Question

该问题所绑定的链接可能是重复的，与我的问题完全无关，因为片段的代码似乎是问题所在...

我正在尝试创建一个包含两个片段和两个按钮的项目，两个按钮在单击时显示片段。我在下面提供我的文件。当我尝试运行该应用程序时，它崩溃并无法运行。我正在用Kotlin进行编码。

Fragment1 Java文件

package example.alyssa.com.a10

import android.content.Context
import android.net.Uri
import android.os.Bundle
import android.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup


private const val ARG_PARAM1 = "param1"
private const val ARG_PARAM2 = "param2"

class Fragment1 : Fragment() {
    // TODO: Rename and change types of parameters
    private var param1: String? = null
    private var param2: String? = null
    private var listener: OnFragmentInteractionListener? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            param1 = it.getString(ARG_PARAM1)
            param2 = it.getString(ARG_PARAM2)
        }
    }

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

        return inflater.inflate(R.layout.fragment_fragment1, container, false)
    }


    fun onButtonPressed(uri: Uri) {
        listener?.onFragmentInteraction(uri)
    }

    override fun onAttach(context: Context) {
        super.onAttach(context)
        if (context is OnFragmentInteractionListener) {
            listener = context
        } else {
            throw RuntimeException(context.toString() + " must implement OnFragmentInteractionListener")
        }
    }

    override fun onDetach() {
        super.onDetach()
        listener = null
    }


    interface OnFragmentInteractionListener {

        fun onFragmentInteraction(uri: Uri)
    }

    companion object {

        @JvmStatic
        fun newInstance(param1: String, param2: String) =
                Fragment1().apply {
                    arguments = Bundle().apply {
                        putString(ARG_PARAM1, param1)
                        putString(ARG_PARAM2, param2)
                    }
                }
    }
}

Fragment2 Java文件

package example.alyssa.com.a10

import android.content.Context
import android.net.Uri
import android.os.Bundle
import android.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup


private const val ARG_PARAM1 = "param1"
private const val ARG_PARAM2 = "param2"


class Fragment2 : Fragment() {
    // TODO: Rename and change types of parameters
    private var param1: String? = null
    private var param2: String? = null
    private var listener: OnFragmentInteractionListener? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            param1 = it.getString(ARG_PARAM1)
            param2 = it.getString(ARG_PARAM2)
        }
    }

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

        return inflater.inflate(R.layout.fragment_fragment2, container, false)
    }


    fun onButtonPressed(uri: Uri) {
        listener?.onFragmentInteraction(uri)
    }

    override fun onAttach(context: Context) {
        super.onAttach(context)
        if (context is OnFragmentInteractionListener) {
            listener = context
        } else {
            throw RuntimeException(context.toString() + " must implement OnFragmentInteractionListener")
        }
    }

    override fun onDetach() {
        super.onDetach()
        listener = null
    }


    interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        fun onFragmentInteraction(uri: Uri)
    }

    companion object {
        /**
         * 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 Fragment2.
         */
        // TODO: Rename and change types and number of parameters
        @JvmStatic
        fun newInstance(param1: String, param2: String) =
                Fragment2().apply {
                    arguments = Bundle().apply {
                        putString(ARG_PARAM1, param1)
                        putString(ARG_PARAM2, param2)
                    }
                }
    }
}

主要活动Java文件

package example.alyssa.com.a10

import android.app.Activity
import android.os.Bundle
import android.support.v4.app.Fragment
import android.support.v4.app.FragmentActivity
import android.support.v4.app.FragmentManager
import android.support.v4.app.FragmentTransaction
import android.view.View


class MainActivity : Activity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }
    fun ChangeFragment(view: View) {
        val fragment:Fragment
        if (view == findViewById(R.id.button))
        {
            fragment = Fragment()
            val fm = fragmentManager
            val ft = fm.beginTransaction()
            var replace = ft.replace(R.id.fragment_place,Fragment1)
            ft.commit()
        }
    }
}

private fun Any.replace(fragment_place: Int, fragment1: Fragment1.Companion) {

}

private fun FragmentTransaction.replace(fragment_place: Int, fragment: Fragment) {

}

activity_main.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:onClick="ChangeFragment"
        android:text="Fragment1" />

    <Button
        android:id="@+id/button2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="ChangeFragment"
        android:text="Fragment2" />
<fragment
    android:name="example.alyssa.com.a10.Fragment1"
    android:id="@+id/fragment_place"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</fragment>

</LinearLayout>

fragment_fragment1.xml文件

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Fragment1">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment"
        tools:background="?android:attr/colorAccent" />

</FrameLayout>

fragment_fragment2.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Fragment2">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#d09fdf"
        android:text="@string/hello_blank_fragment" />

</FrameLayout>

build.gradle（项目文件）

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    ext.kotlin_version = '1.2.71'
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.4'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()


    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

build.gradle（模块文件）

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "example.alyssa.com.a10"
        minSdkVersion 14
        targetSdkVersion 14
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.android.support:support-v4:28.0.0'
}

Answer 1

更改此内容：

import android.content.Context
import android.net.Uri
import android.os.Bundle
import android.app.Fragment  // this line
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup

对此：

import android.content.Context
import android.net.Uri
import android.os.Bundle
import android.support.v4.app.Fragment; // this line in both fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup

Answer 2

似乎您已经为片段事务创建了自己的替换函数。请在有趣的ChangeFragment（view：View）中使用类似这样的内置函数：-

val fragment1 = Fragment1()
supportFragmentManager.beginTransaction().replace(R.id.fragment_place, fragment1,"").addToBackStack(null).commit()

希望您发现它有用。还可以在任何地方使用v4 import生成片段。

import android.support.v4.app.Fragment; //您应该导入它。

尝试向项目添加片段时我的应用程序崩溃

2 个答案: