Develop Reference

Android Studio Java display text file contents in new lines

Im creating a weight tracking app where the user inputs their weight clicks a save button and then the weight is saved. There is also a load button that loads all the previous inputs. The problem I'am having is that once load is clicked it does load up the weights on the screen but it does it all in one line other than a separate line for each.
I have checked the text file and all the weights are stored in a line each so there's no problem in the function that stores the inputs.
Here is the code for the `weight tracker
package com.example.workouttracker;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
public class WeightTracking extends AppCompatActivity {
private static final String FILE_NAME = "WeightTracking.txt";
EditText mEditText;
EditText mEditText2;
private Button button_back_home;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_weight_tracking);
mEditText = findViewById(R.id.weight);
mEditText2 = findViewById(R.id.weight2);
button_back_home=(Button) findViewById(R.id.button_back_home);
button_back_home.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
homePage();
}
private void homePage(){
startActivity(new Intent(getApplicationContext(),MainActivity.class).setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP));
}
});
}
public void save(View v) {
String text = mEditText.getText().toString();
FileOutputStream fos = null;
try {
fos = openFileOutput(FILE_NAME, MODE_APPEND);
fos.write((text + "kg's\n").getBytes());
mEditText.getText().clear();
Toast.makeText(this, "Saved to " + getFilesDir() + "/" + FILE_NAME,
Toast.LENGTH_LONG).show();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (fos != null) {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public void load(View v) {
FileInputStream fis = null;
try {
fis = openFileInput(FILE_NAME);
InputStreamReader isr = new InputStreamReader(fis);
BufferedReader br = new BufferedReader(isr);
StringBuilder sb = new StringBuilder();
String text;
while ((text = br.readLine()) != null) {
sb.append(text);
sb.append('\n');
}
mEditText2.setText(sb.toString());
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (fis != null) {
try {
fis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
Someone know's how to get it to load each weight line by line?
Thanks
`

can you please check your xml file, if you have added property android:inputType="textMultiLine" on the edittext

Try changing your code like this:
String sb = "";
String text;
while ((text = br.readLine()) != null) {
sb = sb + text + "\n";
}

Why does my android shareIntent not work?

I have a soundboard app and am trying to enable the user to share the sounds from my res/raw folder. My code seems to properly create a folder and copy the resource into it. However, when trying to share, I always get an error from the external app. (e.g. gmail says: "Cannot attach file"). Can anyone please help?
The code:
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Environment;
import android.util.Log;
import android.widget.Toast;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
public class Pls {
public void sendAudio(Activity activity){
try {
String mediaPath = copyFiletoExternalStorage(R.raw.audio_file, "audiofile.mp3",activity);
Intent shareMedia = new Intent(Intent.ACTION_SEND);
shareMedia.setType("audio/*");
shareMedia.putExtra(Intent.EXTRA_STREAM, Uri.parse(mediaPath));
activity.startActivity(Intent.createChooser(shareMedia, "Select app"));
} catch (Exception e) {
Toast.makeText(activity.getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
}
}
private String copyFiletoExternalStorage(int resourceId, String resourceName,Activity activity){
String pathSDCard = Environment.getExternalStorageDirectory() + "/Android/data/" + resourceName;
try{
InputStream in = activity.getResources().openRawResource(resourceId);
FileOutputStream out = null;
out = new FileOutputStream(pathSDCard);
byte[] buff = new byte[1024];
int read = 0;
try {
while ((read = in.read(buff)) > 0) {
out.write(buff, 0, read);
}
} finally {
in.close();
out.close();
}
} catch (IOException e) {
Log.i("err",e.toString());
}
return pathSDCard;
}
}

