您好我是新来的Android开发。林与Android科特林工作。我要检查是否有内容提供商的任何数据。这是我在mainactivity尝试示例代码
class MainActivity : AppCompatActivity() {
companion object {
val AUTHORITY = "com.wsample.moblity.auth"
val CONTENT_URI = Uri.parse("content://$AUTHORITY")
}
var c:Cursor? = contentResolver.query(CONTENT_URI, null, null, null, null)
override fun onCreate(savedInstanceState: Bundle?) {
if (c!!.count != 0) {
Log.d("COUNT", "NOT ZERO")
} else {
Log.d("COUNT 1", "ZERO")
}
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
}
但我发现了一个异常喜欢,
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.ContentResolver android.content.Context.getContentResolver()' on a null object reference
请帮我解决一下这个。
推动这一行成的onCreate功能
变种C:光标? = contentResolver.query(CONTENT_URI,NULL,NULL,NULL,NULL)