How to use cursorloader with kotlin

I am trying to convert java project to kotlin but one problem confused me.
Project structure:

App

: An application that is used to declare a global variable
MainActivity

: AppCompatActivity
Provider

: ContentProvider
SectionsPagerAdapter

: FragmentPagerAdapter
fragment0

:
fragment1

: fragment implements LoaderManager.LoaderCallbacks

When I try to convert chunk1 to kotlin it throws FC.
Snippet code 1:

class fragment1 : Fragment(), LoaderManager.LoaderCallbacks<Cursor> {
private var mMainView: View? = null
private var adapter: SimpleCursorAdapter? = null
private var cursor: Cursor? = null
private var date: Date? = null
private var kadaihao: Array<String?>? = null
private val uri: Uri? = null

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val inflater = activity.layoutInflater
    mMainView = inflater.inflate(R.layout.fragment1, activity.findViewById(R.id.container) as ViewGroup, false)
}

override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
                          savedInstanceState: Bundle?): View? {
    return mMainView
}

override fun onViewCreated(view: View?, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)

    val lv = mMainView!!.findViewById(R.id.lv1) as ListView
    val uiBindFrom = arrayOf("_id", "shuakae", "kadaihao", "shijian", "feilv", "beizhu")
    val uiBindTo = intArrayOf(R.id.ID1, R.id.tv_shuakae1, R.id.tv_kadaihao1, R.id.tv_shijian1, R.id.tv_feilv1, R.id.tv_beizhu1)
    loaderManager.initLoader(1, null, this)
    adapter = SimpleCursorAdapter(
            context, R.layout.item_zhangdan, null, uiBindFrom, uiBindTo,
            CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER)
    lv.adapter = adapter
}

override fun onCreateLoader(id: Int, args: Bundle): Loader<Cursor> {
    val projection = arrayOf("_id", "shuakae", "kadaihao", "shijian", "feilv", "beizhu")
    val selection = "yihuan=0"
    return CursorLoader(context, App.Uri_ZhangDan, projection, selection, null, "kadaihao asc,shijian desc")
}

override fun onLoadFinished(loader: Loader<Cursor>, data: Cursor) {
    adapter!!.swapCursor(data)
}

override fun onLoaderReset(loader: Loader<Cursor>) {
    adapter!!.swapCursor(null)
}
}

      

Try running it and throwing FC:

java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter args
at com.codeme.ccm.fragment1.onCreateLoader(fragment1.kt:0)
at android.support.v4.app.LoaderManagerImpl.createLoader(LoaderManager.java:539)
at android.support.v4.app.LoaderManagerImpl.createAndInstallLoader(LoaderManager.java:548)
at android.support.v4.app.LoaderManagerImpl.initLoader(LoaderManager.java:603)
at com.codeme.ccm.fragment1.onViewCreated(fragment1.kt:73)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1314)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1595)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:758)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2363)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2149)
at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2103)
at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:1984)
at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:626)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:143)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1268)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1116)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1642)
at android.view.View.measure(View.java:18811)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:714)
at android.support.design.widget.HeaderScrollingViewBehavior.onMeasureChild(HeaderScrollingViewBehavior.java:90)
at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1391)
at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:784)
at android.view.View.measure(View.java:18811)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
at android.view.View.measure(View.java:18811)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
at android.view.View.measure(View.java:18811)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.view.View.measure(View.java:18811)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
at android.view.View.measure(View.java:18811)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2643)
at android.view.View.measure(View.java:18811)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2127)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1243)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1479)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1134)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6050)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:860)
at android.view.Choreographer.doCallbacks(Choreographer.java:672)
at android.view.Choreographer.doFrame(Choreographer.java:608)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:846)
at android.os.Handler.handleCallback(Handler.java:742)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:5524)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:740)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:630)

      

How to solve it?

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1 answer


I haven't done much with CursorLoader in Android, but judging from the stack trace it looks like the Bundle argument might be null, but you declared it invalid, so Kotlin introduced some checks to check this for you.

Try to change

override fun onCreateLoader(id: Int, args: Bundle)

      



to

override fun onCreateLoader(id: Int, args: Bundle?)

      

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