我已经制作了一个简单的Android应用程序，因为我想要捕获一张图片，并希望将其设置为一个imageview，但它在onActivityResult中给我空指针异常，我的logcattrace和代码如下： 的码
public void onClick(DialogInterface dialog, int item) {
if (options[item].equals("Take Photo"))
{
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
File f = new File(android.os.Environment.getExternalStorageDirectory(), "temp.jpg");
intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(f));
startActivityForResult(intent, 1);
}
...
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == RESULT_OK) {
if (requestCode == SELECT_PICTURE) {
Uri selectedImageUri = data.getData();
if (Build.VERSION.SDK_INT < 19) {
Log.i("Your version Build.VERSION.SDK_INT < 19","if condition");//<19
selectedImagePath = getPath(selectedImageUri);
bitmap_selected_image2 = BitmapFactory.decodeFile(selectedImagePath);
v_iv_photo_main.setImageBitmap(bitmap_selected_image2);
// finish();
// startActivity(new Intent(SelectPhotoCountryActivity.this,SetPhotoFrameActivity.class));
}
logcat的
06-16 14:34:15.564: E/AndroidRuntime(31301): FATAL EXCEPTION: main
06-16 14:34:15.564: E/AndroidRuntime(31301): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=null} to activity {com.example.footballapp/com.example.footballapp.SelectPhotoCountryActivity}: java.lang.NullPointerException
06-16 14:34:15.564: E/AndroidRuntime(31301): at android.app.ActivityThread.deliverResults(ActivityThread.java:3518)
06-16 14:34:15.564: E/AndroidRuntime(31301): at android.app.ActivityThread.handleSendResult(ActivityThread.java:3561)
06-16 14:34:15.564: E/AndroidRuntime(31301): at android.app.ActivityThread.access$1200(ActivityThread.java:168)
06-16 14:34:15.564: E/AndroidRuntime(31301): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1377)
06-16 14:34:15.564: E/AndroidRuntime(31301): at android.os.Handler.dispatchMessage(Handler.java:99)
06-16 14:34:15.564: E/AndroidRuntime(31301): at android.os.Looper.loop(Looper.java:176)
06-16 14:34:15.564: E/AndroidRuntime(31301): at android.app.ActivityThread.main(ActivityThread.java:5493)
06-16 14:34:15.564: E/AndroidRuntime(31301): at java.lang.reflect.Method.invokeNative(Native Method)
06-16 14:34:15.564: E/AndroidRuntime(31301): at java.lang.reflect.Method.invoke(Method.java:525)
06-16 14:34:15.564: E/AndroidRuntime(31301): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1225)
06-16 14:34:15.564: E/AndroidRuntime(31301): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1041)
06-16 14:34:15.564: E/AndroidRuntime(31301): at dalvik.system.NativeStart.main(Native Method)
06-16 14:34:15.564: E/AndroidRuntime(31301): Caused by: java.lang.NullPointerException
06-16 14:34:15.564: E/AndroidRuntime(31301): at com.example.footballapp.SelectPhotoCountryActivity.onActivityResult(SelectPhotoCountryActivity.java:281)
06-16 14:34:15.564: E/AndroidRuntime(31301): at android.app.Activity.dispatchActivityResult(Activity.java:5563)
06-16 14:34:15.564: E/AndroidRuntime(31301): at android.app.ActivityThread.deliverResults(ActivityThread.java:3514)
06-16 14:34:15.564: E/AndroidRuntime(31301): ... 11 more
答案 0 :(得分：0)
package edu.gvsu.cis.masl.camerademo;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
public class MyCameraActivity extends Activity {
private static final int CAMERA_REQUEST = 1888;
private ImageView imageView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
this.imageView = (ImageView)this.findViewById(R.id.imageView1);
Button photoButton = (Button) this.findViewById(R.id.button1);
photoButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) { /* create an instance of intent
* pass action android.media.action.IMAGE_CAPTURE
* as argument to launch camera
*/
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
/*create instance of File with name img.jpg*/
File file = new File(Environment.getExternalStorageDirectory()+File.separator + "img.jpg");
/*put uri as extra in intent object*/
intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(file));
/*start activity for result pass intent as argument and request code */
startActivityForResult(intent, 1)
}
});
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {super.onActivityResult(requestCode, resultCode, data);
//if request code is same we pass as argument in startActivityForResult
if(requestCode==1){
//create instance of File with same name we created before to get image from storage
File file = new File(Environment.getExternalStorageDirectory()+File.separator + "img.jpg");
//get bitmap from path with size of
imVCature_pic.setImageBitmap(decodeSampledBitmapFromFile(file.getAbsolutePath(), 600, 450));
}
}
public static Bitmap decodeSampledBitmapFromFile(String path,
int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
//Query bitmap without allocating memory
options.inJustDecodeBounds = true;
//decode file from path
BitmapFactory.decodeFile(path, options);
// Calculate inSampleSize
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
//decode according to configuration or according best match
options.inPreferredConfig = Bitmap.Config.RGB_565;
int inSampleSize = 1;
if (height > reqHeight) {
inSampleSize = Math.round((float)height / (float)reqHeight);
}
int expectedWidth = width / inSampleSize;
if (expectedWidth > reqWidth) {
//if(Math.round((float)width / (float)reqWidth) > inSampleSize) // If bigger SampSize..
inSampleSize = Math.round((float)width / (float)reqWidth);
}
//if value is greater than 1,sub sample the original image
options.inSampleSize = inSampleSize;
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeFile(path, options);
}
}
}