2.《第一行代码》笔记一

一、开始启程
Log的快捷方式：logd/logt等等

二、探究活动
1.使用Menu
建立menu文件夹，新建一个叫main的菜单文件：

在FirstActivity中重写onCreateOptionsMenu()和onCreateOptionsMenu()方法：

    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main,menu);
        return true;
    }
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.add_item:
                break;
            case R.id.remove_item:
                break;
            default:
        }
        return true;
    }

销毁一个活动：finish();

2、使用Intent在活动之间穿梭
启动另一个活动：

Intent intent = new Intent(FirstActivity.this,SecondActivity.class);
startActivity(intent);

隐式：
在manifest文件中sencondacitvity标签添加如下：

    
    


 Intent intent = new Intent("com.lewanjiang.activitytest.ACTION_START");
startActivity(intent);

同时可添加category。:

int1.addCategory("com.lewanjiang.activitytest.MY_CATEGORY");

添加后不要忘记在manifest文件中声明category。

Intent更多用法：打开网址和拨打电话

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setData(Uri.parse("http://bing.com"));
startActivity(intent);
Intent intent1 = new Intent(Intent.ACTION_DIAL);
intent1.setData(Uri.parse("tel:10088"));
startActivity(intent1);

响应打开网页：在manifest的activity的中：

向下一个活动中传递数据：
方法一：
第一个活动中：

String data = "hello bob";
Intent intent = new Intent(MainActivity.this,SecondActivity.class);
intent.putExtra("tran",data);
startActivity(intent);

第二个活动中：

Intent intent = getIntent();
String data = intent.getStringExtra("tran");

常用写法：
第一个活动中：

SecondActivity.actionStart(FirstActivity.this,"dat1","dat2");

第二个活动中：

public static void actionStart(Context context,String data1,String data2) {
    Intent int1 = new Intent(context,SecondActivity.class);
    int1.putExtra("par1",data1);
    int1.putExtra("par2",data2);
    context.startActivity(int1);
}

返回数据给第一个活动：
第一个活动中：

Intent int1 = new Intent(FirstActivity.this,SecondActivity.class);
startActivityForResult(int1,1);
@Overrid
protected void onActivityResult(int reqCod,int resCod,Intent data){
    switch (reqCod) {
        case 1:
            if (resCod == RESULT_OK) {
                String retDat = data.getStringExtra("tran");
                Log.d("FirstActivity", retDat);
            }
            break;
        default:
    }
}

第二个活动中：

Intent int1 = new Intent();
int1.putExtra("tran","Hello bob again");
setResult(RESULT_OK,int1);

响应返回键时，可将以上代码写在onBackPredded()中。

典型生命周期：onCreate、onStart（前台）、onResume（可见）、onPause、onStop、onDestroy、onRestart

        if (savedInstanceState != null) {
            String test = savedInstanceState.getString("extra_test");
            Log.d(TAG,"[onCteate]restore extra_test:" + test);

    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        Log.d(TAG,"onSaveInstanceState");
        outState.putString("extra_test","haha");
    }

    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        String test = savedInstanceState.getString("extra_test");
        Log.d(TAG,"[onRestoreInstanceState]restore extra_test" + test);
    }

内存不足Activity被杀死时与被销毁时一致
避免Activity被重新创建：设置android:configChanges属性

启动模式：standard/singleTop/singleTask/singleInstance 在manifest文件中修改：android:launchMode="singleTask"

Flags:
常用Flags:FLAG_ACTIVITY_NEW_TASK、FLAG_ACTIVITY_SINGLE_TOP、FLAG_ACTIVITY_CLEAR_TOP、FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS

找到当前活动和退出所有活动：

public class BaseActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
        Log.d("BaseActivity",getClass().getSimpleName());
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        ActivityCollector.removeActivity(this);
    }
}
public class ActivityCollector {
    public static List acts = new ArrayList<>();
    public static void addActivity(Activity act) {
        acts.add(act);
    }
    public static void removeActivity(Activity act) {
        acts.remove(act);
    }
    public static void finishAll() {
        for (Activity act:acts) {
            if (!act.isFinishing()) {
                act.finish();
            }
        }
    }
}