The getAssets() method in the Android library does not work

As a newbie to Android programming, I have attached four files to the assets folder of my library.
You can see the attached image.
I want to access these files through the Android library using the below code (if I don't use this code in Android library, it runs without an error when I use it in MainActivity).
public void copy_weights() {
try {
AssetManager assetFiles = getAssets();
String[] files = assetFiles.list("");
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (NullPointerException e) {
e.printStackTrace(); //catch the error in this line
} catch (Exception e) {
e.printStackTrace();
}
}
but this code give me the error:
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.AssetManager android.Context.getAssets' on a null object refrence
I tried other methods like direct accessing via home:///android_asset/7.cfg but it can't access the files too.
EDIT 1
I call the copy_weights() in mainActivity like below
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
final new_class newClass=new new_class();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button button =(Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
TextView textView=(TextView) findViewById(R.id.textView);
newClass.copy_weights();
}
});
}
EDIT 2
new_class code
package com.example.mylittlelibrary;
import android.content.res.AssetManager;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.dnn.Net;
import org.opencv.imgcodecs.Imgcodecs;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.File;
public class new_class extends AppCompatActivity {
private boolean opencv_sucessfully_included;
private static int BUFFER_SIZE = 1024;
public new_class() { }
private static void copyAssetFiles(InputStream in, OutputStream out) {
try {
byte[] buffer = new byte[BUFFER_SIZE];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch (IOException e) {
e.printStackTrace();
} catch (NullPointerException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
public void copy_weights() {
try {
AssetManager assetFiles = getAssets();
// MyHtmlFiles is the name of folder from inside our assets folder
String[] files = assetFiles.list("");
// Initialize streams
InputStream in = null;
OutputStream out = null;
for (int i = 0; i < files.length; i++) {
File file = new File(Environment.getExternalStorageDirectory() + "/" + files[i]);
if (!file.exists()) {
in = assetFiles.open(files[i]);
out = new FileOutputStream(Environment.getExternalStorageDirectory() + "/" + files[i]);
copyAssetFiles(in, out);
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (NullPointerException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
}

You can't initialize an Activity like that. If you need a reference to a Context (such as with getAssets()) you should pass it to the class.
First, remove your AppCompatActivity extension:
public class new_class {
Then change your constructor and add a global variable:
private Context context;
public new_class(Context context) {
this.context = context;
}
You'll notice some of your methods are now in red and unresolved. Just add context. before them. For example
context.getAssets()
Make a new instance of that class by adding a this argument to it:
final new_class newClass = new new_class(this);
Also, you shouldn't put anything before super.onCreate() is called, so move that to go after it.

Reconnecting to Bluetooth in android / Reading after Reconnect

I have a program that establishes a Bluetooth connection, reads the InputStream to a textView, and can disconnect from the module. While I can successfully disconnect and reconnect to the module (HC-05) as many times as I please, I can't get an InputStream read anymore after I reconnect. I believe it is because I don't know how to reinitialize the thread I'm using to read the InputStream. I am very new to java and android programming, any help with this issue would be appreciated.This is my code:
The textView for the read display is called 'Status' and I am hoping to "reset" the thread upon the onclick connect().
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
public class MainActivity extends AppCompatActivity implements Runnable {
private BluetoothAdapter adapter;
private InputStream inputStream;
private OutputStream outputStream;
private Thread thread;
private TextView Status;
private TextView Connection;
private BluetoothSocket socket = null;
private boolean threadStatusInitial=true;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Status=(TextView) findViewById(R.id.StatusID);
Connection=(TextView) findViewById(R.id.ConnectionStatus);
adapter= BluetoothAdapter.getDefaultAdapter();
if(adapter==null){
Toast.makeText(this,"bluetooth is unavailable",Toast.LENGTH_SHORT).show();
finish();
return;
}
thread=new Thread(this);
}
public void connect(View view){
Set<BluetoothDevice> devices=adapter.getBondedDevices();
for(BluetoothDevice device:devices){
if(device.getName().startsWith("HC-05")){
try {
socket=device.createRfcommSocketToServiceRecord(device.getUuids()[0].getUuid());
socket.connect();
Connection.setText("Connected");
inputStream=socket.getInputStream();
outputStream=socket.getOutputStream();
if (threadStatusInitial){
thread.start();
threadStatusInitial=false; //this ensures that the thread.start() method will only be called during the first connection
}
} catch (IOException e) {
Toast.makeText(this,"Can't Connect",Toast.LENGTH_LONG).show();
e.printStackTrace();
}
break;
}
}
}
public void Disconnect(View view) throws InterruptedException {
if (inputStream != null) {
try {inputStream.close();} catch (Exception e) {}
inputStream = null;
}
if (outputStream != null) {
try {outputStream.close();} catch (Exception e) {}
outputStream = null;
}
if (socket != null) {
try {socket.close();} catch (Exception e) {Toast.makeText(this,"Can't Connect",Toast.LENGTH_LONG).show();}
socket = null;
}
Connection.setText("Disconnected");
}
#Override
public void run() {
String textInput = "hi";
byte[] writeBytes=textInput.getBytes();
if(outputStream!=null){
try {
outputStream.write(writeBytes);
} catch (IOException e) {
Toast.makeText(this,"Unable to Write to Bluetooth ",Toast.LENGTH_LONG).show();
e.printStackTrace();
}
}
while(inputStream!=null){
byte [] buffer=new byte[2048];
try {
int length=inputStream.read(buffer);
final String strReceived = new String(buffer, 0, length);
runOnUiThread(new Runnable(){
#Override
public void run() {
Status.setText(strReceived);
}});
} catch (IOException e) {
e.printStackTrace();
}
}
}
}

