我有一个照片编辑器安卓代码,我收到错误
'引起:java.lang.NullPointerException:尝试在com.example.photoeditor.HomeActivity.onActivityResult(HomeActivity。)的空对象引用上调用虚拟方法'void android.widget.ImageView.setImageURI(android.net.Uri)'。 Java的:169)”
代码如下:
package com.example.photoeditor;
import android.database.Cursor;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.provider.MediaStore.Images.Media;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v4.content.FileProvider;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Toast;
import android.widget.ImageView;
import android.graphics.BitmapFactory;
import android.graphics.Bitmap;
import java.io.File;
import java.io.IOException;
import java.text.DateFormat;
import java.util.Date;
import java.util.Objects;
import static android.Manifest.permission.CAMERA;
import static android.Manifest.permission.READ_EXTERNAL_STORAGE;
import static android.Manifest.permission.WRITE_EXTERNAL_STORAGE;
import static android.content.pm.PackageManager.PERMISSION_GRANTED;
public class HomeActivity extends AppCompatActivity {
private ImageView mImageView;
private static final String TAG = "HomeActivity";
private static final int GALLERY_RESULT = 1;
private static final int CAMERA_RESULT = 2;
private static final String FILE_PROVIDER_AUTHORITY = "com.example.photoeditor";
private static final int CAMERA_PERMISSION_REQ_CODE = 1001;
private static final int STORAGE_PERMISSION_REQ_CODE = 1002;
private String mCapturedImagePath;
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
}
public void openCamera(View view) {
// check for camera permission if not granted before
if (ContextCompat.checkSelfPermission(this, CAMERA) != PERMISSION_GRANTED) {
String[] cameraPermission = { CAMERA };
ActivityCompat.requestPermissions(this, cameraPermission, CAMERA_PERMISSION_REQ_CODE);
} else {
dispatchImageCaptureIntent();
}
}
public void openGallery(View view) {
// check for storage permission if not granted before
if (ContextCompat.checkSelfPermission(this, READ_EXTERNAL_STORAGE) != PERMISSION_GRANTED ||
ContextCompat.checkSelfPermission(this, WRITE_EXTERNAL_STORAGE) != PERMISSION_GRANTED) {
String[] storagePermissions = { READ_EXTERNAL_STORAGE, WRITE_EXTERNAL_STORAGE };
ActivityCompat.requestPermissions(this, storagePermissions, STORAGE_PERMISSION_REQ_CODE);
} else {
dispatchGalleryIntent();
}
}
private void dispatchGalleryIntent() {
Intent galleryIntent = new Intent(Intent.ACTION_PICK, Media.EXTERNAL_CONTENT_URI);
startActivityForResult(galleryIntent, GALLERY_RESULT);
}
private void dispatchImageCaptureIntent() {
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (cameraIntent.resolveActivity(getPackageManager()) != null) {
File photoFile = null;
try {
photoFile = createImageFile();
} catch (IOException e) {
e.printStackTrace();
}
if (photoFile != null) {
Uri photoFileUri = FileProvider.getUriForFile(this, FILE_PROVIDER_AUTHORITY, photoFile);
Log.d(TAG, "dispatchImageCaptureIntent:photoFileUri: " + photoFile.toString());
cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoFileUri);
startActivityForResult(cameraIntent, CAMERA_RESULT);
}
}
}
@Override public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
@NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode) {
case CAMERA_PERMISSION_REQ_CODE:
if (grantResults[0] == PERMISSION_GRANTED) {
dispatchImageCaptureIntent();
} else {
Toast.makeText(this, "Required camera permission not granted", Toast.LENGTH_SHORT).show();
}
break;
case STORAGE_PERMISSION_REQ_CODE:
if (grantResults[0] == PERMISSION_GRANTED) {
dispatchGalleryIntent();
} else {
Toast.makeText(this, "Required storage permission not granted", Toast.LENGTH_SHORT)
.show();
}
break;
default:
throw new IllegalArgumentException("Unexpected request code");
}
}
private File createImageFile() throws IOException {
String timeStamp = DateFormat.getDateTimeInstance().format(new Date());
String imageFileName = "JPEG_" + timeStamp + "_";
File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
File image = File.createTempFile(imageFileName, ".jpg", storageDir);
mCapturedImagePath = image.getAbsolutePath();
return image;
}
private void setPic() {
// Get the dimensions of the View
int targetW = mImageView.getWidth();
int targetH = mImageView.getHeight();
// Get the dimensions of the bitmap
BitmapFactory.Options bmOptions = new BitmapFactory.Options();
bmOptions.inJustDecodeBounds = true;
BitmapFactory.decodeFile(mCapturedImagePath, bmOptions);
int photoW = bmOptions.outWidth;
int photoH = bmOptions.outHeight;
// Determine how much to scale down the image
int scaleFactor = Math.min(photoW/targetW, photoH/targetH);
// Decode the image file into a Bitmap sized to fill the View
bmOptions.inJustDecodeBounds = false;
bmOptions.inSampleSize = scaleFactor;
bmOptions.inPurgeable = true;
Bitmap bitmap = BitmapFactory.decodeFile(mCapturedImagePath, bmOptions);
mImageView.setImageBitmap(bitmap);
}
private Bundle uriToBundle(Uri imageUri) {
Bundle bundle = new Bundle();
bundle.putString(MainActivity.IMAGE_URI, imageUri.toString());
return bundle;
}
@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK) {
if (requestCode == GALLERY_RESULT) {
Uri imageUri = data.getData();
startActivity(MainActivity.getIntent(this, uriToBundle(Objects.requireNonNull(imageUri))));
} else if (requestCode == CAMERA_RESULT) {
File imageFile = new File(mCapturedImagePath);
Uri imageUri = Uri.fromFile(imageFile);
**mImageView.setImageURI(imageUri);** //**Line number 169**
startActivity(MainActivity.getIntent(this, uriToBundle((imageUri))));
}
} else {
Toast.makeText(this, "Image not loaded.", Toast.LENGTH_SHORT).show();
}
}
public static Intent getIntent(Context context) {
return new Intent(context, HomeActivity.class);
}
}
谁能告诉我如何解决这个问题?
提前致谢
发布于 2018-10-23 13:58:40
您正在使用mImageView而不初始化它会导致nullpointerexception。在代码周围放置一个try catch块,你会看到错误
https://stackoverflow.com/questions/-100002968
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