R.layout.simplerow, productReport);
}
}
setContentView(R.layout.activity_main);
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
mainListView = (ListView) findViewById( R.id.mainListView );
scanBtn = (Button) findViewById(R.id.scan_button);
formatTxt = (TextView) findViewById(R.id.scan_format);
contentTxt = (TextView) findViewById(R.id.scan_content);
responseTXT = (TextView) findViewById(R.id.response);
scanBtn.setOnClickListener(this);
}
public void onClick(View v) {
if (v.getId() == R.id.scan_button) {
IntentIntegrator scanIntegrator = new IntentIntegrator(this);
scanIntegrator.initiateScan();
}
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent intent) {
IntentResult scanningResult = IntentIntegrator.parseActivityResult(requestCode, resultCode, intent);
if (scanningResult.getFormatName() != null) {
this.scanContent = scanningResult.getContents();
String scanFormat = scanningResult.getFormatName();
formatTxt.setText("FORMAT: " + scanFormat);
contentTxt.setText("CONTENT: " + scanContent);
GET_URL="http://api.walmartlabs.com/v1/search?query="+scanContent+"&format=json&apiKey=5sk5b7u25b4qawku5zsm289z";
try {
sendGET();
} catch (IOException e) {
e.printStackTrace();
}
listAdapter = new ArrayAdapter<String>(this, R.layout.simplerow, productReport);
mainListView.setAdapter( listAdapter );
} else if (scanningResult==null){
Toast toast = Toast.makeText(getApplicationContext(),
"No scan data received!", Toast.LENGTH_SHORT);
toast.show();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Main Activity
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<Button android:id="@+id/scan_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:text="@string/scan" />
<TextView
android:id="@+id/scan_format"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textIsSelectable="true"
android:layout_centerHorizontal="true"
android:layout_below="@id/scan_button" />
<TextView
android:id="@+id/scan_content"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textIsSelectable="true"
android:layout_centerHorizontal="true"
android:layout_below="@id/scan_format" />
<ListView android:id="@+id/mainListView"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:layout_below="@id/scan_content"/>
<TextView
android:id="@+id/response"
android:maxLines = "10000"
android:scrollbars = "vertical"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textIsSelectable="true"
android:layout_centerHorizontal="true"
android:layout_below="@id/scan_content" />
</RelativeLayout>
Row Layout
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/rowTextView"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:textSize="16sp" >
</TextView>