Saving string array list to internal file directory android

I'm currently developing an android application with makes some user data while running which is saved in two ArrayList. Once the application closes, I need to save the datas on to the internal memory but in my logcat I'm always getting the error IOException file not found.
I'm confused about why it always happen. The following is my code for my activity. Please help me!
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.text.Html;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.View;
import android.widget.Button;
public class MainActivity extends ActionBarActivity {
public static ArrayList<String> myArrayList=new ArrayList<String>();
public static ArrayList<String> myArrayListwr=new ArrayList<String>();
static int close=1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
close=1;
System.out.println("Oncreate called");
try{
final File dir = new File(getApplicationContext().getFilesDir() + "/file");
if(!(dir.exists()))
{
dir.mkdirs(); //create folders where write files
}
final File file = new File(dir+ "/lines.txt");
if(!(file.exists())) {
file.createNewFile();
}
BufferedReader br = new BufferedReader(new FileReader(file));
if (br.readLine() == null) {
close=0;
}
br.close();
}
catch (IOException exc) { exc.printStackTrace(); }
try {
if(myArrayList.size()==0 && close!=0)
{
System.out.println("retriving data from file lines");
FileInputStream input =openFileInput("lines.txt"); // Open input stream
DataInputStream din = new DataInputStream(input);
int sz = din.readInt(); // Read line count
for (int i=0;i<sz;i++) { // Read lines
String line = din.readUTF();
myArrayList.add(line);
}
din.close();
}
}
catch (IOException exc) { exc.printStackTrace(); }
try {
if(myArrayListwr.size()==0 && close!=0)
{
System.out.println("retriving data from file lineswr");
final File dirwr = new File(getApplicationContext().getFilesDir() + "/file");
if(!dirwr.exists())
dirwr.mkdirs(); //create folders where write files
final File filewr = new File(dirwr+ "/lineswr.txt");
if(!filewr.exists()) {
filewr.createNewFile();
}
FileInputStream inputwr = openFileInput("lineswr.txt"); // Open input stream
DataInputStream dinwr = new DataInputStream(inputwr);
int szwr = dinwr.readInt(); // Read line count
for (int iwr=0;iwr<szwr;iwr++) { // Read lines
String linewr = dinwr.readUTF();
myArrayListwr.add(linewr);
}
dinwr.close();
}
}
catch (IOException exc) { exc.printStackTrace(); }
Button phy = (Button) findViewById(R.id.button3);
Button mat = (Button) findViewById(R.id.button1);
Button bio = (Button) findViewById(R.id.button2);
Button chem = (Button) findViewById(R.id.button4);
}
#Override
public void onBackPressed() {
super.onBackPressed();
try {
if(myArrayList.size()!=0)
{
System.out.println("inside on back pressed saving data to lines");
//Modes: MODE_PRIVATE, MODE_WORLD_READABLE, MODE_WORLD_WRITABLE
String fileName = getApplicationContext().getFilesDir()+"/file/"+ "lines.txt";
FileOutputStream output = openFileOutput("lines.txt",MODE_PRIVATE);
DataOutputStream dout = new DataOutputStream(output);
dout.writeInt(myArrayList.size()); // Save line count
for(String line : myArrayList) // Save lines
dout.writeUTF(line);
dout.flush(); // Flush stream ...
dout.close(); // ... and close.
}
}
catch (IOException exc) { exc.printStackTrace(); }
try {
if(myArrayListwr.size()!=0)
{
System.out.println("inside on back pressed saving data to lineswr");
//Modes: MODE_PRIVATE, MODE_WORLD_READABLE, MODE_WORLD_WRITABLE
String fileNamewr = getApplicationContext().getFilesDir()+"/file/"+ "lineswr.txt";
FileOutputStream outputwr = openFileOutput("lineswr.txt",MODE_PRIVATE);
DataOutputStream doutwr = new DataOutputStream(outputwr);
doutwr.writeInt(myArrayListwr.size()); // Save line count
for(String linewr : myArrayListwr) // Save lines
doutwr.writeUTF(linewr);
doutwr.flush(); // Flush stream ...
doutwr.close(); // ... and close.
}
}
catch (IOException exc) { exc.printStackTrace(); }
Intent intent = new Intent(MainActivity.this, MainActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
intent.putExtra("EXIT", true);
startActivity(intent);
}
}