从Android版本棉花糖开始，如何请求从Android拨打电话的权限？

Question

我正在尝试通过Android拨打电话，并且还设置了运行时权限。并且询问是否允许拨打电话。但是，当我按允许时，应用程序崩溃：

这是我的实现方式：

private static final int REQUEST_PHONE_CALL = 1;
Intent intent = new Intent(Intent.ACTION_CALL, Uri.parse("tel:" + "[phone]"));

if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
    if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CALL_PHONE) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CALL_PHONE},REQUEST_PHONE_CALL);
    }
    else
    {
        startActivity(intent);
    }
}
else
{
    startActivity(intent);
}






@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case REQUEST_PHONE_CALL: {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                startActivity(intent);
            }
            else
            {

            }
            return;
        }
    }
}

这是我在logcat中获得的：

java.lang.RuntimeException: Failure delivering result ResultInfo{who=@android:requestPermissions:, 
     request=1, result=-1, data=Intent { act=android.content.pm.action.REQUEST_PERMISSIONS (has extras) }} 
     to activity {com.devpost.airway/com.devpost.airway.activities.MainActivity}: 
     java.lang.NullPointerException: Attempt to invoke virtual method 
     'java.lang.String android.content.Intent.toString()' on a null object reference

      at android.app.ActivityThread.deliverResults(ActivityThread.java:3733)
      at android.app.ActivityThread.handleSendResult(ActivityThread.java:3776)
      at android.app.ActivityThread.-wrap16(ActivityThread.java)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1412)
      at android.os.Handler.dispatchMessage(Handler.java:102)
      at android.os.Looper.loop(Looper.java:148)
      at android.app.ActivityThread.main(ActivityThread.java:5461)
      at java.lang.reflect.Method.invoke(Native Method)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 
    'java.lang.String android.content.Intent.toString()' on a null object reference
      at android.app.Instrumentation.execStartActivity(Instrumentation.java:1485)
      at android.app.Activity.startActivityForResult(Activity.java:3930)
      at android.support.v4.app.BaseFragmentActivityJB.startActivityForResult(BaseFragmentActivityJB.java:48)
      at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:75)
      at android.app.Activity.startActivityForResult(Activity.java:3890)
      at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:856)
      at android.app.Activity.startActivity(Activity.java:4213)
      at android.app.Activity.startActivity(Activity.java:4181)
      at com.devpost.airway.activities.MainActivity.onRequestPermissionsResult(MainActivity.java:140)
      at android.app.Activity.dispatchRequestPermissionsResult(Activity.java:6582)
      at android.app.Activity.dispatchActivityResult(Activity.java:6460)
      at android.app.ActivityThread.deliverResults(ActivityThread.java:3729)
      at android.app.ActivityThread.handleSendResult(ActivityThread.java:3776) 
      at android.app.ActivityThread.-wrap16(ActivityThread.java) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1412) 
      at android.os.Handler.dispatchMessage(Handler.java:102) 
      at android.os.Looper.loop(Looper.java:148) 
      at android.app.ActivityThread.main(ActivityThread.java:5461) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

是什么原因造成的？

Answer 1

堆栈跟踪似乎表明您的权限流工作正常，但是对startActivityfrom
的调用onRequestPermissionsResult()崩溃了。是Intent你传递到startActivity设置是否正确？我看不到在代码的那部分中设置了它。

另请注意，它ContextCompat.checkSelfPermission可以代表您处理SDK版本检查，因此您应该可以使用

if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CALL_PHONE) != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CALL_PHONE},REQUEST_PHONE_CALL);
}
else
{
    startActivity(intent);
}

本身，没有包装的SDK版本检查代码。