参见英文答案 > What is a NullPointerException,and how do I fix it?12个
我想点击按钮后拍照.但是当我尝试使用FileProvider获取URI时,我得到NullPointerException.

这是我的ErrorCode：

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.XmlResourceParser android.content.pm.PackageItemInfo.loadXmlMetaData(android.content.pm.PackageManager,java.lang.String)' on a null object reference
        at android.support.v4.content.FileProvider.parsePathStrategy(FileProvider.java:583)
    at android.support.v4.content.FileProvider.getPathStrategy(FileProvider.java:557)
    at android.support.v4.content.FileProvider.getUriForFile(FileProvider.java:399)

    at ibas.orosol.BildActivity.takePicture(BildActivity.java:86)
    at java.lang.reflect.Method.invoke(Native Method)
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
    at android.view.View.performClick(View.java:5637)
    at android.view.View$PerformClick.run(View.java:22429)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6119)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

问题线似乎是：

mUri = FileProvider.getUriForFile(getApplication().getApplicationContext(),"ibas.provider",file);

这是我的代码：

public void takePicture(View view) throws IOException {

    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    try{
        File file =  createImageFile();

        mUri = FileProvider.getUriForFile(getApplication().getApplicationContext(),file);
        intent.putExtra(MediaStore.EXTRA_OUTPUT,mUri);
        startActivityForResult(intent,REQUEST_IMAGE_CAPTURE);
    } catch (IOException e){
        e.printStackTrace();
    }

}


private File createImageFile() throws IOException {

    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM);
    File image = File.createTempFile(
            imageFileName,/* prefix */
            ".jpg",/* suffix */
            storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    mCurrentPhotoPath = "file:" + image.getAbsolutePath();
    return image;
}

@Override
protected void onActivityResult(int requestCode,int resultCode,Intent data) {

    String path = "sdcard/orosol/captured_image.jpg";
    if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == Activity.RESULT_OK) {
        Log.i("uri-data","Uri: " + mUri.toString());


        mBitmap = getBitmapFromUri(mImageView,BildActivity.this,mUri);


        mImageView.setImageBitmap(mBitmap);
        mImageView.setScaleType(ImageView.ScaleType.CENTER_CROP);

    }

}

我的清单：

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="ibas.orosol">

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CALL_PHONE" />

<uses-feature
    android:name="android.hardware.camera"
    android:required="false" />

<provider
    android:name="android.support.v4.content.FileProvider"
    android:authorities="ibas.provider"
    android:exported="false"
    android:grantUriPermissions="true">
    <Meta-data
        android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/provider_paths" />
</provider>

<!--
     The ACCESS_COARSE/FINE_LOCATION permissions are not required to use
     Google Maps Android API v2,but you must specify either coarse or fine
     location permissions for the 'MyLocation' functionality. 
-->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/Theme.AppCompat.NoActionBar">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".MenuActivity" />
    <activity
        android:name=".HeizoelActivity"
        android:theme="@style/AppTheme">
        <Meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value=".MenuActivity" />
    </activity>
    <activity
        android:name=".BildActivity"
        android:theme="@style/AppTheme">
        <Meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value=".MenuActivity" />
        >
    </activity>
    <activity
        android:name=".FacebookActivity"
        android:theme="@style/AppTheme">
        <Meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value=".MenuActivity" />
    </activity>
    <!--
         The API key for Google Maps-based APIs is defined as a string resource.
         (See the file "res/values/google_maps_api.xml").
         Note that the API key is linked to the encryption key used to sign the APK.
         You need a different API key for each encryption key,including the release key that is used to
         sign the APK for publishing.
         You can define the keys for the debug and release targets in src/debug/ and src/release/. 
    -->
    <Meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="@string/google_maps_key" />

    <activity
        android:name=".KontakteActivity"
        android:theme="@style/AppTheme">
        <Meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value=".MenuActivity" />
    </activity>
    <activity android:name=".UeberUnsActivity"
        android:theme="@style/AppTheme">
        <Meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value=".MenuActivity" />
    </activity>
</application>

res / xml中的提供者

<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-path name="external_files" path="."/> </paths>

发生问题的任何想法？

<provider
    android:name="android.support.v4.content.FileProvider"
    android:authorities="ibas.provider"
    android:exported="false"
    android:grantUriPermissions="true">
    <Meta-data
        android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/provider_paths" />
</provider>