如何用android studio中的新片段替换已打开的片段?
我试图用PickPowerFragment片段替换MainFragment片段,但当我按下MainFragment中的按钮以PickPowerFragment替换MainFragment时,应用程序崩溃。 我能够按照教程中给出的那样成功地在java中加载PickPowerFragment,但是当我在Kotlin中尝试加载时,应用程序崩溃了(只是为了练习)。 那么如何使用Kotlin语法替换片段呢 活动\u hero\u me.xml如何用android studio中的新片段替换已打开的片段?,android,android-fragments,kotlin,Android,Android Fragments,Kotlin,我试图用PickPowerFragment片段替换MainFragment片段,但当我按下MainFragment中的按钮以PickPowerFragment替换MainFragment时,应用程序崩溃。 我能够按照教程中给出的那样成功地在java中加载PickPowerFragment,但是当我在Kotlin中尝试加载时,应用程序崩溃了(只是为了练习)。 那么如何使用Kotlin语法替换片段呢 活动\u hero\u me.xml <?xml version="1.0" encoding
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.mandar.herome.Activities.HeroMe"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="25dp">
<FrameLayout
android:id="@+id/ReplaceFrame"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0">
</FrameLayout>
</android.support.constraint.ConstraintLayout>
这里我从MainFragment调用函数loadPickPowerScreen()
我测试了按钮(我用来用pickPowerFragment替换MainFragment的按钮)是否正常工作,方法是在单击按钮时使用它修改按钮上的文本,它似乎工作得很好。所以我猜MainFragment.kt应该没有任何问题
package com.example.mandar.herome.Fragments
import android.app.Fragment
import android.content.Context
import android.net.Uri
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.example.mandar.herome.R
/**
* A simple [Fragment] subclass.
* Activities that contain this fragment must implement the
* [PickPowerFragment.OnFragmentInteractionListener] interface
* to handle interaction events.
* Use the [PickPowerFragment.newInstance] factory method to
* create an instance of this fragment.
*/
class PickPowerFragment : Fragment() {
// TODO: Rename and change types of parameters
private var mParam1: String? = null
private var mParam2: String? = null
private var mListener: pickPowerInteractionListener? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
if (arguments != null) {
mParam1 = arguments.getString(ARG_PARAM1)
mParam2 = arguments.getString(ARG_PARAM2)
}
}
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
val view = inflater!!.inflate(R.layout.fragment_pick_power, container, false)
// Inflate the layout for this fragment
return view
}
// TODO: Rename method, update argument and hook method into UI event
fun onButtonPressed(uri: Uri) {
if (mListener != null) {
mListener!!.onPickPowerInteraction(uri)
}
}
override fun onAttach(context: Context?) {
super.onAttach(context)
if (context is pickPowerInteractionListener) {
mListener = context
} else {
throw RuntimeException(context!!.toString() + " must implement OnFragmentInteractionListener")
}
}
override fun onDetach() {
super.onDetach()
mListener = null
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
*
*
* See the Android Training lesson [Communicating with Other Fragments](http://developer.android.com/training/basics/fragments/communicating.html) for more information.
*/
interface pickPowerInteractionListener {
// TODO: Update argument type and name
fun onPickPowerInteraction(uri: Uri)
}
companion object {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private val ARG_PARAM1 = "param1"
private val ARG_PARAM2 = "param2"
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment PickPowerFragment.
*/
// TODO: Rename and change types and number of parameters
fun newInstance(param1: String, param2: String): PickPowerFragment {
val fragment = PickPowerFragment()
val args = Bundle()
args.putString(ARG_PARAM1, param1)
args.putString(ARG_PARAM2, param2)
fragment.arguments = args
return fragment
}
}
}// Required empty public constructor
下面是MainFragment.kt中的onClick()方法
var onClick = View.OnClickListener(){view ->
var heroActivity : HeroMe = HeroMe()
heroActivity.loadPickPowerScreen()
}
这里是fragment PickPowerFragment.kt
package com.example.mandar.herome.Fragments
import android.app.Fragment
import android.content.Context
import android.net.Uri
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.example.mandar.herome.R
/**
* A simple [Fragment] subclass.
