我有一个按钮，它获取用户选择的图像，然后在 imageView 中设置它（注意：它在视图中显示选定的图像，然后当用户单击按钮时，它在另一个图像视图中设置它）我这样做了在后台的相同活动中，它工作正常，在查看我的代码后，我不确定 NULL 会发生什么以及如何修复它。这是错误：
11-14 15:56:07.387: E/AndroidRuntime(25894): FATAL EXCEPTION: main
11-14 15:56:07.387: E/AndroidRuntime(25894): java.lang.NullPointerException
11-14 15:56:07.387: E/AndroidRuntime(25894): at com.example.awesomefilebuilderwidget.Personalize.scaleDownBitmapForIcon(Personalize.java:127)
11-14 15:56:07.387: E/AndroidRuntime(25894): at com.example.awesomefilebuilderwidget.Personalize.setIconImageInWidget(Personalize.java:98)
11-14 15:56:07.387: E/AndroidRuntime(25894): at com.example.awesomefilebuilderwidget.Personalize.onClick(Personalize.java:87)
11-14 15:56:07.387: E/AndroidRuntime(25894): at android.view.View.performClick(View.java:2532)
11-14 15:56:07.387: E/AndroidRuntime(25894): at android.view.View$PerformClick.run(View.java:9308)
11-14 15:56:07.387: E/AndroidRuntime(25894): at android.os.Handler.handleCallback(Handler.java:587)
11-14 15:56:07.387: E/AndroidRuntime(25894): at android.os.Handler.dispatchMessage(Handler.java:92)
11-14 15:56:07.387: E/AndroidRuntime(25894): at android.os.Looper.loop(Looper.java:150)
11-14 15:56:07.387: E/AndroidRuntime(25894): at android.app.ActivityThread.main(ActivityThread.java:4333)
11-14 15:56:07.387: E/AndroidRuntime(25894): at java.lang.reflect.Method.invokeNative(Native Method)
11-14 15:56:07.387: E/AndroidRuntime(25894): at java.lang.reflect.Method.invoke(Method.java:507)
11-14 15:56:07.387: E/AndroidRuntime(25894): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-14 15:56:07.387: E/AndroidRuntime(25894): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-14 15:56:07.387: E/AndroidRuntime(25894): at dalvik.system.NativeStart.main(Native Method)
这是我的 Personalize.java：
public class Personalize extends Activity implements View.OnClickListener
{
Button button;
ImageView image;
ImageView image2;
Button btnChangeImage;
Button btnChangeImageForIcon;
Button btnSetBackground;
private static final int SELECT_PICTURE = 1;
private static final int SELECT_PICTURE_2 = 2;
private String selectedImagePath;
Bitmap background;
Bitmap b2;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.personalize);
Log.d("Personalize", "OnCreate called");
image = (ImageView) findViewById(R.id.imageView1);
image2 = (ImageView) findViewById(R.id.imageView2Icon);
Button btnChangeImage = (Button) findViewById(R.id.btnChangeImage);
btnChangeImage.setOnClickListener(this);
Button btnChangeImageForIcon = (Button) findViewById(R.id.btnChangeImageForIcon);
btnChangeImageForIcon.setOnClickListener(this);
Button btnSetBackground = (Button) findViewById(R.id.btnSetBackground);
btnSetBackground.setOnClickListener(this);
Button btnLinkToFeedback = (Button) findViewById(R.id.btnLinkToFeedback);
Button btnSetIcon = (Button) findViewById(R.id.btnSetIcon);
btnSetIcon.setOnClickListener(this);
// Link to Feedback Screen
btnLinkToFeedback.setOnClickListener(new View.OnClickListener() {
public void onClick(View view)
{
Intent i = new Intent(getApplicationContext(), Feedback.class);
startActivity(i);
Log.d("Personalize", "LinkToFeedBack called");
finish();
}
});
}
@Override
public void onClick(View v)
{
switch (v.getId()) {
case R.id.btnChangeImage:
launchImageChooser();
break;
case R.id.btnChangeImageForIcon:
launchImageChooser2();
break;
case R.id.btnSetBackground:
setBackgroundImageInDragAndDrop();
break;
case R.id.btnSetIcon:
setIconImageInWidget();
break;
}
}
private void setIconImageInWidget()
{
// TODO Auto-generated method stub
