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java - 如何获取要更新的 Android 微调器文本？

问题描述

我的活动中有一个微调器。

微调器

顶部微调栏用作标题，然后在其下方有一个导航栏，在下半部分有一个片段容器。

微调器包含它通过的所有练习的列表。

在此处输入图像描述

单击微调器下拉列表中的一项后，我希望更新微调器文本，但是没有发生任何更改...

我收到以下消息：

W/e.exerciseappv: Accessing hidden field Landroid/widget/AbsListView;->mIsChildViewEnabled:Z (greylist, reflection, allowed)

D/OpenGLRenderer: endAllActiveAnimators on 0xc6707410 (DropDownListView) with handle 0xc6e4a5f0

我怎样才能让我的基本微调器工作（或者有人有解决方法）？

活动



import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.ViewModelProviders;
import com.example.exerciseappv5.Fragments.ExerciseGraphFragment;
import com.example.exerciseappv5.Fragments.RecordExerciseFragment;
import com.example.exerciseappv5.Fragments.RecordExerciseHistoryFragment;
import com.example.exerciseappv5.ViewModels.ChildExerciseViewModel;
import com.google.android.material.bottomnavigation.BottomNavigationView;

import java.util.ArrayList;
import java.util.List;

public class RecordExerciseActivity2 extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    List<String> allChildExerciseNames = new ArrayList<>();
    public static final String PARENT_EXERCISE_ID = "-999";
    public static final String EXTRA_DATE = "com.example.exerciseappv4.EXTRA_DATE";
    public static final String EXTRA_WEEK_DATES = "1";
    public static String EXTRA_JUNCTIONID = "EXERCISE_JUNCTION_ID";
    int parentExerciseID;
    private ChildExerciseViewModel childExerciseViewModel;
    String firstExerciseName;
    String selectedExercise;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_record_exercise);

        getSupportActionBar().hide();

        Intent intent = getIntent();
        if (intent.hasExtra(PARENT_EXERCISE_ID)) {
            parentExerciseID = Integer.parseInt(intent.getStringExtra(PARENT_EXERCISE_ID));
        }

        BottomNavigationView bottomNav = findViewById(R.id.top_navigation);
        bottomNav.setOnNavigationItemSelectedListener(navListener);

        getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container2, new RecordExerciseFragment()).commit();

        //getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_back);
        childExerciseViewModel = ViewModelProviders.of(this).get(ChildExerciseViewModel.class);
        childExerciseViewModel.getChildExerciseNameFromParentID(parentExerciseID).observe(this, this::setChildExerciseName);
        childExerciseViewModel.getAllchildExercisesFromParentID(parentExerciseID).observe(this, this::getAllChildExercisesFromParentID);


        Spinner spinner =  findViewById(R.id.spinner1);
        ArrayList<String> spinnerStringArray = new ArrayList<>();
        //Add your data to your array
        spinnerStringArray.addAll(allChildExerciseNames);
        ArrayAdapter<String> spinnerAdapter = new ArrayAdapter<String>(this,
               android.R.layout.simple_spinner_dropdown_item, allChildExerciseNames);
        spinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(spinnerAdapter);
        spinner.setOnItemSelectedListener(this);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        selectedExercise = parent.getItemAtPosition(position).toString();
        Toast.makeText(parent.getContext(), selectedExercise, Toast.LENGTH_SHORT).show();
        Log.i("spinner item clicked ", selectedExercise);
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }

    private BottomNavigationView.OnNavigationItemSelectedListener navListener =
            new BottomNavigationView.OnNavigationItemSelectedListener() {
                @Override
                public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                    Fragment selectedFragment = null;

                    switch (item.getItemId()) {
                        case R.id.nav_track:
                            selectedFragment = new RecordExerciseFragment();
                            break;
                        case R.id.nav_history:
                            selectedFragment = new RecordExerciseHistoryFragment();
                            break;
                        case R.id.nav_exercise_list:
                            selectedFragment = new ExerciseGraphFragment();
                            break;
                    }
                    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container2, selectedFragment).commit();
                    return true;
                }
            };

    private void setChildExerciseName(String childExerciseName) {
        firstExerciseName = childExerciseName;
    }

    public String getSelectedExercise() {
        return selectedExercise;
    }

    private void getAllChildExercisesFromParentID(List<String> allChildExercisesReceived) {
        allChildExerciseNames.addAll(allChildExercisesReceived);
    }
}

