recyclerView複用錯亂問題解決方案

實現效果

• 用checkBox實現單項選擇
• 當後臺殺掉應用後，重新進入應用顯示你後臺殺掉應用時的選項

問題描述

• 由於recyclerView採用複用的策略，在向下重新整理列表時候，移出視野的item物件會被複用到新的列表上導致點選事件錯亂。
• checkBox點選之間不互斥
• 顯示不出來殺掉應用前的選項

解決思路

1.recyclerView點選事件會複用錯亂。但是顯示的內容不會錯亂，可以知道position是不會錯亂的。
2.在我們的資料類中增加一個boolean的欄位selected用來記錄選中狀態。
3.在recyclerView中新增點選事件來改變selected的值，在初始化的時候正確的實現
4.在activity中定義int型別的mSelectedPos欄位，用來記錄上一個被點中的item的position實現checkBox的互斥事件

廢話不多說啦,上程式碼，會加註釋的（>.<）

1.activity類描述

public class MainActivity extends Activity {

    private List<AppInfo> mAppInfoList = new ArrayList<>();
    private int mSelectedPos = 0;//定義欄位記錄上一個點選的item位置，實現互斥
    private ListAdapter mAdapter;
    private RecyclerView mRecyclerView;
    private
 
 Handler mHandler = new Handler();

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

        mAdapter = new ListAdapter();
        mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview);
        mRecyclerView.setLayoutManager(new
 
 LinearLayoutManager(this));
        mRecyclerView.setAdapter(mAdapter);

        initData();

    }


    class ListAdapter extends RecyclerView.Adapter<ListAdapter.MyViewHolder> {

        @Override
        public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            MyViewHolder holder = new MyViewHolder(LayoutInflater.from(
                    MainActivity.this).inflate(R.layout.item_home, parent,
                    false));
            return holder;
        }

//每次滾動新增新的item時候都會輪詢執行下面的函式進行item的初始化
        @Override
        public void onBindViewHolder(final MyViewHolder holder, final int position) {
            holder.textView.setText(mAppInfoList.get(position).getAppName());
            holder.imageView.setImageDrawable(mAppInfoList.get(position).getIcon());
            holder.checkBox.setChecked(mAppInfoList.get(position).isSelected());//mAppInfoList就是我們要顯示的物件集合，集合裡面放的是AppInfo物件，AppInfo物件封裝了要顯示的圖片和文字資訊。重要的是加了一個布林型別的selected欄位。
            if (mAppInfoList.get(position).isSelected()) {
                mSelectedPos = position;//這個if語句配合著我們初始化資料集合使用，把我們退出應用前的item的appInfo例項的selected的欄位設為true，當我們在碰到為true的item就是我們退出應用前選擇的item，把它的position賦值給mSelectedPos.完成點選新的item時把原先的item的checkBox置為false。
            }
            holder.checkBox.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    mAppInfoList.get(mSelectedPos).setSelected(false);
                    //setting up a new Item checkout state
                    mSelectedPos = position;
                    mAppInfoList.get(mSelectedPos).setSelected(true);
                    notifyDataSetChanged();
                    SharedPreferences.Editor editor = WidgetUtil.getEditor(MainActivity.this);//WidgetUtil類是一個工具類，裡封裝了各種方法和欄位。這句話是獲得Editor物件，並把packageName值存進去
                    editor.putString(WidgetUtil.PACKAGE_NAME, mAppInfoList.get(position).getPackageName());
                    editor.putInt("radioId", position);
                    editor.commit();
                    Intent intent = new Intent();
                    intent.setAction(WidgetUtil.BINGING_ICON_ACTION);
                    sendBroadcast(intent);
                }
            });
        }

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

        class MyViewHolder extends RecyclerView.ViewHolder {
            TextView textView;
            ImageView imageView;
            CheckBox checkBox;

            public MyViewHolder(View view) {
                super(view);
                textView = (TextView) view.findViewById(R.id.id_num);
                imageView = (ImageView) view.findViewById(R.id.id_image);
                checkBox = (CheckBox) view.findViewById(R.id.id_check_box);
            }
        }

    }

    public ListAdapter getAdapter() {
        if (mAdapter == null) {
            return null;
        } else {
            return mAdapter;
        }
    }


    public void initData() {
        final Runnable mUpdateResults = new Runnable() {
            public void run() {
                mAdapter.notifyDataSetChanged();
            }
        };
        new Thread(new Runnable() {
            @Override
            public void run() {
                mAppInfoList = WidgetUtil.getAppsInfoList(MainActivity.this);
                mHandler.post(mUpdateResults);
            }
        }).start();
    }