Log.d("Personalize", "setIconImageInWidget() called");
Intent i = getIntent();
// Convert bitmap to byte array to send back to activity
// See: http://stackoverflow.com/questions/11010386/send-bitmap-using-intent-android
scaleDownBitmapForIcon(b2, 500, this.getBaseContext());
Log.d("Personalize", "Scale Bitmap Chosen For Icon");
ByteArrayOutputStream stream = new ByteArrayOutputStream();
b2.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
i.putExtra("myIconBitmap", byteArray);
setResult(RESULT_OK, i);
finish();
}
public static Bitmap scaleDownBitmap(Bitmap background, int newHeight, Context c)
{
final float densityMultiplier = c.getResources().getDisplayMetrics().density;
int h = (int) (500 * densityMultiplier);
int w = (int) (h * background.getWidth() / ((double) background.getHeight()));
background = Bitmap.createScaledBitmap(background, w, h, true);
// TO SOLVE LOOK AT HERE:http://stackoverflow.com/questions/15517176/passing-bitmap-to-
// other-activity-getting-message-on-logcat-failed-binder-transac
return background;
}
public static Bitmap scaleDownBitmapForIcon(Bitmap b2, int newHeight, Context c)
{
final float densityMultiplier = c.getResources().getDisplayMetrics().density;
int h = (int) (500 * densityMultiplier);
int w = (int) (h * b2.getWidth() / ((double) b2.getHeight()));
b2 = Bitmap.createScaledBitmap(b2, w, h, true);
// TO SOLVE LOOK AT
// HERE:http://stackoverflow.com/questions/15517176/passing-bitmap-to-other-activity-getting-message-on-logcat-failed-binder-transac
return b2;
}
private void setBackgroundImageInDragAndDrop()
{
Log.d("Personalize", "setBackgroundImageInDragAndDrop() called");
Intent i = getIntent();
// Convert bitmap to byte array to send back to activity
// See: http://stackoverflow.com/questions/11010386/send-bitmap-using-intent-android
scaleDownBitmap(background, 500, this.getBaseContext());
Log.d("Personalize", "Scale Bitmap Chosen");
ByteArrayOutputStream stream = new ByteArrayOutputStream();
background.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
i.putExtra("myBackgroundBitmap", byteArray);
setResult(RESULT_OK, i);
finish();
}
private void launchImageChooser()
{
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
startActivityForResult(intent, SELECT_PICTURE);
Log.d("Personalize", "launchImageChooser called");
}
private void launchImageChooser2()
{
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
startActivityForResult(intent, SELECT_PICTURE_2);
Log.d("Personalize", "launchImageChooser2 called");
}
public String getPath(Uri uri)
{
String[] projection = { MediaStore.Images.Media.DATA };
Cursor cursor = getContentResolver().query(uri, projection, null, null, null);
int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
String imagePath = cursor.getString(column_index);
if (cursor != null) {
cursor.close();
}
return imagePath;
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data)
{
if (resultCode == RESULT_OK) {
if (requestCode == SELECT_PICTURE) {
Uri selectedImageUri = data.getData();
selectedImagePath = getPath(selectedImageUri);
background = getAndDecodeImage(selectedImagePath);
if (background != null) {
image.setImageBitmap(background);
}
} else if (requestCode == SELECT_PICTURE_2) {
Uri selectedImageUri = data.getData();
selectedImagePath = getPath(selectedImageUri);
Bitmap b2 = getAndDecodeImage(selectedImagePath);
if (b2 != null) {
image2.setImageBitmap(b2);
}
}
}
}
private Bitmap getAndDecodeImage(String selectedImagePath)
{
try {
Log.d("Personalize", "selectedImagePath: " + selectedImagePath);
