Question

任何人都可以帮我找到这段代码中的错误，因为它说，它不能在主要活动中膨胀片段，顺便说一句，我是android的新手。我试图将膨胀的代码行更改为onCreate函数中的最后一行，但它什么也没做。

以下是活动代码：

 package com.voicenoteinc.tictactou

import android.graphics.Color
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.support.v4.app.FragmentActivity
import android.support.v4.app.Fragment
import android.view.View
import android.widget.Button
import kotlinx.android.synthetic.main.fragment_test.*

class MainActivity : AppCompatActivity() {
    var tstFragment:TestFragment? = null
    val manager = supportFragmentManager
    val FRAGMENT_TAG = "fragment_tag"
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        if (manager.findFragmentByTag(FRAGMENT_TAG) != null) {
            tstFragment = manager.findFragmentByTag(FRAGMENT_TAG) as TestFragment
        }
        if (tstFragment == null) {
            tstFragment = TestFragment()
            manager.beginTransaction().add(tstFragment, FRAGMENT_TAG).commit()
        }

    }
}

XML活动：

<?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:gravity="center"
    tools:context="com.voicenoteinc.tictactou.MainActivity">

    <fragment
        android:id="@+id/fragment"
        android:name="com.voicenoteinc.tictactou.TestFragment"
        android:tag="fragment_tag"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        tools:layout="@layout/fragment_test" />
</LinearLayout>

片段类：

package com.voicenoteinc.tictactou

import android.content.Context
import android.graphics.Color
import android.net.Uri
import android.os.Bundle
import android.support.v4.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import kotlinx.android.synthetic.main.fragment_test.*

class TestFragment : Fragment() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
       retainInstance = true
    }

    override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        bu.setOnClickListener { bu.setBackgroundColor(Color.CYAN) }
        return inflater!!.inflate(R.layout.fragment_test, container, false)
    }
}// Required empty public constructor

Answer 1

有两种方法可以将Fragment添加到Activity。

像在此处一样静态添加：

<fragment
    android:id="@+id/fragment"
    android:name="com.voicenoteinc.tictactou.TestFragment"
    android:tag="fragment_tag"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_weight="1"
    tools:layout="@layout/fragment_test" />

将其动态添加到ViewGroup，如下所示：

ExampleFragment fragment = new ExampleFragment();
fragmentTransaction.add(R.id.fragment_container, fragment);
fragmentTransaction.commit();

看来你试图在这里做两件事。假设你想静态添加它，你可以安全地删除所有这些代码：

// Remove all this code
if (manager.findFragmentByTag(FRAGMENT_TAG) != null) {
    tstFragment = manager.findFragmentByTag(FRAGMENT_TAG) as TestFragment
}
if (tstFragment == null) {
    tstFragment = TestFragment()
    manager.beginTransaction().add(tstFragment, FRAGMENT_TAG).commit()
}

在Adding a fragment to an activity

here

片段错误：XML二进制文件：错误膨胀片段类

1 个答案: