Kotlin内部类无法启动Session对象

时间：2018-12-03 08:56:25

标签： android kotlin inner-classes 

    import android.content.Context
import android.graphics.Color
import android.net.Uri
import android.support.design.widget.TabLayout
import android.support.v4.app.Fragment
import android.support.v4.app.FragmentManager
import android.support.v4.app.FragmentPagerAdapter
import android.support.v4.view.ViewPager
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.LayoutInflater
import android.widget.TextView
import android.widget.Toolbar
import java.util.ArrayList
import com.salesrep.auxxa.alliontechnologies.auxxasr.R.id.viewPager

import android.graphics.drawable.GradientDrawable
import android.support.v4.app.FragmentStatePagerAdapter
import android.support.v4.view.PagerAdapter
import android.util.Log
import com.salesrep.auxxa.alliontechnologies.auxxasr.utillities.Session
import org.json.JSONObject


class NewPaymentActivity : AppCompatActivity(),SummaryFragment.OnFragmentInteractionListener,ReceiptDetailsFragment.OnFragmentInteractionListener{

    internal lateinit var viewpageradapter: ViewPagerAdapter //Declare PagerAdapter

    private var tabLayout: TabLayout? = null
    var viewPager: ViewPager? = null
    var toolbar: Toolbar? = null
    var myPreference : Session? =null

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_new_payment)
        myPreference= Session(this)
        viewpageradapter= ViewPagerAdapter(supportFragmentManager)

        viewPager = findViewById(R.id.viewPager) as ViewPager
        setupViewPager(viewPager!!)

        tabLayout = findViewById(R.id.tab_layout) as TabLayout
        tabLayout!!.setupWithViewPager(viewPager)

//      tabLayout!!.setSelectedTabIndicatorColor(getResources().getColor(R.color.t));
        tabLayout!!.setSelectedTabIndicatorHeight(0)




        val headerView = (getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater)
                .inflate(R.layout.custom_tabs_for_payments, null, false)

        val receiptDetails = headerView.findViewById(R.id.tb_receipt_details) as TextView
        val paymentDetails = headerView.findViewById(R.id.tb_payment_details) as TextView
        val invoiceDetails = headerView.findViewById(R.id.tb_invoice_details) as TextView
        val summary = headerView.findViewById(R.id.tb_summary) as TextView

        receiptDetails.setTextColor(resources.getColor(R.color.white))
        val drawable = receiptDetails.getBackground() as GradientDrawable
        drawable.setColor(resources.getColor(R.color.received_payments))

        paymentDetails.setTextColor(resources.getColor(R.color.main))
        val drawablepaymentDetails = paymentDetails.getBackground() as GradientDrawable
        drawablepaymentDetails.setColor(resources.getColor(R.color.white))

        invoiceDetails.setTextColor(resources.getColor(R.color.main))
        val drawableinvoiceDetails = invoiceDetails.getBackground() as GradientDrawable
        drawableinvoiceDetails.setColor(resources.getColor(R.color.white))

        summary.setTextColor(resources.getColor(R.color.main))
        val summarydrawable = summary.getBackground() as GradientDrawable
        summarydrawable.setColor(resources.getColor(R.color.white))

        tabLayout!!.getTabAt(0)!!.setCustomView(receiptDetails)
        tabLayout!!.getTabAt(1)!!.setCustomView(paymentDetails)
        tabLayout!!.getTabAt(2)!!.setCustomView(invoiceDetails)
        tabLayout!!.getTabAt(3)!!.setCustomView(summary)



        tabLayout!!.addOnTabSelectedListener(object : TabLayout.OnTabSelectedListener {

            override fun onTabSelected(tab: TabLayout.Tab?) {

                if(tab!!.position==0)
                {
                    Log.e("tab","0")

                    receiptDetails.setTextColor(resources.getColor(R.color.white))
                    val drawable = receiptDetails.getBackground() as GradientDrawable
                    drawable.setColor(resources.getColor(R.color.received_payments))

                    paymentDetails.setTextColor(resources.getColor(R.color.main))
                    val drawablepaymentDetails = paymentDetails.getBackground() as GradientDrawable
                    drawablepaymentDetails.setColor(resources.getColor(R.color.white))

                    invoiceDetails.setTextColor(resources.getColor(R.color.main))
                    val drawableinvoiceDetails = invoiceDetails.getBackground() as GradientDrawable
                    drawableinvoiceDetails.setColor(resources.getColor(R.color.white))

                    summary.setTextColor(resources.getColor(R.color.main))
                    val summarydrawable = summary.getBackground() as GradientDrawable
                    summarydrawable.setColor(resources.getColor(R.color.white))
                }
                else if(tab!!.position==1 && myPreference!!.getReceiptStatus())
                {

                    Log.e("tab","1")
                    Log.e("stataus",myPreference!!.getReceiptStatus().toString())

                    paymentDetails.setTextColor(resources.getColor(R.color.white))
                    val drawable = paymentDetails.getBackground() as GradientDrawable
                    drawable.setColor(resources.getColor(R.color.received_payments))

                    receiptDetails.setTextColor(resources.getColor(R.color.main))
                    val drawablereceiptDetails= receiptDetails.getBackground() as GradientDrawable
                    drawablereceiptDetails.setColor(resources.getColor(R.color.white))

                    invoiceDetails.setTextColor(resources.getColor(R.color.main))
                    val drawableinvoiceDetails = invoiceDetails.getBackground() as GradientDrawable
                    drawableinvoiceDetails.setColor(resources.getColor(R.color.white))

                    summary.setTextColor(resources.getColor(R.color.main))
                    val summarydrawable = summary.getBackground() as GradientDrawable
                    summarydrawable.setColor(resources.getColor(R.color.white))