* Activities that contain this fragment must implement the
* [PickPowerFragment.OnFragmentInteractionListener] interface
* to handle interaction events.
* Use the [PickPowerFragment.newInstance] factory method to
* create an instance of this fragment.
*/
class PickPowerFragment : Fragment() {
// TODO: Rename and change types of parameters
private var mParam1: String? = null
private var mParam2: String? = null
private var mListener: pickPowerInteractionListener? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
if (arguments != null) {
mParam1 = arguments.getString(ARG_PARAM1)
mParam2 = arguments.getString(ARG_PARAM2)
}
}
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
val view = inflater!!.inflate(R.layout.fragment_pick_power, container, false)
// Inflate the layout for this fragment
return view
}
// TODO: Rename method, update argument and hook method into UI event
fun onButtonPressed(uri: Uri) {
if (mListener != null) {
mListener!!.onPickPowerInteraction(uri)
}
}
override fun onAttach(context: Context?) {
super.onAttach(context)
if (context is pickPowerInteractionListener) {
mListener = context
} else {
throw RuntimeException(context!!.toString() + " must implement OnFragmentInteractionListener")
}
}
override fun onDetach() {
super.onDetach()
mListener = null
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
*
*
* See the Android Training lesson [Communicating with Other Fragments](http://developer.android.com/training/basics/fragments/communicating.html) for more information.
*/
interface pickPowerInteractionListener {
// TODO: Update argument type and name
fun onPickPowerInteraction(uri: Uri)
}
companion object {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private val ARG_PARAM1 = "param1"
private val ARG_PARAM2 = "param2"
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment PickPowerFragment.
*/
// TODO: Rename and change types and number of parameters
fun newInstance(param1: String, param2: String): PickPowerFragment {
val fragment = PickPowerFragment()
val args = Bundle()
args.putString(ARG_PARAM1, param1)
args.putString(ARG_PARAM2, param2)
fragment.arguments = args
return fragment
}
}
}// Required empty public constructor
坠机后的logcat:
崩溃前调试器提供的信息:
在这里,我为项目添加Git存储库链接
您不能像这样实例化活动并调用类方法。。。(这在java中是行不通的) var heroActivity:HeroMe=HeroMe()
heroActivity.loadPickPowerScreen()文件 首先将方法
loadPickPowerScreen()
添加到MainFragment.OnMainFragmentInteractionListener
中,然后只需调用var onClick=View.OnClickListener(){View->
mListener.loadPickPowerScreen()
}
我假设
MainFragment
与PickPowerFragment
在onAttach
和onDetach
是您要找的,请尝试遵循一些编码准则:)
编辑
在HeroMe
活动中,您有:
override fun onMainFragmentInteraction(uri: Uri) {
var pickpowerfrag = PickPowerFragment()
fragmentManager.beginTransaction()
.replace(R.id.ReplaceFrame, pickpowerfrag)
.addToBackStack(null)
.commit()
}
然后在OnClickListener
var onClick = View.OnClickListener(){view ->
