Java – Android and C: necessary?

It's just very simple to check Android development. It seems that most people are using Java. However

Does this mean that in Android applications, using Java and using C:

>Sometimes? > Many? > Almost never? > Never: you can't use it for applications?

resolvent:

Sometimes, as far as possible, only time sensitive code, even so, it may not be a good solution. The standard method of making Android applications is Java. This is because java code will really realize cross platform and can run on almost all devices. Although as far as I know, NDK only supports ARM processors, it will not be fully encouraged unless absolutely necessary

Many people abuse NDK to avoid using Java or SDK. This is wrong