RecyclerView未在NestedScrollView中显示

Question

我在StackOverflow上看了几个类似的事件.但似乎没有一个适用于我的情况.我遇到的问题是我的RecyclerView正在运行,但没有显示任何内容.我已经运行了多个测试来试图弄清楚它为什么不起作用,但所有人都支持它正常工作的事实.

登录getItemCount返回3,这是正确的数字.我只是不明白为什么它没有显示.我回顾了我在之前的活动中所做的回收站视图,它们都匹配到一定程度(其他回收商有更多信息可以设置).

感谢您提供任何帮助.

编辑:我发现了这个问题,但仍然需要帮助.正是崩溃的工具栏导致了它.如果我在NestedScrollView外移动RecyclerView,我可以看到这些项目.但是,内容不能像activity_project_detail.xml中注释掉的TextView那样正确移动.我想我的新问题是如何在NestedScrollView中使用RecyclerView.谢谢!

ProjectDetailsActivity.java

package com.austinerck.projectpanda.activity;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;

import com.austinerck.projectpanda.R;
import com.austinerck.projectpanda.adapter.TaskAdapter;
import com.austinerck.projectpanda.data.LocalDatabase;
import com.austinerck.projectpanda.data.Project;
import com.austinerck.projectpanda.data.Task;

import java.util.ArrayList;

public class ProjectDetailsActivity extends AppCompatActivity {

    private boolean connectionState;

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

        //Sets toolbar and up navigation
        setSupportActionBar((Toolbar) findViewById(R.id.toolbar));
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        //Gets the connection state from the intent
        connectionState = getIntent().getExtras().getBoolean(LocalDatabase.CONNECTION_STATE);

        //Gets the projects from the intent
        Project project = getIntent().getExtras().getParcelable(LocalDatabase.PROJECT_DETAILS);

        //Sets activity title
        setTitle(project.getTitle());

        //Generates Task arrays
        ArrayList<Task> tasksUncompleted = Task.getUncompletedTasks(project.getTasks());
        ArrayList<Task> tasksCompleted = Task.getCompletedTasks(project.getTasks());

        //TODO: Fix recycler views
        RecyclerView recyclerUncompleted = (RecyclerView) findViewById(R.id.detail_uncompleted);
        recyclerUncompleted.setLayoutManager(new LinearLayoutManager(this));
        recyclerUncompleted.setAdapter(new TaskAdapter(tasksUncompleted));
        registerForContextMenu(recyclerUncompleted);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_projects_list, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

TaskAdapter.java

package com.austinerck.projectpanda.adapter;

import android.app.Activity;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.austinerck.projectpanda.R;
import com.austinerck.projectpanda.data.LocalDatabase;
import com.austinerck.projectpanda.data.Project;
import com.austinerck.projectpanda.data.ProjectCardView;
import com.austinerck.projectpanda.data.Task;
import com.austinerck.projectpanda.data.TaskView;

import java.util.ArrayList;

public class TaskAdapter extends RecyclerView.Adapter {

    private ArrayList<Task> tasks;

    public TaskAdapter(ArrayList<Task> tasks) {
        this.tasks = tasks;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        //Selects the layout used in the Recycler
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fragment_task, parent, false);

        return new TaskView(view);
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

        TaskView view = (TaskView) holder;

        //Gets the views that need to be changed
        view.getTitle().setText(tasks.get(position).getTitle());
        view.getSubtitle().setText(tasks.get(position).getSubtitle());
        view.getCheckbox().setChecked(tasks.get(position).isCompleted());

    }

    @Override
    public int getItemCount() {

        Log.e(LocalDatabase.LOG_TAG, "GetItemCount: " + tasks.size());
        return tasks.size();
    }
}

