Android: Display Image from SD CARD

问题

This is driving me insane! Here\'s my code (I know this file exists):

File imageFile = new File(\"/sdcard/gallery_photo_4.jpg\");
ImageView jpgView = (ImageView)findViewById(R.id.imageView);
BitmapDrawable d = new BitmapDrawable(getResources(), imageFile.getAbsolutePath());
jpgView.setImageDrawable(d);

The error occurs on that last line (line 28, referenced below).

Error output:

W/dalvikvm(  865): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
E/AndroidRuntime(  865): FATAL EXCEPTION: main
E/AndroidRuntime(  865): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.example.camera/org.example.camera.Imgview}: java.lang.NullPointerException
E/AndroidRuntime(  865):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
E/AndroidRuntime(  865):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
E/AndroidRuntime(  865):    at android.app.ActivityThread.access$2300(ActivityThread.java:125)
E/AndroidRuntime(  865):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
E/AndroidRuntime(  865):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(  865):    at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(  865):    at android.app.ActivityThread.main(ActivityThread.java:4627)
E/AndroidRuntime(  865):    at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(  865):    at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime(  865):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
E/AndroidRuntime(  865):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
E/AndroidRuntime(  865):    at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(  865): Caused by: java.lang.NullPointerException
E/AndroidRuntime(  865):    at org.example.camera.Imgview.onCreate(Imgview.java:28)
E/AndroidRuntime(  865):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
E/AndroidRuntime(  865):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
E/AndroidRuntime(  865):    ... 11 more
W/ActivityManager(   59):   Force finishing activity org.example.camera/.Imgview

My layout looks like (probably not necessary):

<LinearLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
android:orientation=\"vertical\" android:layout_width=\"fill_parent\"
android:layout_height=\"fill_parent\">
<ImageView android:id=\"@+id/imageView\" android:layout_width=\"fill_parent\"
android:layout_height=\"fill_parent\" android:scaleType=\"center\">
</ImageView>
</LinearLayout>

Thank you very much for any help.

回答1:

I would rather use a BitmapFactory to decode the Image from the file-path:

Bitmap bitmap = BitmapFactory.decodeFile(imageFile.getAbsolutePath());
jpgView.setImageBitmap(bitmap);

The Docs say:

If the specified file name is null, or cannot be decoded into a bitmap, the function returns null.

Can you check if the code works with another image and if you can open your image on your PC thought. Maybe the file is corrupt.

回答2:

This code worked for me finally:

    setContentView(R.layout.main);
    ImageView jpgView = (ImageView)findViewById(R.id.imageView);
    Bitmap bitmap = BitmapFactory.decodeFile("/sdcard/sample-1.jpg");
    jpgView.setImageBitmap(bitmap);

Crash was happening because setContentView() was not performed before attaching the jpgview:

code that was crashing:

    ImageView jpgView = (ImageView)findViewById(R.id.imageView);
    Bitmap bitmap = BitmapFactory.decodeFile("/sdcard/sample-1.jpg");
    jpgView.setImageBitmap(bitmap);
    setContentView(R.layout.main);

回答3:

String imagePath = Environment.getExternalStorageDirectory().toString() + PATH_TO_IMAGE;
return Drawable.createFromPath(imagePath)

回答4:

USE THIS LINE OF CODE FOR GETTING IMAGE FROM SDCARD. AND THEN DISPLAY IT IN YOUR IMAGEVIEW

where "FileInputOutput" is a folder in your sdcard

    String path = Environment.getExternalStorageDirectory()+ "/FileInputOutput/img1.jpg"; 
            File imgFile = new File(path);
            if(imgFile.exists())
        {
                Bitmap myBitmap = BitmapFactory.decodeFile(imgFile.getAbsolutePath());                  
                ImageView myImage = (ImageView) findViewById(R.id.imageView1);
                myImage.setImageBitmap(myBitmap);
        }
            else                    
                Toast.makeText(v.getContext(),"no IMAGE IS PRESENT'",Toast.LENGTH_SHORT).show();
        }

来源：https://stackoverflow.com/questions/6725718/android-display-image-from-sd-card