This is a task from lab classes at my university. Problem statement was to showcase following features:
- Multiple activities in app.
- Passing data from one activity to another.
- Changing behavior of back button in one of activities.
- Getting picture from camera and displaying it in app.
- Binding callback action in XML file instead of Java code.
It's based heavily on examples, but I wonder if I can get any general advice about code quality.
Whole project on GitHub: https://github.com/rogalski/tmlab2
And Java and layout code:
MyActivity.java:
package lab.tm.rogalski.lab2;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class MyActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setListeners();
}
@Override
public void onResume() {
EditText editText = (EditText) findViewById(R.id.TextToSend);
editText.setText("");
super.onResume();
}
private void setListeners() {
Button sendButton = (Button) findViewById(R.id.SendBtn);
sendButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
EditText editText = (EditText) findViewById(R.id.TextToSend);
String data = editText.getText().toString();
sendIntent(data);
}
});
}
private void sendIntent(String data) {
Intent intent = new Intent(this, SecondActivity.class);
intent.putExtra("data", data);
startActivity(intent);
}
}
SecondActivity.java
package lab.tm.rogalski.lab2;
import android.app.Activity;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class SecondActivity extends Activity {
static final int REQUEST_TAKE_PHOTO = 1;
String mCurrentPhotoPath;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second);
retrieveIntentData();
}
private void retrieveIntentData() {
Intent intent = getIntent();
TextView target = (TextView) findViewById(R.id.TextDestination);
target.setText(intent.getStringExtra("data"));
}
private void showPicture() {
if (mCurrentPhotoPath == null)
return;
ImageView iv = (ImageView) findViewById(R.id.imageView);
iv.setImageBitmap(BitmapFactory.decodeFile(mCurrentPhotoPath));
}
@Override
public void onBackPressed() {
Toast.makeText(this, "Back button disabled. Use a button above.", Toast.LENGTH_SHORT).show();
// super.onBackPressed();
}
public void onBtnClick(View v) {
Intent intent = new Intent(this, MyActivity.class);
startActivity(intent);
}
public void onTakePhotoBtnClick(View v) {
dispatchTakePictureIntent();
}
private void dispatchTakePictureIntent() {
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) == null) {
Toast.makeText(this, "Camera not detected.", Toast.LENGTH_SHORT).show();
}
File photoFile = null;
try {
photoFile = createImageFile();
} catch (IOException ex) {
Log.d("TAG", Log.getStackTraceString(ex));
Toast.makeText(this, "Failed to create image file.", Toast.LENGTH_SHORT).show();
}
if (photoFile != null) {
takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photoFile));
startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
}
}
private File createImageFile() throws IOException {
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
String imageFileName = "JPEG_" + timeStamp + "_";
File storageDir = getApplicationContext().getExternalFilesDir(Environment.DIRECTORY_PICTURES);
if (isExternalStorageWritable() && !storageDir.isDirectory()) {
storageDir.mkdirs();
}
File image = File.createTempFile(imageFileName, ".jpg", storageDir);
mCurrentPhotoPath = image.getAbsolutePath();
return image;
}
public boolean isExternalStorageWritable() {
String state = Environment.getExternalStorageState();
return Environment.MEDIA_MOUNTED.equals(state);
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
showPicture();
}
}
main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/TextToSend" android:layout_gravity="center_horizontal"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send to another activity"
android:id="@+id/SendBtn" android:layout_gravity="center_horizontal"/>
</LinearLayout>
second.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:id="@+id/TextDestination" android:layout_gravity="center_horizontal"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Go Back To Main Activity"
android:id="@+id/GoBackBtn" android:layout_gravity="center_horizontal" android:onClick="onBtnClick"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Take Picture"
android:id="@+id/button" android:layout_gravity="center_horizontal" android:onClick="onTakePhotoBtnClick"/>
<ImageView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/imageView" android:layout_gravity="center_horizontal"/>
</LinearLayout>
