分享图片 Android nullPointerException

Question

我正在尝试与 android 共享图像，我在 resId 中恢复图像资源，然后在 shareImage 方法中使用它。 class 代码是这样的：

public class SinglePhotoActivity extends AppCompatActivity {
    ImageView singlePhoto;
    String image;
    Button shareButton;
    DBHelper db;
    Integer userId;
    DrawerLayout drawerLayout;
    private Context context;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_single_photo);
        singlePhoto = (ImageView) findViewById(R.id.singlePhoto);
        shareButton = (Button) findViewById(R.id.btn_share);
        userId = Utils.USER.getID();
        drawerLayout = findViewById(R.id.drawer_layout);
        db = new DBHelper(this);
        this.context = context;
        //Set menu
        TextView nome = (TextView) findViewById(R.id.menuName);
        nome.setText(Utils.USER.getNAME() + " " + Utils.USER.getLASTNAME());
        if (Utils.USER.getPROFILEPHOTO() != "") {
            Bitmap bitmapProfile = ProfileImage.StringToBitMap(Utils.USER.getPROFILEPHOTO());
            ImageView profileMenu = (ImageView) findViewById(R.id.menuProfileImage);
            profileMenu.setImageBitmap(bitmapProfile);
        }

        //Recupero nome immagine e la mostro
        image = getIntent().getStringExtra("imageName");
        final int resID = getResources().getIdentifier(image, "drawable", getPackageName());

        singlePhoto.setImageResource(resID);

        shareButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                shareImage(getParent(), resID);
            }
        });
    }

    public static void shareImage(Activity context, Integer resource_id) {
        Bitmap b = BitmapFactory.decodeResource(context.getResources(), resource_id);
        Intent share = new Intent(Intent.ACTION_SEND);
        share.setType("image/jpeg");
        ByteArrayOutputStream bytes = new ByteArrayOutputStream();
        b.compress(Bitmap.CompressFormat.JPEG, 100, bytes);
        String path = MediaStore.Images.Media.insertImage(context.getContentResolver(), b, "Title", null);
        Uri imageUri = Uri.parse(path);
        share.putExtra(Intent.EXTRA_STREAM, imageUri);
        context.startActivity(Intent.createChooser(share, "Select"));
    }}

但不起作用。我尝试了不同的上下文并更改了 shareImage 签名中上下文中的 activity 类型，但问题仍然存在。我有这个错误。

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.myapplication, PID: 23199
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapplication/com.example.myapplication.SinglePhotoActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
        at com.example.myapplication.SinglePhotoActivity.onCreate(SinglePhotoActivity.java:69)
        at android.app.Activity.performCreate(Activity.java:7802)
        at android.app.Activity.performCreate(Activity.java:7791)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1299)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) 
        at android.os.Handler.dispatchMessage(Handler.java:107) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7356) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

我无法解决问题并使其全部正常工作。我必须改变上下文吗？还是我错了什么？

Answer 1

改变

shareImage(getParent(), resID);

至

shareImage(SinglePhotoActivity.this, resID);

分享图片 Android nullPointerException

Share Image Android nullPointerException

java

android

nullpointerexception

android-context