FileInputStream fileis = new FileInputStream(selectedImagePath);
BufferedInputStream bufferedstream = new BufferedInputStream(fileis);
byte[] bMapArray = new byte[bufferedstream.available()];
bufferedstream.read(bMapArray);
Bitmap bMap = BitmapFactory.decodeByteArray(bMapArray, 0, bMapArray.length);
if (fileis != null) {
fileis.close();
}
if (bufferedstream != null) {
bufferedstream.close();
}
return bMap;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
public boolean saveImageToInternalStorage(Bitmap image)
{
try {
FileOutputStream fos = this.openFileOutput("desiredFilename.png", Context.MODE_PRIVATE);
image.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.close();
return true;
} catch (Exception e) {
return false;
}
}
}
谢谢！
新的 NPE：
11-14 16:47:54.498: E/AndroidRuntime(27568): FATAL EXCEPTION: main
11-14 16:47:54.498: E/AndroidRuntime(27568): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=10, result=-1, data=Intent { cmp=com.example.awesomefilebuilderwidget/.Personalize (has extras) }} to activity {com.example.awesomefilebuilderwidget/com.example.awesomefilebuilderwidget.Drag_and_Drop_App}: java.lang.NullPointerException
11-14 16:47:54.498: E/AndroidRuntime(27568): at android.app.ActivityThread.deliverResults(ActivityThread.java:2974)
11-14 16:47:54.498: E/AndroidRuntime(27568): at android.app.ActivityThread.handleSendResult(ActivityThread.java:3026)
11-14 16:47:54.498: E/AndroidRuntime(27568): at android.app.ActivityThread.access$2000(ActivityThread.java:135)
11-14 16:47:54.498: E/AndroidRuntime(27568): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1071)
11-14 16:47:54.498: E/AndroidRuntime(27568): at android.os.Handler.dispatchMessage(Handler.java:99)
11-14 16:47:54.498: E/AndroidRuntime(27568): at android.os.Looper.loop(Looper.java:150)
11-14 16:47:54.498: E/AndroidRuntime(27568): at android.app.ActivityThread.main(ActivityThread.java:4333)
11-14 16:47:54.498: E/AndroidRuntime(27568): at java.lang.reflect.Method.invokeNative(Native Method)
11-14 16:47:54.498: E/AndroidRuntime(27568): at java.lang.reflect.Method.invoke(Method.java:507)
11-14 16:47:54.498: E/AndroidRuntime(27568): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-14 16:47:54.498: E/AndroidRuntime(27568): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-14 16:47:54.498: E/AndroidRuntime(27568): at dalvik.system.NativeStart.main(Native Method)
11-14 16:47:54.498: E/AndroidRuntime(27568): Caused by: java.lang.NullPointerException
11-14 16:47:54.498: E/AndroidRuntime(27568): at com.example.awesomefilebuilderwidget.Drag_and_Drop_App.onActivityResult(Drag_and_Drop_App.java:180)
11-14 16:47:54.498: E/AndroidRuntime(27568): at android.app.Activity.dispatchActivityResult(Activity.java:4053)
11-14 16:47:54.498: E/AndroidRuntime(27568): at android.app.ActivityThread.deliverResults(ActivityThread.java:2970)
11-14 16:47:54.498: E/AndroidRuntime(27568): ... 11 more
onActivityResult（如错误所述）：
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
Log.i("Drag_and_Drop_App", "requestCode: " + requestCode + ", resultCode: " + resultCode);
if(requestCode == SET_BACKGROUND && resultCode == RESULT_OK){
byte[] byteArray = data.getByteArrayExtra("myBackgroundBitmap");
Bitmap myBackground = BitmapFactory.decodeByteArray(byteArray, 0, byteArray.length);
setBackgroundImage(myBackground);
}
else if(requestCode == SET_ICON && resultCode == RESULT_OK){
byte[] byteArray = data.getByteArrayExtra("myIconBitmap");
Bitmap myIcon = BitmapFactory.decodeByteArray(byteArray, 0, byteArray.length);
setBackgroundImageForIcon(myIcon);
}
}