活动布局 XML

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <View style="@style/Full_Divider"
        android:id="@+id/divider9"
        android:layout_width="wrap_content"
        android:layout_height="1dp"
        android:layout_below="@+id/spinner1"/>

    <View style="@style/Full_Divider"
        android:id="@+id/divider10"
        android:layout_width="wrap_content"
        android:layout_height="1dp"
        android:layout_below="@+id/top_navigation" />


    <FrameLayout
        android:id="@+id/fragment_container2"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/divider10" />

    <androidx.appcompat.widget.AppCompatSpinner
        android:id="@+id/spinner1"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"

        android:layout_marginEnd="1dp"
        android:layout_marginRight="1dp"
        android:gravity="right"
        android:padding="8dp" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/top_navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/spinner1"
        app:itemTextColor="#ffffff"
        app:itemIconTint="#ffffff"
        app:menu="@menu/top_navigation"
        android:background="#292929" />

</RelativeLayout>

构建.Gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.3"

    defaultConfig {
        applicationId "com.example.exerciseappv5"
        minSdkVersion 16
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility = 1.8
        targetCompatibility = 1.8

        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {

    implementation 'com.github.barteksc:android-pdf-viewer:2.8.2'

    def lifecycle_version = "1.1.1"
    def room_version = "1.1.1"

    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'com.google.android.material:material:1.1.0-rc01'
    implementation 'androidx.cardview:cardview:1.0.0'




    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

    implementation 'androidx.recyclerview:recyclerview:1.0.0'
    implementation 'android.arch.lifecycle:extensions:1.0.0-alpha1'
    annotationProcessor 'android.arch.lifecycle:compiler:1.1.1'

    implementation 'android.arch.persistence.room:runtime:1.0.0-alpha1'
    annotationProcessor 'android.arch.persistence.room:compiler:1.0.0-alpha1'
}

标签： javaandroidxmlandroid-layoutandroid-spinner

解决方案

Spinner目前您正在为in进行整个设置onCreate()：您使用（可能为空的）数据列表实例化适配器并调用spinner.setAdapter(spinnerAdapter);

之后您只需更改数据列表：每次getAllChildExercisesFromParentID(List<String>)调用时，您都会将几个Strings 添加到您传递给适配器的数据列表中。但是你永远不会调用notifyDatasetChanged()适配器，我认为这就是事情开始出错的地方。

运行时不会抛出一个（如果我没记错的话Exception，就会出现这种情况）——你只会看到一个带有非空下拉列表的空（！），并且ListView选择一个项目没有任何效果。SpinnerSpinner

因此，要解决您的问题，您可以在调用Spinner时重新创建一个新适配器。getAllChildExercisesFromParentID(List<String>)在这种情况下，您需要创建您的Spinnera 字段Activity，以便可以从此方法访问它：

private Spinner spinner;

初始化它onCreate()但不要设置适配器：

spinner =  findViewById(R.id.spinner1);
spinner.setOnItemSelectedListener(this);

Spinner在收到数据时创建适配器的新实例：

private void getAllChildExercisesFromParentID(List<String> allChildExercisesReceived){
    // maybe removing old data is a good idea?
    allChildExerciseNames.clear();

    allChildExerciseNames.addAll(allChildExercisesReceived);
 
    ArrayAdapter<String> spinnerAdapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_spinner_dropdown_item, allChildExerciseNames);
    spinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(spinnerAdapter);

}

或者你让你Activity有一个领域private ArrayAdapter<String> spinnerAdapter;

完全初始化Spinnerin onCreate()：

Spinner spinner =  findViewById(R.id.spinner1);
spinnerAdapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_spinner_dropdown_item, allChildExerciseNames);
    spinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(spinnerAdapter);

spinner.setOnItemSelectedListener(this);

...并在收到数据时更新数据列表（以及随之而来的适配器）：

private void getAllChildExercisesFromParentID(List<String> allChildExercisesReceived){
    // remove old data 
    allChildExerciseNames.clear();

    allChildExerciseNames.addAll(allChildExercisesReceived);
    spinnerAdapter.notifyDataSetChanged();
}

我更喜欢第二个版本，因为它不需要每次刷新数据时都创建一个新对象——它可以帮助提高性能（但在这种情况下，对现代设备的影响几乎不会被注意到，所以更多的是代码风格）

顺便说一句，您当然可以并且应该将其保留Spinner在您的布局中 - 这AppCompatSpinner只是我试图摆脱奇怪的“Landroid/widget/AbsListView ...”消息，该消息恰好与Spinner问题同时弹出。

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