mListener?.onMainFragmentInteraction(someUri)
}
经过两天的挖掘,我终于找到了解决问题的办法。 在将Java转换为Kotlin时,我在onClick方法中只犯了一个导致崩溃的错误 而不是:
var onClick = View.OnClickListener(){view ->
var heroActivity : HeroMe = HeroMe()
heroActivity.loadPickPowerScreen()
}
守则应该是:
var onClick = View.OnClickListener(){view ->
var heroActivity : HeroMe= activity as HeroMe
heroActivity.loadPickPowerScreen()
}
谢谢所有帮助我的人
解释此代码的工作原理: 当你写作时 var heroActivity:HeroMe=HeroMe() 由于构造函数的存在,它实际上创建了其他对象(活动),而这些对象(活动)与实际加载的活动不同。因此,创建了这个新活动,但没有显示,因为没有调用startActivity方法。所以 heroActivity.loadPickPowerScreen()文件 对未启动的活动调用此方法 现在,这条线 var heroActivity:HeroMe=作为HeroMe的活动 类似于 getActivity() 表单java,返回片段的父活动。 返回类型是Activity,因此我们需要对其进行装箱,以便可以调用该Activity中的函数。
fun replaceFragment(fragment:fragment){
fun replaceFragment(fragment: Fragment) {
mFragmentStack = Stack()
val transaction = mFragmentManager?.beginTransaction()
transaction?.replace(R.id.layout_frame_content, fragment)
(mFragmentStack as Stack<Fragment>).push(fragment)
transaction?.commitAllowingStateLoss()
}
fun addFragment(fragment: Fragment) {
if (mFragmentManager != null) {
val transaction = (mFragmentManager as FragmentManager).beginTransaction()
transaction.add(R.id.layout_frame_content, fragment)
mFragmentStack?.lastElement()?.onPause()
transaction.hide(mFragmentStack?.lastElement())
mFragmentStack?.push(fragment)
transaction.commitAllowingStateLoss()
}
}
MFFragmentStack=堆栈()
val事务=MFFragmentManager?.beginTransaction()
事务处理?.replace(R.id.layout\u frame\u content,fragment)
(MFFragmentStack作为堆栈)。推送(片段)
交易?.commitAllowingStateLoss()
}
乐趣添加片段(片段:片段){
如果(MFFragmentManager!=null){
val事务=(MFFragmentManager作为FragmentManager)。beginTransaction()
事务.添加(R.id.layout\u frame\u content,fragment)
MFFragmentStack?.lastElement()?.onPause()
事务.hide(MFFragmentStack?.lastElement())
MFFragmentStack?推送(碎片)
交易记录.佣金记录状态损失()
}
}
上述方法可用于替换片段并将其添加到自定义片段堆栈和片段管理器中,以添加片段
getSupportFragmentManager().beginTransaction().add(R.id.container,FragmentLogin()).commit();
用于碎片替换
getSupportFragmentManager().beginTransaction().replace(R.id.container,FragmentLogin()).commit()
发布日志猫或异常。@EmanuelS我刚刚上传了日志猫。请检查。谢谢抱歉,但我似乎没有很好地得到解决方案。以下是我所做的:我删除了loadPickPowerScreen()并粘贴到MainFragment.kt MainFragment.OnMainFragmentInteractionListener中。但它开始给我一个错误,说“fragmentManager”是一个未解析的引用。对不起,您能详细说明一下解决方案吗?我只需复制loadPickPowerScreen()中的所有内容并将其粘贴到MainFragment的onClick方法中,就可以让它工作。我不知道为什么它不能与loadPickPowerScreen()一起工作。我应该粘贴整个代码吗?我最初没有粘贴它,因为还有其他与问题无关的东西,如其他按钮、ImageView等。是否有其他方式来共享项目?这也是一个更简单的解决方案:)是的,但我想将所有控制内容放在活动中,以保持代码的组织性。如果您希望查看原始项目,那么这里有一个Git存储库链接:。你能帮我找到问题的确切根源吗?我遇到这个问题的原因是,在第一种情况下,我通过调用MainActivity中的函数来做同样的事情,而现在我只是将代码从函数复制到调用函数的位置。这有区别吗?当我尝试输入“activity.onMainFragmentInteraction(someUri)”时。我给出了onMainFragmentInteraction的错误。我还尝试在loadPickPowerScreen()中输入onMainFragmentInteraction(someUri),这里没有显示错误,但应用程序崩溃。请解释答案,因为您的解决方案对我有效,但与difference@AnnsRahim很抱歉回答不清楚,我补充了澄清。请检查一下。