"Attempt to get length of null array" 许可 运行 时间
"Attempt to get length of null array" on Permission run time
我在 运行我的基本 运行 时间许可项目中遇到了一些问题。
这是我的代码：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Initializing button
buttonRequestPermission = (Button) findViewById(R.id.buttonRequestPermission);
//Adding a click listener
buttonRequestPermission.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//First checking if the app is already having the permission
if (isReadStorageAllowed()) {
//If permission is already having then showing the toast
Toast.makeText(MainActivity.this, "You already have the permission", Toast.LENGTH_LONG).show();
//Existing the method with return
return;
}
//If the app has not the permission then asking for the permission
requestStoragePermission();
}
});
}
//We are calling this method to check the permission status
private boolean isReadStorageAllowed() {
//Getting the permission status
int result = ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
//If permission is granted returning true
if (result == PackageManager.PERMISSION_GRANTED)
return true;
//If permission is not granted returning false
return false;
}
public void requestStoragePermission() {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.READ_EXTERNAL_STORAGE)) {
}
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, STORAGE_PERMISSION_CODE);
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
//Checking the request code of our request
if (requestCode == STORAGE_PERMISSION_CODE) {
//If permission is granted
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
//Displaying a toast
Toast.makeText(this, "Permission granted now you can read the storage", Toast.LENGTH_LONG).show();
} else {
//Displaying another toast if permission is not granted
Toast.makeText(this, "Oops you just denied the permission", Toast.LENGTH_LONG).show();
}
}
}
在这个函数中，程序似乎在requestPermissions()函数中崩溃了。
当我在设备上测试应用程序时，应用程序崩溃并且 returns "Unfortunately, Package installation has stopped"。然后给我这个 logcat 错误：
Process: com.google.android.packageinstaller, PID: 17894
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.google.android.packageinstaller/com.android.packageinstaller.permission.ui.GrantPermissionsActivity}: java.lang.NullPointerException: Attempt to get length of null array
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2477)
at android.app.ActivityThread.access0(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5418)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to get length of null array
at com.android.packageinstaller.permission.ui.GrantPermissionsActivity.computePermissionGrantState(GrantPermissionsActivity.java:312)
at com.android.packageinstaller.permission.ui.GrantPermissionsActivity.updateDefaultResults(GrantPermissionsActivity.java:362)
at com.android.packageinstaller.permission.ui.GrantPermissionsActivity.onCreate(GrantPermissionsActivity.java:105)
at android.app.Activity.performCreate(Activity.java:6285)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2370)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2477)
at android.app.ActivityThread.access0(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5418)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
我也将其放入清单文件中：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.angelos.permissiontest">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
</manifest>
我不太确定为什么会这样。这应该是一个超级简单的项目。有人可以帮助我吗？
public void requestStoragePermission() {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.READ_EXTERNAL_STORAGE)) {
// add the below line here
ActivityCompat.requestPermissions(this, new String[]{
Manifest.permission.READ_EXTERNAL_STORAGE}, STORAGE_PERMISSION_CODE);
}
// ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.READ_EXTERNAL_STORAGE}, STORAGE_PERMISSION_CODE);
}
make below changes to to avoid crash
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
替换为下一行
if(grantResults != null && grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
这个java.lang.NullPointerException不是因为你的代码。它变成了com.android.packageinstaller.permission.ui.GrantPermissionsActivity.java。以下是您获得 java.lang.NullPointerException
的代码
309 private int computePermissionGrantState(PackageInfo callingPackageInfo,
310 String permission, int permissionPolicy) {
311 boolean permissionRequested = false;
312
313 for (int i = 0; i < callingPackageInfo.requestedPermissions.length; i++) {
314 .....
