小编Smi*_*fat的帖子

这是我的简单 xml 文件

<?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"
android:gravity="center"
android:orientation="vertical"
tools:context=".MainActivity">
<FrameLayout
    android:id="@+id/main_screen"
    android:layout_width="match_parent"
    android:layout_height="593dp"
    android:background="@color/CadetBlue"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.0">
</FrameLayout>
<android.support.design.widget.BottomNavigationView
    android:id="@+id/bottom_menu"
    style="@style/Widget.MaterialComponents.BottomNavigationView.Colored"
    android:layout_width="match_parent"
    android:layout_height="67dp"
    android:layout_alignParentBottom="true"
    android:baselineAligned="false"
    app:itemBackground="@color/colorPrimary1"
    app:itemIconTint="@drawable/item_selector"
    app:itemTextColor="@drawable/item_selector"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/main_screen"
    app:menu="@menu/nav_items" />

我的 build.gradle 文件是

    //noinspection GradleCompatible
   apply plugin: 'com.android.application'

   android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.smile_sifat.donatethefloody"
        minSdkVersion 26
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner 
       "android.support.test.runner.AndroidJUnitRunner"
       }
       buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 
     'proguard-rules.pro'
        }
    } …