三、UI开发
基本控件与布局
android:gravity、android:textSize、android:textColor、android:textAllCaps、android:layout_gravity、android:hint、android:maxLines
textView属性：
点击；android:clickable="true"

Button:
android:textAllCaps
implement View.OnClickListener
public void onClick(View v){ switch(v.getid()){ case: ...} }

EditText:
android:hint、android:maxLines
String inpTex=editText().getText().toString();

ImageView:
android:src
imaVie.setImageResource(R.drawable.hah);

ProgressBar:
style="?android:attr/progressBarStyleHorizontal"
android:max

if(prBar.getVisibility() == View.GONE)
proBar.setVisibility(View.VISIBLE);
int prooo=proBar.getProgress();
proBar.setProgress(666);

AlertDialog:

AlertDialog.Builder dia = new AlertDialog.Builder(MainActivity.this);
dia.setTitle("TITLE");
dia.setMessage("hahahahaha");
dia.setCancelable(true);
dia.setPositiveButton("OK", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        Log.d("MainActivity","haha");
    }
});
dia.setNegativeButton("Cancle", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        Log.d("MainActivity","heihei");
    }
});
dia.show();

progressdialog已停用

四种基本布局：
LinearLayout

RelativeLayout(推荐使用）:
android:layout_alignParentLeft/layout_alignParentRight/layout_alignParentTop/layout_alignParentBotton/layout_alignParentlayout_centerInParent/layout_above/layout_below/toLeftOf/toRightOf

FrameLayout:

android.support.percent.PercentFrameLayout:
compile 'com.android.support:percent:24.2.2
app:layout_widthPercentapp:layout_heightPercent

自定义布局：

隐藏标题栏：

ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            actionBar.hide();
        }

创建自定义控件：

    

public class TitleLayout extends LinearLayout {
    public TitleLayout(Context context, AttributeSet attrs) {
        super(context,attrs);
        LayoutInflater.from(context).inflate(R.layout.title,this);
       Button titleBack = (Button) findViewById(R.id.title_back);
        Button titleEdit = (Button) findViewById(R.id.title_edit);

        titleBack.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                ((Activity)getContext()).finish();
            }
        });
        titleEdit.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getContext(),"haha",Toast.LENGTH_SHORT).show();
            }
        });
    }
}

ListView简单用法：

private String[] data = {"a","b","c","d","e","f","g"};
ArrayAdapter ada = new ArrayAdapter(
        MainActivity.this,android.R.layout.simple_list_item_1,data);
ListView lisVie = (ListView) findViewById(R.id.list_view);
lisVie.setAdapter(ada);

复杂用法：

public class Fruit {
    private String name;
    private int imageId;

    public Fruit(String name,int imageId) {
        this.name = name;
        this.imageId = imageId;
    }

    public String getName() {
        return name;
    }

    public int getImageId() {
        return imageId;
    }
}

public class FruitAdapter extends ArrayAdapter {
    private int resourceId;

    public FruitAdapter(Context context, int textViewResouceId, List objects) {
        super(context,textViewResouceId,objects);
        resourceId = textViewResouceId;
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        Fruit fruit = getItem(position);
        View view;
        ViewHolder viewHolder;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
            viewHolder.fruitName = (TextView) view.findViewById(R.id.fruit_name);
            view.setTag(viewHolder);
        } else {
            view = convertView;
            viewHolder = (ViewHolder) view.getTag();
        }
        viewHolder.fruitImage.setImageResource(fruit.getImageId());
        viewHolder.fruitName.setText(fruit.getName());
        return view;
    }

    class ViewHolder {
        ImageView fruitImage;
        TextView fruitName;
    }
}

public class MainActivity extends AppCompatActivity {
    private List fruitList = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initFruits();
        FruitAdapter adapter = new FruitAdapter(MainActivity.this,R.layout.fruit_item,fruitList);
        ListView listView = (ListView) findViewById(R.id.list_view);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView parent, View view, int position, long id) {
                Fruit fruit = fruitList.get(position);
                Toast.makeText(MainActivity.this,fruit.getName(),Toast.LENGTH_SHORT).show();
            }
        });
    }

    private void initFruits() {
        for (int i = 0;i < 2;i++) {
            Fruit apple = new Fruit("Apple",R.drawable.ic_launcher_background);
            fruitList.add(apple);
            Fruit banana = new Fruit("Banana",R.drawable.ic_launcher_background);
            fruitList.add(banana);
        }
    }
}

