Question

我不明白为什么Kotlin给我这个错误：夸大类片段的错误这是一个非常简单的片段中的代码

MainActivityFragment

import android.support.v4.app.Fragment
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import kotlinx.android.synthetic.main.fragment_main.*

/**
 * A placeholder fragment containing a simple view.
 */
class MainActivityFragment : Fragment() {

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        text.text = "test2"
        return inflater.inflate(R.layout.fragment_main, container, false)
    }

}

fragment_main.xml

<?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=".MainActivityFragment"
    tools:showIn="@layout/activity_main">

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

我在哪里做错了？

Answer 1

您不能在之前给文本分配片段大小。首先在onCreateView上填充片段，然后在onCreate方法上添加文本

Answer 2

在使用视图之前，需要先使其膨胀。将您的代码移至onViewCreated事件：

class MainActivityFragment : Fragment() {

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        return inflater.inflate(R.layout.fragment_main, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        text.text = "test2"
    }

}

Kotlin错误膨胀类片段

2 个答案: