Activity Lifecycle if button Home pressed Android example
If on Android emulator home button pressed.
Diagram of Activity lifecycle if button HOME pressed
// button home presssed
19:37:06.727: INFO/ActivityManager(60): Starting:
Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME]
flg=0x10200000 cmp=com.android.launcher/com.android.launcher2.Launcher } from pid 60
19:37:06.807: INFO/onSaveInstanceState(339): onSaveInstanceState()
19:37:06.848: INFO/onPause(339): onPause()
19:37:07.968: INFO/onStop(339): onStop()
Diagram of Activity lifecycle if button HOME pressed

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String[] sAr = new String[] {"one","two","three"};
List<String> wordList = Arrays.asList(sAr);
Collections.shuffle( wordList);
String[]myShuffledArray = wordList.toArray(new String[wordList.size()]);
public static Bitmap createBitmap (int[] colors, int offset, int stride, int width, int height, Bitmap.Config config)
public void drawBitmap (Bitmap bitmap, float left, float top, Paint paint)
public void drawBitmap (Bitmap bitmap, float left, float top, Paint paint)
// //www.apache.org/licenses/LICENSE-2.0
public class MainActivity extends Activity {
private static final int WIDTH = 50;
private static final int HEIGHT = 50;
private static final int STRIDE = 64; // must be >= WIDTH
private static int[] createColors() {
int[] colors = new int[STRIDE * HEIGHT];
for (int y = 0; y < HEIGHT; y++) {
for (int x = 0; x < WIDTH; x++) {
int r = x * 255 / (WIDTH - 1);
int g = y * 255 / (HEIGHT - 1);
int b = 255 - Math.min(r, g);
int a = Math.max(r, g);
colors[y * STRIDE + x] = (a << 24) | (r << 16) | (g << 8) | b;
}
}
return colors;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
private static class SampleView extends View {
// CONSTRUCTOR
public SampleView(Context context) {
super(context);
setFocusable(true);
}
@Override
protected void onDraw(Canvas canvas) {
Paint paint = new Paint();
canvas.drawColor(Color.GREEN);
int[] mColors = createColors();
int[] colors = mColors;
Bitmap bitmap = Bitmap.createBitmap(colors, 0, STRIDE, WIDTH, HEIGHT,
Bitmap.Config.RGB_565);
canvas.drawBitmap(bitmap, 50,20, paint);
}
}
}
Copy file to another
Copy and compress file
File path = Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES);
File file = new File(path, "MyPicture.jpg");
// the Pictures directory exists?
path.mkdirs();
InputStream is = getResources().openRawResource(R.drawable.flower_blue);
OutputStream os = new FileOutputStream(file);
byte[] data = new byte[is.available()];
is.read(data);
os.write(data);
is.close();
os.close();
Copy and compress file
Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),
R.drawable.flower_blue);
try {
FileOutputStream out = new FileOutputStream("new_bitmap.jpg");
bitmapOrg.compress(Bitmap.CompressFormat.JPEG, 90, out);
} catch (Exception e) {
e.printStackTrace();
Log.e("saveBitmap", e.getMessage());
}
Log.e println needs a message error.
E/AndroidRuntime(330): FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{b.paint/b.paint.MainActivity}: java.lang.NullPointerException: println needs a message
Try this code:
E/AndroidRuntime(330): FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{b.paint/b.paint.MainActivity}: java.lang.NullPointerException: println needs a message
Try this code:
// Error
String s = null;
Log.e("bla", s); // !!! error Log.e println needs a message error.
// OK
String s = null;
Log.e("bla", s+""); // OK
public class ApokusActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
private static class SampleView extends View {
// CONSTRUCTOR
public SampleView(Context context) {
super(context);
setFocusable(true);
}
@Override
protected void onDraw(Canvas canvas) {
Paint paint = new Paint();
canvas.drawColor(Color.YELLOW);
paint.setFilterBitmap(true);
Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),R.drawable.flower_blue);
int targetWidth = bitmapOrg.getWidth() * 2;
int targetHeight = bitmapOrg.getHeight() * 2;
Bitmap bmp = Bitmap.createBitmap(targetWidth, targetHeight,Bitmap.Config.ARGB_8888);
RectF rectf = new RectF(0, 0, targetWidth, targetHeight);
Canvas c = new Canvas(bmp);
Path path = new Path();
path.addRect(rectf, Path.Direction.CW);
c.clipPath(path);
c.drawBitmap( bitmapOrg, new Rect(0, 0, bitmapOrg.getWidth(), bitmapOrg.getHeight()),
new Rect(0, 0, targetWidth, targetHeight), paint);
Matrix matrix = new Matrix();
matrix.postScale(1f, 1f);
Bitmap resizedBitmap = Bitmap.createBitmap(bmp, 0, 0, targetWidth, targetHeight, matrix, true);
int h = bitmapOrg.getHeight();
canvas.drawBitmap(bitmapOrg, 10,10, paint);
canvas.drawBitmap(resizedBitmap, 10,10 + h + 10, paint);
}
}
}

Editace: 2011-10-08 19:56:29
Počet článků v kategorii: 396
Url:activity-lifecycle-if-button-home-pressed-android-example