1.概述：
RecyclerView的设计与ListView、GridView类似，也使用了Adapter，不过该Adapter并不是ListView中的Adapter，而是RecyclerView的一个静态内部类。该Adapter有一个泛型参数VH，代表的就是ViewHolder。RecyclerView还封装了一个ViewHolder类型，该类型中有一个itemView字段，代表的就是每一项数据的根视图，需要在构造函数中传递给ViewHolder对象。RecyclerView这么设计相当于将ListView的Adapter进行了再次封装，把getView函数中判断是否含有缓存的代码段封装到RecyclerView内部，使这部分逻辑对用户不可见。用户只需要告诉RecyclerView每项数据是怎么样的以及将数据绑定到每项数据上，分别对应的函数为onCreateViewHolder函数、onBindViewHolder函数，当然还需要通过getItemCount告诉RecyclerView有多少项数据，以往适用于ListView的 Adapter中的getView函数中的逻辑就不需要用户来处理了。
基本用法如下，导入listview项目中的fruit类和fruit_item.xml：

public class FruitAdapter extends RecyclerView.Adapter {
    private List mFruLis;
    static class ViewHolder extends RecyclerView.ViewHolder {
        ImageView fruitImage;
        TextView fruitName;
        public ViewHolder(View vie) {
            super(vie);
            fruitImage = (ImageView) vie.findViewById(R.id.fruit_image);
            fruitName = (TextView) vie.findViewById(R.id.fruit_name);
        }
    }

    public FruitAdapter(List fruLis) {
        mFruLis = fruLis;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup par,int vieTyp) {
        View vie = LayoutInflater.from(par.getContext()).inflate(R.layout.fruit_item,par,false);
        ViewHolder hol = new ViewHolder(vie);
        return hol;
    }

    @Override
    public void onBindViewHolder(ViewHolder hol,int pos) {
        Fruit fru = mFruLis.get(pos);
        hol.fruitImage.setImageResource(fru.getImageId());
        hol.fruitName.setText(fru.getName());
    }

    @Override
    public int getItemCount() {
        return mFruLis.size();
    }
}

    RecyclerView recVie = (RecyclerView) findViewById(R.id.recycler_view);
    LinearLayoutManager layMan = new LinearLayoutManager(this);
    recVie.setLayoutManager(layMan);
    FruitAdapter ada = new FruitAdapter(fruLis);
    recVie.setAdapter(ada);

2.高级用法
RecyclerView的另一大特点就是将布局方式抽象为LayoutManager，默认提供了LinearLayoutManager、GridLayoutManager、StaggeredGridLayoutManager 3种布局，对应为线性布局、网格布局、交错网格布局，如果这些都无法满足你的需求，你还可以定制布局管理器实现特定的布局方式。
RecyclerView通过桥接的方式将布局职责抽离出去，使得RecyclerView变得更灵活。例如，如果用户只需要修改RecyclerView的布局方式，只需要修改LayoutManager即可，而不需要操作复杂的RecyclerView类型。而ListView、GridView正好是相反的，它们只是布局方式不一样，但却是两个类型，它们覆写了基类AbsListView的layoutChildren函数来实现不同的布局。显然，通过组合的形式要好于通过继承，因此，RecyclerView在设计上也要好于AbsListView类族。

除此之外，RecyclerView对于Item View的控制也更为精细，可以通过ItemDecotation为Item View添加装饰，也就是在Item View上进行二次加工；又可以用过ItemAnimator为Item View添加动画。

实现横向滚动：
fruit_item.xml 把布局改为垂直方向
MainActivity添加如下代码：

layMan.setOrientation(LinearLayoutManager.HORIZONTAL);

瀑布流布局：
StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(3,StaggeredGridLayoutManager.VERTICAL);

点击事件：
修改FruitAdapter代碼如下：

    static class ViewHolder extends RecyclerView.ViewHolder {
        View fruitView;
        ImageView fruitImage;
        TextView fruitName;
        public ViewHolder(View vie) {
            super(vie);
            fruitView = vie;
            fruitImage = (ImageView) vie.findViewById(R.id.fruit_image);
            fruitName = (TextView) vie.findViewById(R.id.fruit_name);
        }
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup par,int vieTyp) {
        View vie = LayoutInflater.from(par.getContext()).inflate(R.layout.fruit_item,par,false);
        final ViewHolder hol = new ViewHolder(vie);
        hol.fruitView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int pos = hol.getAdapterPosition();
                Fruit fru = mFruLis.get(pos);
                Toast.makeText(v.getContext(),"you clicked view" + fru.getName(),Toast.LENGTH_SHORT).show();
            }
        });
        hol.fruitImage.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int pos = hol.getAdapterPosition();
                Fruit fru = mFruLis.get(pos);
                Toast.makeText(v.getContext(),"you clicked image" + fru.getName(),Toast.LENGTH_SHORT).show();
            }
        });
        return hol;
    }

UI最佳实践：

public class Msg {
    public static final int TYPE_RECEIVED = 0;
    public static final int TYPE_SEND = 1;
    private String content;
    private int type;

    public Msg(String content,int type) {
        this.content = content;
        this.type = type;
    }

    public String getContent() {
        return content;
    }

    public int getType() {
        return type;
    }
}

public class MsgAdapter extends RecyclerView.Adapter {
    private List mMsgList;

    static class ViewHolder extends RecyclerView.ViewHolder {
        LinearLayout leftLayout;
        LinearLayout rightLayout;
        TextView leftMsg;
        TextView rightMsg;

        public ViewHolder(View view) {
            super(view);
            leftLayout = (LinearLayout) view.findViewById(R.id.left_layout);
            rightLayout = (LinearLayout) view.findViewById(R.id.right_layout);
            leftMsg = (TextView) view.findViewById(R.id.left_msg);
            rightMsg = (TextView) view.findViewById(R.id.right_msg);
        }
    }

    public MsgAdapter(List msgList) {
        mMsgList = msgList;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.msg_item,parent,false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Msg msg = mMsgList.get(position);
        if (msg.getType() == Msg.TYPE_RECEIVED) {
            holder.leftLayout.setVisibility(View.VISIBLE);
            holder.rightLayout.setVisibility(View.GONE);
            holder.leftMsg.setText(msg.getContent());
        } else if (msg.getType() == Msg.TYPE_SEND) {
            holder.rightLayout.setVisibility(View.VISIBLE);
            holder.leftLayout.setVisibility(View.GONE);
            holder.rightMsg.setText(msg.getContent());
        }
    }

    @Override
    public int getItemCount() {
        return mMsgList.size();
    }
}


String content = inputText.getText().toString();
                if (!"".equals(content)) {
                    Msg msg = new Msg(content,Msg.TYPE_SEND);
                    msgList.add(msg);
                    adapter.notifyItemInserted(msgList.size() - 1);
                    msgRecyclerview.scrollToPosition(msgList.size() - 1);
                    inputText.setText("");
                }

1.Fragment简单用法
建left和right的xml文件：

建立left和right的类：

public class Left extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inf, ViewGroup container, Bundle savedInstanceState) {
        View view = inf.inflate(R.layout.left,container,false);
        return view;
    }
}
public class Right1 extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inf, ViewGroup container, Bundle savedInstanceState) {
        View view = inf.inflate(R.layout.right1,container,false);
        return view;
    }
}

修改activity_main.xml：

动态添加Fragment：
建Right1.xml：

建Right1类：

public class Right1 extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inf, ViewGroup container, Bundle savedInstanceState) {
        View view = inf.inflate(R.layout.right1,container,false);
        return view;
    }
}

修改activity_main.xml：

修改MainActivity:

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) findViewById(R.id.button);
        replaceFragment(new Right());
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                replaceFragment(new Right1());
            }
        });
    }

    private void replaceFragment(Fragment fra) {
        FragmentManager fraMan = getSupportFragmentManager();
        FragmentTransaction tra = fraMan.beginTransaction();
        tra.replace(R.id.right_layout,fra);
        tra.commit();
    }
}

完成。

模拟返回栈：

tra.addToBackStack(null);

活动调用碎片中方法：

Right rigFra = (Right) getFragmentManager().findFragmentById(R.id.right);

碎片调用活动中方法：
在碎片中：

MainActivity act = (MainActivity) getActivity();

