运行程序后首页不会加载，点击之后才会加载，请问这种情况怎么解决？

努力让自己变得更优秀 2019-05-11 09:33:09
如图 ，不会发gif，只能发静态图片了 ，大概就是这个意思：运行程序后不进行任何操作的时候，无法显示数据，点击屏幕之后才显示。
https://blog.csdn.net/weixin_43889378/article/details/90105812
部分代码：
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:app="http://schemas.android.com/apk/res-auto"

    android:id="@+id/container"

    android:orientation="vertical"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    >



    <FrameLayout

        android:id="@+id/main_view"

        android:layout_width="match_parent"

        android:layout_height="match_parent"

        android:layout_above="@id/nav_view"

        android:orientation="vertical">

    </FrameLayout>

    

    <android.support.design.widget.BottomNavigationView

        android:id="@+id/nav_view"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_alignParentBottom="true"

        app:menu="@menu/bottom_nav_menu"

        app:labelVisibilityMode="labeled"

        >

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



</RelativeLayout>


MainActivity.java

package com.hjl.topview2;



import android.os.Bundle;

import android.support.annotation.NonNull;

import android.support.design.widget.BottomNavigationView;

import android.support.v4.app.Fragment;

import android.support.v4.app.FragmentTransaction;

import android.support.v7.app.AppCompatActivity;

import android.view.MenuItem;



import com.hjl.topview2.view.HomeFragment;

import com.hjl.topview2.view.MineFragment;

import com.hjl.topview2.view.ProjectFragment;

import com.hjl.topview2.view.SystemFragment;



public class MainActivity extends AppCompatActivity {



    private BottomNavigationView bottomNavigationView;

    private HomeFragment homeFragment;

    private SystemFragment systemFragment;

    private ProjectFragment projectFragment;

    private MineFragment mineFragment;

    private Fragment[] fragments;

    private int lastFragment;



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        initFragment();

    }



    private void initFragment() {

        homeFragment = new HomeFragment();

        systemFragment = new SystemFragment();

        projectFragment = new ProjectFragment();

        mineFragment = new MineFragment();

        fragments = new Fragment[]{homeFragment, systemFragment, projectFragment, mineFragment};

        lastFragment = 0;

        //获取Fragment管理器 -> 产生FragmentTransaction对象 ->

        getSupportFragmentManager().beginTransaction().replace(R.id.main_view, homeFragment).show(homeFragment).commit();

        bottomNavigationView = findViewById(R.id.nav_view);

        bottomNavigationView.setOnNavigationItemSelectedListener(changeFragment);

    }



    private BottomNavigationView.OnNavigationItemSelectedListener changeFragment = new BottomNavigationView.OnNavigationItemSelectedListener() {

        @Override

        public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {

            switch (menuItem.getItemId()) {

                case R.id.navigation_home:

                {

                    if (lastFragment != 0) {

                        switchFragment(lastFragment, 0);

                        lastFragment = 0;

                    }

                    return true;

                }

                case R.id.navigation_system:

                {

                    if (lastFragment != 1) {

                        switchFragment(lastFragment, 1);

                        lastFragment = 1;

                    }

                    return true;

                }

                case R.id.navigation_project:

                {

                    if (lastFragment != 2) {

                        switchFragment(lastFragment, 2);

                        lastFragment = 2;

                    }

                    return true;

                }

                case R.id.navigation_mine:

                {

                    if (lastFragment != 3) {

                        switchFragment(lastFragment, 3);

                        lastFragment = 3;

                    }

                    return true;

                }

            }

            return false;

        }

    };



    private void switchFragment(int lastFragment, int index) {

        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

        transaction.hide(fragments[lastFragment]);

        if (!fragments[index].isAdded()) {

            transaction.add(R.id.main_view, fragments[index]);

        }

        transaction.show(fragments[index]).commitAllowingStateLoss();

    }

}


fragment_home.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical"

    >



    <android.support.v7.widget.Toolbar

        android:id="@+id/home_toolbar"

        android:layout_width="match_parent"

        android:layout_height="?attr/actionBarSize"

        android:background="@color/colorPrimary"

        android:fitsSystemWindows="true">



        <RelativeLayout

            android:layout_width="match_parent"

            android:layout_height="match_parent"

            android:layout_marginStart="@dimen/margin_norma"

            android:layout_marginEnd="@dimen/margin_norma">



            <TextView

                android:id="@+id/home_textview"

                android:layout_width="wrap_content"

                android:layout_height="wrap_content"

                android:layout_centerInParent="true"

                android:text="@string/title_home"

                android:textColor="@color/colorWhite"

                android:textSize="@dimen/toolbar_title_tx"

                />



            <ImageView

                android:id="@+id/home_search"

                android:layout_width="@dimen/toolbar_iv_width"

                android:layout_height="@dimen/toolbar_iv_height"

                android:layout_alignParentEnd="true"

                android:layout_centerVertical="true"

                android:contentDescription="@string/search"

                android:scaleType="centerCrop"

                android:src="@mipmap/search"