}

2.工具類WidgetUtil原始碼

class WidgetUtil {

//這些欄位不必知道具體含義，只要關注我們怎麼實現互斥的就可以啦
    public static final String WIDGET_BUTTON_ACTION = "cn.byd.Widget_Button_Click";
    public static final String BINGING_ICON_ACTION = "com.byd.intent.action.BINGING_ICON";
    public static final String PACKAGE_ADDED_ACTION = "android.intent.action.PACKAGE_ADDED";
    public static final String PACKAGE_REMOVED_ACTION = "android.intent.action.PACKAGE_REMOVED";
    public static final String WIDGET_OPEN_APP_INFO = "widget_open_app_info";
    public static final String PACKAGE_NAME = "packageName";
    public static final String PACKAGE = "package";
    public static final String WIDGET_APP_NAME = "com.android.firstapp";

    //Get the package name of the system installed for all applications,
    // and return to the list of all the package names
    //這個函式主要目的是獲得系統的所有安裝app的資訊，並把安裝的app的包名、應用名字、圖示、版本封裝成AppInfo物件，並把AppInfo物件放入到集合中
    public static List<AppInfo> getAppsInfoList(Context context) {
        List<PackageInfo> packages = context.getPackageManager().getInstalledPackages(0);
        List<AppInfo> allAppInfo = new ArrayList<>();
        SharedPreferences share = context.getSharedPreferences(WIDGET_OPEN_APP_INFO, context.MODE_PRIVATE);
        Intent intent = new Intent(Intent.ACTION_MAIN, null);
        intent.addCategory(Intent.CATEGORY_LAUNCHER);
        for (int i = 0; i < packages.size(); i++) {
            AppInfo appInfo = new AppInfo();
            PackageInfo packageInfo = packages.get(i);
            //If non - system applications are used, add to "allAppInfo
            if ((packageInfo.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) == 0) {
                appInfo.setPackageName(packageInfo.packageName);
                appInfo.setAppName(packageInfo.applicationInfo.loadLabel(context.getPackageManager()).toString());
                appInfo.setVersionName(packageInfo.versionName);
                appInfo.setIcon(packageInfo.applicationInfo.loadIcon(context.getPackageManager()));
                appInfo.setSelected(false);//重點：預設把所有物件的selected設為false也就是說檢視上的item預設是沒有被選中。
                if (share.getString(PACKAGE_NAME,"a").equals(packageInfo.packageName)){
                    appInfo.setSelected(true);//重點整個if語句是為了記錄你在退出應用時候點選的item選項，在重新啟動應用時候把你退出前選擇的item重現設定為被選中狀態
                }
                allAppInfo.add(appInfo);//If non - system applications are used, add to "allAppInfo"
            }

        }
        return allAppInfo;
    }



    //Getting editor
    public static SharedPreferences.Editor getEditor(Context context) {
        SharedPreferences sharedPreferences = context.getSharedPreferences(WIDGET_OPEN_APP_INFO, context.MODE_PRIVATE);
        SharedPreferences.Editor mEditor = sharedPreferences.edit();
        return mEditor;
    }


}

3.AppInfo類分析

public class AppInfo implements Serializable {

    private String packageName;
    private String appName;
    private String versionName;
    private Drawable icon;
    private int ID;
    private boolean selected;//關注下這個欄位，其他就是普通的java bean沒有什麼好註釋的啦


    public int getID() {
        return ID;
    }

    public String getPackageName() {
        return packageName;
    }

    public String getAppName() {
        return appName;
    }

    public String getVersionName() {
        return versionName;
    }

    public Drawable getIcon() {
        return icon;
    }

    public boolean isSelected() {
        return selected;
    }

    public void setID(int ID) {
        this.ID = ID;
    }

    public void setPackageName(String packageName) {
        this.packageName = packageName;
    }

    public void setAppName(String appName) {
        this.appName = appName;
    }

    public void setVersionName(String versionName) {
        this.versionName = versionName;
    }

    public void setIcon(Drawable icon) {
        this.icon = icon;
    }

    public void setSelected(boolean selected) {
        this.selected = selected;
    }
}

整個程式碼的作用

整個程式碼是把手機中裝的app全部提取出來用recyclerView顯示出所裝應用的圖示和名字，並實現單項選擇。