TaskView.java

package com.austinerck.projectpanda.data;

import android.app.Activity;
import android.content.Intent;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.CheckBox;
import android.widget.TextView;

import com.austinerck.projectpanda.R;
import com.austinerck.projectpanda.activity.ProjectDetailsActivity;
import com.austinerck.projectpanda.activity.ProjectsListActivity;
import com.austinerck.projectpanda.activity.WelcomeActivity;

public class TaskView extends RecyclerView.ViewHolder {

    private View view;
    private TextView title, subtitle;
    private CheckBox checkbox;

    public TaskView(View view) {
        super(view);

        //Gets the different parts of a layout
        this.view = view;
        this.title = (TextView) view.findViewById(R.id.task_title);
        this.subtitle = (TextView) view.findViewById(R.id.task_subtitle);
        this.checkbox = (CheckBox) view.findViewById(R.id.task_checkbox);
    }

    public View getView() {
        return view;
    }

    public TextView getTitle() {
        return title;
    }

    public TextView getSubtitle() {
        return subtitle;
    }

    public CheckBox getCheckbox() {
        return checkbox;
    }
}

activity_project_details.xml

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="192dp"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    android:fitsSystemWindows="true">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/toolbar_collapsing"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_scrollFlags="scroll|exitUntilCollapsed"
        android:fitsSystemWindows="true"
        app:contentScrim="?attr/colorPrimary"
        app:expandedTitleMarginStart="48dp"
        app:expandedTitleMarginEnd="64dp">

        <ImageView
            android:id="@+id/detail_background"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scaleType="centerCrop"
            android:fitsSystemWindows="true"
            app:layout_collapseMode="parallax"/>

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:layout_collapseMode="pin"/>

    </android.support.design.widget.CollapsingToolbarLayout>

</android.support.design.widget.AppBarLayout>

<android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="fill_vertical"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <!--<TextView
            android:layout_width="match_parent"
            android:layout_height="@dimen/detail_header_height"
            android:paddingLeft="@dimen/spacing_m"
            android:gravity="center_vertical"
            android:text="@string/details_uncomp"
            android:textSize="@dimen/text_body"
            android:textColor="@color/text_subheader"/>-->

        <android.support.v7.widget.RecyclerView
            android:id="@+id/detail_uncompleted"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>

        <!--<TextView
            android:layout_width="match_parent"
            android:layout_height="@dimen/detail_header_height"
            android:paddingLeft="@dimen/spacing_m"
            android:gravity="center_vertical"
            android:text="@string/details_comp"
            android:textSize="@dimen/text_body"
            android:textColor="@color/text_subheader"/>-->

    </LinearLayout>

</android.support.v4.widget.NestedScrollView>

fragment_task.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="@dimen/spacing_xxl"
    android:paddingLeft="@dimen/spacing_m"
    android:paddingRight="@dimen/spacing_m"
    android:gravity="center_vertical">

    <CheckBox
        android:id="@+id/task_checkbox"
        android:layout_width="@dimen/spacing_l"
        android:layout_height="@dimen/spacing_l" />

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingLeft="@dimen/spacing_xl">

        <TextView
            android:id="@+id/task_title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Set Austin on fire"
            android:textSize="@dimen/text_subheading"
            android:textColor="@color/text"/>

        <TextView
            android:id="@+id/task_subtitle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Light Austin on fire using a Zippo"
            android:textSize="@dimen/text_body"
            android:textColor="@color/text_subheader"/>

    </LinearLayout>

</LinearLayout>

Answer 1

将此属性添加到NestedScrollView:

android:fillViewport="true"

Answer 2

首先，将fillViewport属性添加到您的NestedScrollView：

<android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="fill_vertical"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    android:fillViewport="true">

另外，你必须在RecyclerView的LayoutManager中使用setAutoMesureEnabled方法：

LinearLayoutManager linearLayoutManager = new LinearLayoutManager( getActivity() );                     
linearLayoutManager.setOrientation( LinearLayoutManager.VERTICAL );
linearLayoutManager.setAutoMeasureEnabled( true );

该setAutoMeasureEnabled方法是可用的，因为在支持设计库23.2。