Question

我按照Android开发人员的指导使相机工作，但事件我不会忘记任何我有空例外

这是代码：

import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Date;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.widget.Toast;

public class MakePhotoActivity extends Activity {

public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;

/** Create a file Uri for saving an image or video */
private static Uri getOutputMediaFileUri(int type){
      return Uri.fromFile(getOutputMediaFile(type));
}

/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type){
    // To be safe, you should check that the SDCard is mounted
    // using Environment.getExternalStorageState() before doing this.

    File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
              Environment.DIRECTORY_PICTURES), "MyCameraApp");
    // This location works best if you want the created images to be shared
    // between applications and persist after your app has been uninstalled.

    // Create the storage directory if it does not exist
    if (! mediaStorageDir.exists()){
        if (! mediaStorageDir.mkdirs()){
            Log.d("MyCameraApp", "failed to create directory");
            return null;
        }else{
            Log.d("MyCameraApp", "success to create directory");
        }
    }

    // Create a media file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    File mediaFile;
    if (type == MEDIA_TYPE_IMAGE){
        mediaFile = new File(mediaStorageDir.getPath() + File.separator +
        "IMG_"+ timeStamp + ".jpg");
    } else if(type == MEDIA_TYPE_VIDEO) {
        mediaFile = new File(mediaStorageDir.getPath() + File.separator +
        "VID_"+ timeStamp + ".mp4");
    } else {
        return null;
    }

    return mediaFile;
}


private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE = 100;
private Uri fileUri;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.camera_tuto);

    // create Intent to take a picture and return control to the calling application
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

    fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE); // create a file to save the image
    intent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri); // set the image file name

    // start the image capture Intent
    startActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
        if (resultCode == RESULT_OK) {
            // Image captured and saved to fileUri specified in the Intent
            Toast.makeText(this, "Image saved to:\n" +
                     data.getData(), Toast.LENGTH_LONG).show();
        } else if (resultCode == RESULT_CANCELED) {
            // User cancelled the image capture
        } else {
            // Image capture failed, advise user
        }
    }
}

}

以下是拍照时的例外情况：

10-10 07:46:12.104: E/AndroidRuntime(1279): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=100, result=-1, data=null} to activity {com.example.android_app_test/com.example.android_app_test.MakePhotoActivity}: java.lang.NullPointerException

如何解决此问题

修改的 ** * *

这是错误的全文：

    10-10 09:02:50.434: D/AndroidRuntime(1735): Shutting down VM
10-10 09:02:50.434: W/dalvikvm(1735): threadid=1: thread exiting with uncaught exception (group=0x414c4700)
10-10 09:02:50.633: E/AndroidRuntime(1735): FATAL EXCEPTION: main
10-10 09:02:50.633: E/AndroidRuntime(1735): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=100, result=-1, data=null} to activity {com.example.android_app_test/com.example.android_app_test.MakePhotoActivity}: java.lang.NullPointerException
10-10 09:02:50.633: E/AndroidRuntime(1735):     at android.app.ActivityThread.deliverResults(ActivityThread.java:3367)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at android.app.ActivityThread.handleSendResult(ActivityThread.java:3410)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at android.app.ActivityThread.access$1100(ActivityThread.java:141)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1304)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at android.os.Looper.loop(Looper.java:137)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at android.app.ActivityThread.main(ActivityThread.java:5103)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at java.lang.reflect.Method.invokeNative(Native Method)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at java.lang.reflect.Method.invoke(Method.java:525)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at dalvik.system.NativeStart.main(Native Method)
10-10 09:02:50.633: E/AndroidRuntime(1735): Caused by: java.lang.NullPointerException
10-10 09:02:50.633: E/AndroidRuntime(1735):     at com.example.android_app_test.MakePhotoActivity.onActivityResult(MakePhotoActivity.java:88)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at android.app.Activity.dispatchActivityResult(Activity.java:5322)
10-10 09:02:50.633: E/AndroidRuntime(1735):     at android.app.ActivityThread.deliverResults(ActivityThread.java:3363)
10-10 09:02:50.633: E/AndroidRuntime(1735):     ... 11 more

camera在模拟器android应用程序中生成java.lang.null.pointer异常

0 个答案: