Develop Reference

compiling cpp files on runtime Android Studio

I am making a compiling app with my custom made a language. This app will change the custom made language code automatically to a CPP code. So all I need to do is compile the CPP code on runtime.
I got stuck compiling a CPP file in my app.
I have already checked out using dexmaker and image-playground, but I had problems with the Gradle-build. They are somewhat old projects and I'm not really sure how to use it so I passed that one.
So I am trying to use the command line tool with the android studio. I have saved my CPP file and can use it I think. Below includes my file i/o code. This is my code.
Code:
public class Code_cpp extends AppCompatActivity {
private Context context;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.code_cpp);
TextView textView = (TextView) findViewById(R.id.view);
textView.setMovementMethod(new ScrollingMovementMethod());
context = this;
}
public void savebutton(View v) {
final EditText edit = (EditText) findViewById(R.id.edit_text);
TextView textView = (TextView) findViewById(R.id.view);
Log.v("EditText", edit.getText().toString());
String messageString = edit.getText().toString();
writeToFile(messageString,context);
Toast.makeText(getApplicationContext(), "saved", Toast.LENGTH_LONG).show();
}
private void writeToFile(String data,Context context) {
try {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(context.openFileOutput("config.cpp", Context.MODE_PRIVATE));
outputStreamWriter.write(data);
outputStreamWriter.close();
Log.e("Success", "File write Success ");
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
public void loadbutton(View v){
String msg = readFromFile(context);
TextView textView = (TextView) findViewById(R.id.view);
textView.setText(msg);
}
private String readFromFile(Context context) {
String ret = "";
try {
InputStream inputStream = context.openFileInput("config.cpp");
if ( inputStream != null ) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String receiveString = "";
StringBuilder stringBuilder = new StringBuilder();
while ( (receiveString = bufferedReader.readLine()) != null ) {
stringBuilder.append(receiveString).append("\n");
}
inputStream.close();
ret = stringBuilder.toString();
}
}
catch (FileNotFoundException e) {
Log.e("login activity", "File not found: " + e.toString());
} catch (IOException e) {
Log.e("login activity", "Can not read file: " + e.toString());
}
return ret;
}
public void run(View v){
try {
Process process = Runtime.getRuntime().exec("g++ config.cpp;./a.out");
BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
int read;
char[] buffer = new char[4096];
StringBuffer output = new StringBuffer();
while ((read = reader.read(buffer)) > 0) {
output.append(buffer, 0, read);
}
reader.close();
// Waits for the command to finish.
process.waitFor();
//return output.toString();
String result=output.toString();
TextView textView = (TextView) findViewById(R.id.view);
textView.setText(result);
} catch (IOException e) {
throw new RuntimeException(e);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
}
I get an error when I click the run button
Caused by: java.io.IOException: Cannot run program "g++": error=13, Permission denied
I don't want to root my phone because I don't want to use this app just on my phone but with other phones too when I download it. Do I have to try another way to compile this? Why do I get permission denied errors?

Retrieve the saved WiFi passwords from Android devices

I am developing an Android application in which I need to show the saved WiFi passwords in the mobile or tablet. Like for example, if my mobile is connected to any network that n/w password is saved in my mobile. I want to get it.

Unless you are rooted, I don't know of any way to do it. If you are rooted, or are willing to root your Galaxy for those nice guy points, you should be able to use a file manager (ASTRO, Root Browser, etc.) to find it.
Use the file manager to locate your data/misc/file folder, then look for wpa_supplicant.conf, or I assume it could be wep_supplicant.conf if his/her network is using WEP instead of WPA. Open the .conf file using a text editor (which is probably built into your file manager application, if not, add that to your shopping list). You should be able to read the password in plain text at that point.