346 }
在你的例子中，callingPackageInfo.requestedPermissions 是 null。因此，请检查您是否将请求的权限声明为正确的清单。
这里的答案解决了@greenapps 和@Pankaj Kuma 所建议的问题：
将 Permission 标签放在清单中的应用程序标签之外：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.angelos.permissiontest">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
参考：developer.android.com/training/permissions/declaring.html
我在 运行我的基本 运行 时间许可项目中遇到了一些问题。
这是我的代码：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Initializing button
buttonRequestPermission = (Button) findViewById(R.id.buttonRequestPermission);
//Adding a click listener
buttonRequestPermission.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//First checking if the app is already having the permission
if (isReadStorageAllowed()) {
//If permission is already having then showing the toast
Toast.makeText(MainActivity.this, "You already have the permission", Toast.LENGTH_LONG).show();
//Existing the method with return
return;
}
//If the app has not the permission then asking for the permission
requestStoragePermission();
}
});
}
//We are calling this method to check the permission status
private boolean isReadStorageAllowed() {
//Getting the permission status
int result = ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
//If permission is granted returning true
if (result == PackageManager.PERMISSION_GRANTED)
return true;
//If permission is not granted returning false
return false;
}
public void requestStoragePermission() {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.READ_EXTERNAL_STORAGE)) {
}
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, STORAGE_PERMISSION_CODE);
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
//Checking the request code of our request
if (requestCode == STORAGE_PERMISSION_CODE) {
//If permission is granted
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
//Displaying a toast
Toast.makeText(this, "Permission granted now you can read the storage", Toast.LENGTH_LONG).show();
} else {
//Displaying another toast if permission is not granted
Toast.makeText(this, "Oops you just denied the permission", Toast.LENGTH_LONG).show();
}
}
}
在这个函数中，程序似乎在requestPermissions()函数中崩溃了。
当我在设备上测试应用程序时，应用程序崩溃并且 returns "Unfortunately, Package installation has stopped"。然后给我这个 logcat 错误：
Process: com.google.android.packageinstaller, PID: 17894
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.google.android.packageinstaller/com.android.packageinstaller.permission.ui.GrantPermissionsActivity}: java.lang.NullPointerException: Attempt to get length of null array
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2477)
at android.app.ActivityThread.access0(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5418)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to get length of null array
at com.android.packageinstaller.permission.ui.GrantPermissionsActivity.computePermissionGrantState(GrantPermissionsActivity.java:312)
at com.android.packageinstaller.permission.ui.GrantPermissionsActivity.updateDefaultResults(GrantPermissionsActivity.java:362)
at com.android.packageinstaller.permission.ui.GrantPermissionsActivity.onCreate(GrantPermissionsActivity.java:105)
at android.app.Activity.performCreate(Activity.java:6285)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2370)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2477)
at android.app.ActivityThread.access0(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5418)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
我也将其放入清单文件中：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.angelos.permissiontest">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
</manifest>
我不太确定为什么会这样。这应该是一个超级简单的项目。有人可以帮助我吗？
public void requestStoragePermission() {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.READ_EXTERNAL_STORAGE)) {
// add the below line here
ActivityCompat.requestPermissions(this, new String[]{
Manifest.permission.READ_EXTERNAL_STORAGE}, STORAGE_PERMISSION_CODE);
}
// ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.READ_EXTERNAL_STORAGE}, STORAGE_PERMISSION_CODE);
}
make below changes to to avoid crash
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
替换为下一行
if(grantResults != null && grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
这个java.lang.NullPointerException不是因为你的代码。它变成了com.android.packageinstaller.permission.ui.GrantPermissionsActivity.java。以下是您获得 java.lang.NullPointerException
309 private int computePermissionGrantState(PackageInfo callingPackageInfo,
310 String permission, int permissionPolicy) {
311 boolean permissionRequested = false;
312
313 for (int i = 0; i < callingPackageInfo.requestedPermissions.length; i++) {
314 .....
346 }
在你的例子中，callingPackageInfo.requestedPermissions 是 null。因此，请检查您是否将请求的权限声明为正确的清单。
这里的答案解决了@greenapps 和@Pankaj Kuma 所建议的问题：
将 Permission 标签放在清单中的应用程序标签之外：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.angelos.permissiontest">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
参考：developer.android.com/training/permissions/declaring.html