同时也可以使用这个方法获取Context。

fragment生命周期：onAttach(),onCreate(),onCreateView(),onActivityCreate(),onStart(),onResume(),onPause(),onStop(),onDestroyView(),onDestroy(),onDetach()

根据设备屏幕大小方向动态选择加载哪个布局：
修改activity_main.xml文件：

在res目录下新建layout_large文件夹,新建名为：activity_main.xml的布局：

最小宽度限定符：
新建layout-sw600dp文件夹，将上面第二个activity_main复制进去。

综合应用——新闻应用：
1。build.gradle 中添加recyclerview支持
2.新建新闻类：News

public class News {
    private String title;
    private String content;
    public String getTitle(){
        return title;
    }
    public void setTitle(String title){
        this.title = title;
    }
    public String getContent(){
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
}

3.新建内容布局文件news_content_frag.xml

4.新建内容布局类NewsContentFragment，继承Fragment:

public class NewsContentFragment extends Fragment {
    private View view;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.news_content_frag,container,false);
        return view;
    }

    public void refresh(String newsTitle,String newsContent) {
        View visibilityLayout = view.findViewById(R.id.visibility_layout);
        visibilityLayout.setVisibility(View.VISIBLE);
        TextView newsTitleText = (TextView)view.findViewById(R.id.news_title);
        TextView newsContentText = (TextView)view.findViewById(R.id.news_content);
        newsTitleText.setText(newsTitle);
        newsContentText.setText(newsContent);
    }
}

5.对小屏模式支持，新建Activity:NewsContentAcitivty和相应布局文件news_content.xml:

    

public class NewsContentActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.news_content);
        String newsTitle = getIntent().getStringExtra("news_title");
        String newsContent = getIntent().getStringExtra("news_content");
        NewsContentFragment newsContentFragment = (NewsContentFragment) getSupportFragmentManager().findFragmentById(R.id.news_content_fragment);
        newsContentFragment.refresh(newsTitle,newsContent);
    }

    public static void actionStart(Context context,String newsTitle,String newsContent) {
        Intent intent = new Intent(context,NewsContentActivity.class);
        intent.putExtra("news_title",newsTitle);
        intent.putExtra("new_content",newsContent);
        context.startActivity(intent);
    }
}

6.新建用于显示新闻列表的布局，news_title_frag.xml:

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


    

7.新建news_item.xml作为recyclerview的子布局：

8.新建NewsTitleFragment作为展示新闻列表的碎片：

public class NewsTitleFragment extends Fragment {
    private boolean isTwoPane;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.news_title_frag,container,false);
        RecyclerView newsTitleRecyclerView = (RecyclerView) view.findViewById(R.id.news_title_recycler_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
        newsTitleRecyclerView.setLayoutManager(layoutManager);
        NewsAdapter adapter = new NewsAdapter(getNews());
        newsTitleRecyclerView.setAdapter(adapter);
        return view;
    }

    private List getNews(){
        List newsList = new ArrayList<>();
        for(int i=1;i<=50;i++) {
            News news = new News();
            news.setTitle("This is news title" + i);
            news.setContent("content" + i);
            newsList.add(news);
        }
        return newsList;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        if (getActivity().findViewById(R.id.news_content_layout) != null) {
            isTwoPane = true;
        } else {
            isTwoPane = false;
        }
    }

    class NewsAdapter extends RecyclerView.Adapter {
        private List mNewsList;

        class ViewHolder extends RecyclerView.ViewHolder {
            TextView newsTitleText;
            public ViewHolder(View view) {
                super(view);
                newsTitleText = (TextView)view.findViewById(R.id.news_title);
            }
        }

        public NewsAdapter(List newsList) {
            mNewsList = newsList;
        }

        @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent,int viewType) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.news_item,parent,false);
            final ViewHolder holder = new ViewHolder(view);
            view.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    News news = mNewsList.get(holder.getAdapterPosition());
                    if (isTwoPane) {
                        NewsContentFragment newsContentFragment = (NewsContentFragment)getFragmentManager().findFragmentById(R.id.news_content_fragment);
                        newsContentFragment.refresh(news.getTitle(),news.getContent());
                        news.getContent();
                    } else {
                        NewsContentActivity.actionStart(getActivity(),news.getTitle(),news.getContent());
                    }
                }
            });
            return holder;
        }