                }
                else if(tab!!.position==2)
                {
                    Log.e("tab","2")

                    invoiceDetails.setTextColor(resources.getColor(R.color.white))
                    val drawable = invoiceDetails.getBackground() as GradientDrawable
                    drawable.setColor(resources.getColor(R.color.received_payments))

                    receiptDetails.setTextColor(resources.getColor(R.color.main))
                    val drawablereceiptDetails= receiptDetails.getBackground() as GradientDrawable
                    drawablereceiptDetails.setColor(resources.getColor(R.color.white))

                    paymentDetails.setTextColor(resources.getColor(R.color.main))
                    val drawablepaymentDetails = paymentDetails.getBackground() as GradientDrawable
                    drawablepaymentDetails.setColor(resources.getColor(R.color.white))

                    summary.setTextColor(resources.getColor(R.color.main))
                    val summarydrawable = summary.getBackground() as GradientDrawable
                    summarydrawable.setColor(resources.getColor(R.color.white))


                }
                else if(tab!!.position==3)
                {
                    Log.e("tab","3")

                    summary.setTextColor(resources.getColor(R.color.white))
                    val drawable = summary.getBackground() as GradientDrawable
                    drawable.setColor(resources.getColor(R.color.received_payments))

                    receiptDetails.setTextColor(resources.getColor(R.color.main))
                    val drawablereceiptDetails = receiptDetails.getBackground() as GradientDrawable
                    drawablereceiptDetails.setColor(resources.getColor(R.color.white))

                    paymentDetails.setTextColor(resources.getColor(R.color.main))
                    val drawablepaymentDetails = paymentDetails.getBackground() as GradientDrawable
                    drawablepaymentDetails.setColor(resources.getColor(R.color.white))

                    invoiceDetails.setTextColor(resources.getColor(R.color.main))
                    val drawableinvoiceDetails = invoiceDetails.getBackground() as GradientDrawable
                    drawableinvoiceDetails.setColor(resources.getColor(R.color.white))
                }
                else {

                }

            }
            override fun onTabUnselected(tab:TabLayout.Tab?){
            }
            override fun onTabReselected(tab:TabLayout.Tab?) {
            }
        })


    }

    private fun setupViewPager(viewPager: ViewPager) {
        viewPager.setOffscreenPageLimit(-1);
        val adapter = ViewPagerAdapter(supportFragmentManager)
        viewPager.adapter = adapter



    }

   inner class ViewPagerAdapter(manager: FragmentManager) : FragmentPagerAdapter(manager) {



        override fun getItem(position: Int): Fragment? {
            var fragment: Fragment? = null

            if (position == 0 ) {
                Log.e("frag",position.toString())
                fragment = ReceiptDetailsFragment()
            } else if (position == 1 && myPreference!!.getReceiptStatus() ) {
                Log.e("frag",position.toString())
                fragment = PaymentDetailsFragment()
            } else if (position == 2) {
                Log.e("frag",position.toString())
                fragment = InvoiceDetailsFragment()
            } else if (position == 3) {
                Log.e("frag",position.toString())
                fragment = InvoiceDetailsFragment()
            }
            return fragment
        }

        override fun getPageTitle(position: Int): CharSequence {
            return when (position) {
                0 -> "Receipt Details"
                1 -> "Payment Details"
                2 -> "Invocie Details"
                3 -> "Summary"
                else -> throw IllegalArgumentException()
            }
        }

        override fun getCount(): Int {
            return 4
        }
    }

    override fun onFragmentInteraction(jsonObject: JSONObject) {
        //session intialization
        val myPreference = Session(this)
        myPreference.setJsonObject(jsonObject.toString())
        viewPager!!.setCurrentItem(1,true)


    }


    override fun onFragmentInteraction(uri: Uri) {

    }

}

private operator fun Int.invoke(i: Int) {

}
  

我上面已经安装了NewPaymentActivity类，但是问题是我运行此代码后遇到了一个空指针异常，我需要在内部类中使用会话值，但是会话初始化似乎传递了空值。   在内部类内部，我使用了 myPreference !!。getReceiptStatus（），但myPreference的值为null。下面我还将记录我的日志记录。

 Process: com.salesrep.auxxa.alliontechnologies.auxxasr, PID: 6082
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Class java.lang.Object.getClass()' on a null object reference

1 个答案:

答案 0 :(得分：1)

myPreference!!.getReceiptStatus()

避免使用“ !!”，请务必检查是否可以为空，

myPreference?.let { it.getReceiptStatus() }

像这样使用，异常将得到解决

override fun onFragmentInteraction(jsonObject: JSONObject) {
    //session intialization
    val myPreference = Session(this)
    myPreference.setJsonObject(jsonObject.toString())
    viewPager!!.setCurrentItem(1,true)


}

在这里您要分配myPreference的局部变量，我认为您可能需要更改或将其分配给全局变量 只需从-val myPreference = Session（this）中删除val

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