Your Comments helped me to some extent to find out the solution to my question. Especially #Namik Kalavadia I am talking about you Thanks for that.
Finally here is the solution.
public class MainActivity extends Activity {
File file;
public StringBuffer ab;
public File savefile;
public InputStream in = null;
public String filename = "wpa_supplicant.conf";
public File ot_path;
Context context;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = getApplicationContext();
ot_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
Log.d("aaa", ""+ot_path.toString());
}
public void path(View v){
getPath();
}
private void getPath(){
file = Environment.getRootDirectory();
String ext = ".conf";
File list[] = file.listFiles();
ab = new StringBuffer();
if(list!=null){
fileNameSearch(list);
}
}
public void fileNameSearch(File list[]){
if(list!=null){
for(int f = 0;f<list.length;f++){
ab.append(list[f].getName()+"\n");
File fi = list[f];
String path = fi.getPath();
if(fi.isDirectory()){
fileNameSearch(fi.listFiles());
}
else if(path.endsWith(".conf")){
if(path.contains(filename)){
try{
File fileForParse = copyFile(path,ot_path);
in = new FileInputStream(fileForParse);
getStringFromInputStream(in);
Log.d("aaa", "conf I got it"+path);
}catch(Exception e){
e.printStackTrace();
}
}
}
}
}
else{
Log.d("aaa", "List is null in method");
}
}
private File copyFile(String inputPath, File outputPath) {
InputStream input = null;
OutputStream out = null;
try {
if (!outputPath.exists())
{
outputPath.mkdirs();
}
savefile = new File(outputPath,filename);
if (!savefile.exists()) {
savefile.createNewFile();
File f = new File(inputPath);
Log.d("aaa",""+f.length());
input = new FileInputStream(inputPath);
out = new FileOutputStream(savefile);
byte[] buffer = new byte[1024];
int read;
while ((read = input.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
Log.d("aaa",""+savefile.length());
input.close();
input = null;
out.flush();
out.close();
out = null;
}
} catch (FileNotFoundException fnfe1) {
Log.e("aaa", fnfe1.getMessage());
return null;
}
catch (Exception e) {
Log.e("aaa", e.getMessage());
return null;
}
return savefile;
}
#SuppressWarnings("deprecation")
private String getStringFromInputStream(InputStream is) {
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String line;
try {
br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
if(line.contains("ssid")||line.contains("psk")){
sb.append(line+"\n");
}
if(line.contains("}")){
sb.append("-----------------\n");
}
AlertDialog ad = new AlertDialog.Builder(MainActivity.this).create();
ad.setTitle("Lis of WiFi Passwords Saved in your Mobile");
ad.setMessage(sb);
ad.setButton("OK",new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
finish();
}
});
ad.show();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return sb.toString();
}
}

It is not possible as far as I know . It will be a security problem if sdk tools allows to do so .

Retrieving saved Wifi password programatically is not possible due to security issue.If you root your phone you may able to get it,but that too in an encrypted form.

how to create a gridview of images dynamically

i am working on an app in which i have to populate gridview of images dynamically. I am getting an array of image ids from server, i am decoding json array and getting the image ids. now i have stored all the images in my drawable folder, i want to show the images of the ids i am getting from the json, but i am stuck at this point i don't know how this. help
this is my main activity
public class MainActivity extends Activity {
GridView grid ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
grid = (GridView)findViewById(R.id.grid_view);
grid.setAdapter(new Adapter(this));
Button play = (Button)findViewById(R.id.play);
play.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
try {
playgame();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
protected void playgame() throws JSONException {
if(cardcount >=1 ){
BufferedReader reader=null;
data_to_send = "userId=" + userId ;
try
{
Log.e("inside try block", "get text");
// Defined URL where to send data
URL url = new URL("http://172.16.10.5/Ankur/andapp/request_Play.php");
// Send POST data request
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
wr.write(data_to_send);
wr.flush();
// Get the server response
reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
StringBuilder sb = new StringBuilder();
String line = null;
// Read Server Response
while((line = reader.readLine()) != null)
{
// Append server response in string
sb.append(line + "\n");
Log.e("inside", "while loop");
}
play_response = sb.toString();
}
catch(Exception ex)
{
}
finally
{
try
{
reader.close();
}
catch(Exception ex) {}
}
Log.e("play response from the server", ""+play_response);
}else
{
Toast.makeText(getApplicationContext(), "Sorry you don't have cards.buy a new card now", Toast.LENGTH_LONG).show();
}
JSONObject jo = new JSONObject(play_response);
pos1 = jo.getString("0");
pos2 = jo.getString("1");
pos3 = jo.getString("2");
pos4= jo.getString("3");
pos5 = jo.getString("4");
pos6= jo.getString("5");
pos7= jo.getString("6");
pos8= jo.getString("7");
pos9= jo.getString("8");
Log.e("value of 1st place of array", "array value "+pics[7]);
}

i recommend to use Loader. see this [documentation] (http://developer.android.com/guide/components/loaders.html)
thus you can transfer images loading in not ui thread in Loade

How to read next line from a text file

I want to read several lines from a text file. These line should be displayed one by one, when I click the next button. I am able to store the strings in a file and read the first line. But when I try to read the next line using the next button, it stops working. Can anybody tell me a solution for this. Thanks in advance.
I have defined the following,
BufferedReader buffreader;
String line;
String fav;
StringBuilder text;
InputStream instream;
String favQuote0;
This is in my oncreate method
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_save);
StringBuilder text = new StringBuilder();
try {
// open the file for reading
InputStream instream = openFileInput("myfilename.txt");
// if file the available for reading
if (instream != null) {
// prepare the file for reading
InputStreamReader inputreader = new InputStreamReader(instream);
BufferedReader buffreader = new BufferedReader(inputreader);
while (( line = buffreader.readLine()) != null) {
text.append(line);
text.append('\n');
fav = text.toString();
}
}
} catch (IOException e) {}
TextView tv1 = (TextView)findViewById(R.id.textView2);
tv1.setText(fav);
}
This is my next button
public void next (View view1) {
try {
// open the file for reading
InputStream instream = openFileInput("myfilename.txt");
// if file the available for reading
if (instream != null) {
while (( line = buffreader.readLine()) != null) {
text.append(line);
text.append('\n');
fav = text.toString();
}
}
} catch (IOException e) {}
TextView tv1 = (TextView)findViewById(R.id.textView2);
tv1.setText(fav);
}