        @Override
        public void onBindViewHolder(ViewHolder holder,int position) {
            News news = mNewsList.get(position);
            holder.newsTitleText.setText(news.getTitle());
        }

        @Override
        public int getItemCount() {
            return mNewsList.size();
        }
    }
}

9.修改activity_main.xml：

10.新建layout-sw600dp支持大屏，在此文件夹下新建activity_main：

关于广播

新建广播接收器：

class NetworkChangeReceiver extends BroadcastReceiver{
    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context,"network changes",Toast.LENGTH_SHORT).show();
    }
}

注册广播接收器：

private IntentFilter mIntentFilter;
private NetworkChangeReceiver mNetworkChangeReceiver;
    mIntentFilter = new IntentFilter();
    mIntentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
    mNetworkChangeReceiver = new NetworkChangeReceiver();
    registerReceiver(mNetworkChangeReceiver,mIntentFilter);

静态注册：

发送广播：

Intent intent = new Intent("com.lewanjiang.broadcasttest.MY_BORADCAST");
sendBroadcast(intent);

发送有序广播：

sendOrderedBroadcast(intent);

发送本地广播：

LocalBroadcastManager locBroMan = LocalBroadcastManager.getInstance(this);
Intent int = new Intent("com.lewanjiang.broadcasttest.LOCAL_BROADCAST");
locBroMan.sendBroadcast(int);

注册同普通广播一样，只是注销时：

locBroMan.unregisterReceiver(localReceiver);

强制下线功能实现：
1.新建ActivityCollector类和BaseActivity类：

public class ActivityCollector {
    public static List activities = new ArrayList<>();

    public static void addActivity(Activity activity) {
        activities.add(activity);
    }

    public static void removeActivity(Activity activity) {
        activities.remove(activity);
    }

    public static void finishAll() {
        for (Activity activity:activities) {
            if (!activity.isFinishing()) {
                activity.finish();
            }
        }
    }
}
public class BaseActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        ActivityCollector.removeActivity(this);
    }

2.新建一个空的Activity:LoginActivity，修改相应的activity_login.xml和LoginAcitivity:

    

        

        
    

    

        
        

    

    

public class LoginActivity extends BaseActivity {

    private EditText accountEdit;
    private EditText passwordEdit;
    private Button login;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        accountEdit = (EditText) findViewById(R.id.account);
        passwordEdit = (EditText) findViewById(R.id.password);
        login = (Button) findViewById(R.id.login);
        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String account = accountEdit.getText().toString();
                String password = passwordEdit.getText().toString();
                if (account.equals("admin") && password.equals("123456")) {
                    Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                    startActivity(intent);
                    finish();
                } else {
                    Toast.makeText(LoginActivity.this,"account or password wrong",Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

3.修改activity_main.xml：

4.修改MainActivity:

public class MainActivity extends BaseActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button forceOffline = (Button) findViewById(R.id.force_offline);
        forceOffline.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent("com.lewanjiang.broadcastbestpractice1.FORCE_OFFLINE");
                sendBroadcast(intent);
            }
        });
    }
}

5.注册广播接收器，修改BaseActivity如下：

public class BaseActivity extends AppCompatActivity {

    private ForceOfflineReceiver receiver;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
    }

    @Override
    protected void onResume(){
        super.onResume();
        IntentFilter intentFilter = new IntentFilter("com.lewanjiang.broadcastbestpractice1.FORCE_OFFLINE");
        receiver = new ForceOfflineReceiver();
        registerReceiver(receiver,intentFilter);
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (receiver != null) {
            unregisterReceiver(receiver);
            receiver=null;
        }
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        ActivityCollector.removeActivity(this);
    }

    class ForceOfflineReceiver extends BroadcastReceiver{
        @Override
        public void onReceive(final Context context, Intent intent) {
            AlertDialog.Builder builder = new AlertDialog.Builder(context);
            builder.setTitle("Warning");
            builder.setMessage("You are forced to be offline");
            builder.setCancelable(false);
            builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    ActivityCollector.finishAll();
                    Intent intent1 = new Intent(context,LoginActivity.class);
                    context.startActivity(intent1);
                }
            });
            builder.show();
        }
    }
}