                />

        </RelativeLayout>



    </android.support.v7.widget.Toolbar>



    <com.hjl.topview2.widget.RefreshLayout

        android:id="@+id/home_swipeRefreshLayout"

        android:layout_width="match_parent"

        android:layout_height="match_parent">



        <ListView

            android:id="@+id/home_list_view"

            android:layout_width="match_parent"

            android:layout_height="match_parent"

            android:scrollbars="none"

            android:divider="#dddddd"

            android:dividerHeight="3px"/>

    </com.hjl.topview2.widget.RefreshLayout>





</LinearLayout>


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王能 2019-05-30
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引用 5 楼 weixin_45069105 的回复:
同问，求大神出来解释
https://bbs.csdn.net/topics/392626334 这是他的原贴
weixin_45069105 2019-05-15
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同问，求大神出来解释
努力让自己变得更优秀 2019-05-13
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引用 2 楼 王能 的回复:
代码都不需要看完，你默认进来没有调switchFragment1能显示出啥？
我用您教的解决SystemFragment的方法，解决了这个问题，但是不知道原因在哪
努力让自己变得更优秀 2019-05-13
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引用 2 楼 王能 的回复:
代码都不需要看完，你默认进来没有调switchFragment1能显示出啥？
在MainActivity.java的initFragment()方法中：
getSupportFragmentManager().beginTransaction().replace(R.id.main_view, homeFragment).show(homeFragment).commit();

不就相当于调了swithcFragment了吗？
王能 2019-05-13
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代码都不需要看完，你默认进来没有调switchFragment1能显示出啥？
努力让自己变得更优秀 2019-05-11
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HomeFragmen.java

package com.hjl.topview2.view;



import android.os.Bundle;

import android.support.v4.app.Fragment;

import android.support.v7.app.AppCompatActivity;

import android.support.v7.widget.Toolbar;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ListView;



import com.hjl.topview2.R;

import com.hjl.topview2.adapter.ArticleAdapter;

import com.hjl.topview2.bean.Article;

import com.hjl.topview2.widget.RefreshLayout;



import org.json.JSONArray;

import org.json.JSONObject;



import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.net.HttpURLConnection;

import java.net.URL;

import java.util.ArrayList;

import java.util.List;



public class HomeFragment extends Fragment {



    private Toolbar toolbar;

    private List<Article> articleList = new ArrayList<>();

    private ArticleAdapter adapter;

    private ListView listView;

    private RefreshLayout refreshLayout;

    private int pageNum = 0;



    @Override

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_home, container, false);

        toolbar = view.findViewById(R.id.home_toolbar);

        refreshLayout = view.findViewById(R.id.home_swipeRefreshLayout);

        listView = view.findViewById(R.id.home_list_view);

        ((AppCompatActivity) getActivity()).setSupportActionBar(toolbar);

        adapter = new ArticleAdapter(articleList);

        listView.setAdapter(adapter);

        initArticle(pageNum);

        // 刷新事件

        refreshLayout.setOnFlushListener(new RefreshLayout.OnFlushListener() {

            @Override

            public void onFlush() {

                articleList.clear();

                pageNum = 0;

                initArticle(pageNum);

                //同步ListView、adapter数据

                adapter.notifyDataSetChanged();

                refreshLayout.setFlushing(false);

            }

        });

        // 加载事件

        refreshLayout.setOnLoadListener(new RefreshLayout.OnLoadListener() {

            @Override

            public void onLoad() {

                pageNum++;

                initArticle(pageNum);

                //同步ListView、adapter数据

                adapter.notifyDataSetChanged();

                refreshLayout.setLoading(false);

            }

        });

        return view;

    }



    @Override

    public void onActivityCreated(Bundle savedInstanceState) {

        super.onActivityCreated(savedInstanceState);

    }



    public void initArticle(final int pageNum) {

            new Thread(new Runnable() {

            @Override

            public void run() {

                HttpURLConnection connection = null;

                BufferedReader reader = null;

                try {

                    String url1 = "https://www.wanandroid.com/article/list/";

                    String url2 = "/json";

                    String string = url1 + (pageNum - 1) +

                            url2;

                    URL url = new URL(string);

                    connection = (HttpURLConnection) url.openConnection();

                    connection.setRequestMethod("GET");

                    connection.setConnectTimeout(8000);

                    connection.setReadTimeout(8000);

                    InputStream in = connection.getInputStream();

                    reader = new BufferedReader(new InputStreamReader(in));

                    StringBuilder response = new StringBuilder();

                    String line;

                    while((line = reader.readLine()) != null) {

                        response.append(line);

                    }

                    parseJSONWithJSONObject(response.toString());

                } catch (Exception e) {

                    e.printStackTrace();

                } finally {

                    if (reader != null) {

                        try {

                            reader.close();

                        } catch (IOException e) {

                            e.printStackTrace();

                        }

                    }

                    if (connection != null) {

                        connection.disconnect();

                    }

                }

            }

        }).start();

    }



    private void parseJSONWithJSONObject(String jsonData) {

        try {

            JSONObject jsonObject = new JSONObject(jsonData);

            JSONObject jsonObject1 = new JSONObject(jsonObject.getJSONObject("data").toString());

            JSONArray jsonArray = new JSONArray(jsonObject1.getJSONArray("datas").toString());

            for (int i = 0; i < jsonArray.length(); i++) {

                JSONObject jsonObject2 = jsonArray.getJSONObject(i);

                Article article = new Article();

                article.setAuthor(jsonObject2.getString("author"));

                article.setChapterId(jsonObject2.getInt("chapterId"));

                article.setChapterName(jsonObject2.getString("chapterName"));

                article.setCollect(jsonObject2.getBoolean("collect"));

                article.setCourseId(jsonObject2.getInt("courseId"));

                article.setFresh(jsonObject2.getBoolean("fresh"));

                article.setId(jsonObject2.getInt("id"));

                article.setLink(jsonObject2.getString("link"));

                article.setNiceDate(jsonObject2.getString("niceDate"));

                article.setSuperChapterId(jsonObject2.getInt("superChapterId"));

                article.setSuperChapterName(jsonObject2.getString("superChapterName"));

//                article.setTags(jsonObject);

                article.setTitle(jsonObject2.getString("title"));

                articleList.add(article);

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }



}
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