Both answers do it the wrong way. I will post a description below my code. This is the proper way of doing it.
private int mCurrentLine;
private ArrayList<String> mLines;
private TextView mTextView;
private Button mButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_save);
mCurrentLine = -1;
mLines = new ArrayList<String>();
mTextView = (TextView) findViewById(R.id.text_view);
mButton = (Button) findViewById(R.id.button);
try {
readLinesAndSaveToArrayList();
}
catch (IOException e) {
e.printStackTrace();
}
setTextAndIncrement();
mButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
setTextAndIncrement();
}
});
}
private void readLinesAndSaveToArrayList() throws IOException {
File file = new File("myfilename.txt");
if (!file.exists()) {
throw new FileNotFoundException("myfilename.txt was unable to locate");
}
FileReader fileReader = new FileReader(file);
BufferedReader bufferedReader = new BufferedReader(fileReader);
String line;
while ((line = bufferedReader.readLine()) != null) {
mLines.add(line);
}
bufferedReader.close();
}
private void setTextAndIncrement() {
if (mCurrentLine == mLines.size() - 1) {
return;
}
mCurrentLine++;
mTextView.setText(mLines.get(mCurrentLine));
}
What I do is cache the file's contents in a scalable ArrayList. Each line will be assigned to an index in the array, eg. 0, 1, 2 and so on.
mCurrentLine takes care of positioning in the array. It starts at -1 because there is no current line. In the setTextAndIncrement() it will be set to 0, which in the array is the first index (the first line). The continuous calls will increment the position and take the next lines. If you come to the limit I have put in a check that looks if the mCurrentLine is equal to the max size of lines (mLines.size() - 1, a - 1 because arrays starts from 0 instead of 1).
Other than that I would advice you to use full length names on methods and variables; there is no need to keep them short, it will only make reading them harder. XML should also only contain low letters instead of camelCases.

Try this. This i working for me
BufferedReader reader = new BufferedReader(new InputStreamReader(instream));
StringBuffer bf = new StringBuffer();
String json = reader.readLine();
try {
do {
bf.append(json);
json = reader.readLine();
}while (json != null);
wt.flush();
wt.close();
Log.d("LOG", " read line output "+new String(bf)+" json "+json);
reader.close();
} catch (Exception e) {
e.printStackTrace(); }
wt is the bufferedwriter which i used to write line. I read from reader and write into file stored locally.

try {
// open the file for reading
InputStream instream = new FileInputStream("myfilename.txt");
// if file the available for reading
if (instream != null) {
// prepare the file for reading
InputStreamReader inputreader = new InputStreamReader(instream);
BufferedReader buffreader = new BufferedReader(inputreader);
String line;
// read every line of the file into the line-variable, on line at the time
while (buffreader.hasNext()) {
line = buffreader.readLine();
// do something with the line
}
}
} catch (Exception ex) {
// print stack trace.
} finally {
// close the file.
instream.close();
}

How to Get Specific Information From the Internet In Android App

im pretty new In Android App development, I need some help.
Im creating this simple dictionary application that prompts the user to enter a word and after a button press it will take that word to the internet, probably wikipedia.org and return that information to the User.
I used XML to develop the app textfield and button. And created a piece of text (ansa) which will be set to whatever the answer is using the OnClickListener,
I do not want to set up a webview
I just want the text to be set to the dictionary answer.
Here's what i have been able to do so far. There is this class to get data from google.
public class GetMethod {
public String getInternetData() throws Exception{
BufferedReader in = null;
String data = null;
try{
HttpClient client = new DefaultHttpClient();
URI website = new URI("http://www.google.com");
HttpGet request = new HttpGet();
request.setURI(website);
HttpResponse response = client.execute(request);
in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String l = "";
String nl = System.getProperty("line.separator");
while((l = in.readLine()) !=null){
sb.append(l + nl);
}
in.close();
data = sb.toString();
return data;
}finally{
if (in !=null){
try{
in.close();
return data;
}catch(Exception e){
e.printStackTrace();
}
}
}
}
And Another class where the XML is implemented
public class Dictionary extends Activity {
TextView ansa;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dictionary);
Button Search = (Button) findViewById(R.id.search);
ansa = (TextView) findViewById(R.id.ansa);
final GetMethod test = new GetMethod();
Search.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
String returned;
try {
returned = test.getInternetData();
ansa.setText(returned);
} catch (Exception e) {
ansa.setText("Failed");
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
}
When it executes I get the whole website's HTML
So I need help on how to take the user's word to the wiki website, and get only the text of the ansa, probably parse and store it to some string.
Thank You Alot.

You can use an API like Google Dictionary or dictionary.com.
But you will have to implement the HTTP client and parse the response. And then show the desired data .