我有一个简单的活动，当点击按钮时，图片被设置为ImageView。
当我打开相机并拍照时，它很好，图片被加载到ImageView。 但是如果我通过按钮打开相机应用程序，并取消（按后退按钮），则应用程序崩溃。 我想知道如何解决它。提前谢谢。
活动
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Date;
public class SituationStatusActivity extends AppCompatActivity {
ImageView imVCature_pic_first;
private static final int REQUEST_CODE = 1;
private Bitmap bitmap;
private ImageView imageView;
static final int REQUEST_IMAGE_CAPTURE = 1;
String imageFilePath;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_situation_status);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
overridePendingTransition(R.anim.fadein, R.anim.fadeout);
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
imageFilePath = Environment.getExternalStorageDirectory().toString()+"/Android/data/com.my.app/Image-"+timeStamp+".png";
imVCature_pic_first = (ImageView) findViewById(R.id.nirPic);
Button uploadPic = (Button) findViewById(R.id.picUploadButton);
uploadPic.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) { /*************************** Camera Intent Start ************************/
File imageFile = new File(imageFilePath);
Uri imageFileUri = Uri.fromFile(imageFile); // convert path to Uri
// Standard Intent action that can be sent to have the camera
// application capture an image and return it.
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageFileUri); // set the image file name
startActivityForResult(intent, 1);
/*************************** Camera Intent End ************************/
}
});
}
public void onActivityResult( int requestCode, int resultCode, Intent data){
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1) {
BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
bmpFactoryOptions.inJustDecodeBounds = false;
//imageFilePath image path which you pass with intent
Bitmap bp = BitmapFactory.decodeFile(imageFilePath, bmpFactoryOptions);
//rotate image by 90 degrees
Matrix rotateMatrix = new Matrix();
rotateMatrix.postRotate(270);
Bitmap rotatedBitmap = Bitmap.createBitmap(bp, 0, 0, bp.getWidth(), bp.getHeight(), rotateMatrix, false);
imVCature_pic_first.setImageBitmap(getRoundedCornerBitmap(rotatedBitmap,500));
imVCature_pic_first.setScaleType(ImageView.ScaleType.FIT_XY);
} else {
Toast.makeText(getApplicationContext(),"not taken", Toast.LENGTH_LONG).show();
}
}
public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, int pixels) {
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap
.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
final RectF rectF = new RectF(rect);
final float roundPx = pixels;
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
return output;
}
}
LogCat错误
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=0, data=null} to activity {fastner.israel.nir_zabari.onelove/fastner.israel.nir_zabari.onelove.SituationStatusActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.graphics.Bitmap.getWidth()' on a null object reference
at android.app.ActivityThread.deliverResults(ActivityThread.java:3688)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3731)
at android.app.ActivityThread.access$1300(ActivityThread.java:162)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1398)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5430)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:913)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:706)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.graphics.Bitmap.getWidth()' on a null object reference
at fastner.israel.nir_zabari.onelove.SituationStatusActivity.onActivityResult(SituationStatusActivity.java:83)
at android.app.Activity.dispatchActivityResult(Activity.java:6299)
at android.app.ActivityThread.deliverResults(ActivityThread.java:3684)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3731)
at android.app.ActivityThread.access$1300(ActivityThread.java:162)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1398)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5430)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:913)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:706)
答案 0 :(得分：2)
您需要检查resultCode以及requestCode取消相机，您将在onActivityResult
将您的代码更改为：
public void onActivityResult( int requestCode, int resultCode, Intent data){
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1 && resultCode == RESULT_OK) {
BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
bmpFactoryOptions.inJustDecodeBounds = false;
//imageFilePath image path which you pass with intent
Bitmap bp = BitmapFactory.decodeFile(imageFilePath, bmpFactoryOptions);
//rotate image by 90 degrees
Matrix rotateMatrix = new Matrix();
rotateMatrix.postRotate(270);
Bitmap rotatedBitmap = Bitmap.createBitmap(bp, 0, 0, bp.getWidth(), bp.getHeight(), rotateMatrix, false);
imVCature_pic_first.setImageBitmap(getRoundedCornerBitmap(rotatedBitmap,500));
imVCature_pic_first.setScaleType(ImageView.ScaleType.FIT_XY);
} else {
Toast.makeText(getApplicationContext(),"not taken", Toast.LENGTH_LONG).show();
}
}
PS：尽量避免对requestCode使用硬编码值，将其声明为常量变量。
答案 1 :(得分：0)
在onActivityResult方法中，检查requestCode后检查resultCode。如果您从相机接受图像，resultCode将返回RESULT_OK，如果您没有接受来自相机的图像，则返回RESULT_CANCEL。在您的情况下，您不接受来自摄像机的任何图像并返回活动，因此resultCode将为RESULT_CANCEL。如果您不检查resultCode的条件，则应用程序将崩溃。
public void onActivityResult( int requestCode, int resultCode, Intent data){
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1) {
if (resultCode == RESULT_OK) {
BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
bmpFactoryOptions.inJustDecodeBounds = false;
//imageFilePath image path which you pass with intent
Bitmap bp = BitmapFactory.decodeFile(imageFilePath, bmpFactoryOptions);
//rotate image by 90 degrees
Matrix rotateMatrix = new Matrix();
rotateMatrix.postRotate(270);
Bitmap rotatedBitmap = Bitmap.createBitmap(bp, 0, 0, bp.getWidth(), bp.getHeight(), rotateMatrix, false);
imVCature_pic_first.setImageBitmap(getRoundedCornerBitmap(rotatedBitmap,500));
imVCature_pic_first.setScaleType(ImageView.ScaleType.FIT_XY);
}
else{
// your code in cancel condition
}
} else {
Toast.makeText(getApplicationContext(),"not taken", Toast.LENGTH_LONG).show();
}
}