如何从 baseadaptor 获取共享偏好值到活动答案

【问题标题】：How to get shared preference value from baseadaptor to activity如何从 baseadaptor 获取共享偏好值到活动
【发布时间】：2017-05-08 11:34:28
【问题描述】：

从自定义列表视图中选择多个项目并传递给另一个列表显示。当我关闭应用程序时，这些选定的项目正在变得干净。

我使用了共享偏好，我无法获取数据> 主活动

MainActivity.java

public class MainActivity extends Activity {
private Button bt_inst_app;
GridView gridView, gv_shortcut;
List<AppList> installedApps;
List<AppList> res = new ArrayList<AppList>();
private String appName, appPackageName;
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_layout);
    gv_shortcut = (GridView) findViewById(R.id.gv_shortcut);
    bt_inst_app = (Button) findViewById(R.id.bt_inst_app);
    bt_inst_app.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            AlertDialog.Builder quick_links_alert = new AlertDialog.Builder(MainActivity.this);
            quick_links_alert.setTitle("Edit Quick Links");
            LinearLayout quick_links_layout = new LinearLayout(MainActivity.this);
            quick_links_layout.setOrientation(LinearLayout.VERTICAL);
            LinearLayout.LayoutParams quick_links_layoutparams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
            quick_links_layoutparams.setMargins(20, 0, 30, 0);
            gridView = new GridView(MainActivity.this);
            installedApps = getInstalledApps();
            final GridViewAdapter gridViewAdapter = new GridViewAdapter(MainActivity.this, installedApps);
            gridView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
            gridView.setAdapter(gridViewAdapter);
            gridView.setNumColumns(5);
            quick_links_alert.setView(gridView);
            quick_links_alert.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {
                    final List<AppList> mArrayProducts = gridViewAdapter.getCheckedItems();
                    final QuickLinksGridViewAdaptor selected_apps = new QuickLinksGridViewAdaptor(MainActivity.this, mArrayProducts);
                    gv_shortcut.setAdapter(selected_apps);
                    gv_shortcut.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                        @Override
                        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                            String s = mArrayProducts.get(position).getPackageName();
                            Intent PackageManagerIntent = getPackageManager().getLaunchIntentForPackage(s);//Here some time getting NULL
                            startActivity(PackageManagerIntent);
                        }
                    });
                }
            }).setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {
                }
            });
            quick_links_alert.show();

        }

        private List<AppList> getInstalledApps() {
            List<PackageInfo> packs = getPackageManager().getInstalledPackages(0);
            for (int i = 0; i < packs.size(); i++) {
                PackageInfo p = packs.get(i);
                //if ((isSystemPackage(p) == false)) {
                if (((p.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0) != true) {
                    appName = p.applicationInfo.loadLabel(getPackageManager()).toString();
                    Drawable icon = p.applicationInfo.loadIcon(getPackageManager());
                    appPackageName = p.applicationInfo.packageName;
                    res.add(new AppList(icon, appName, appPackageName));
                }
            }
            return res;
        }
    });
}
}

GridViewAdapter.java

   public class GridViewAdapter<T> extends BaseAdapter {
Context mContext;
//private final int length = 9;*/
private LayoutInflater layoutInflater;
List<AppList> listStorage;
MainActivity homeactivity;
private int selectedIndex;
private int selectedColor = Color.parseColor("#1b1b1b");
SparseBooleanArray mSparseBooleanArray;
SharedPreferences settings;
public GridViewAdapter(Context context, List<AppList> customizedListView) {
    layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    this.mContext = context;
    listStorage = customizedListView;
    mSparseBooleanArray = new SparseBooleanArray();
}
public void setSelectedIndex(int ind) {
    selectedIndex = ind;
    notifyDataSetChanged();
}
public ArrayList<T> getCheckedItems() {
    ArrayList<T> mTempArry = new ArrayList<T>();
    for (int i = 0; i < listStorage.size(); i++) {
        if (mSparseBooleanArray.get(i)) {
            mTempArry.add((T) listStorage.get(i));
        }
    }
    return mTempArry;
}
@Override
public int getCount() {
    return listStorage.size();
}
public Object getItem(int position) {
    return listStorage.get(position);
}
@Override
public long getItemId(int position) {
    return 0;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    final ViewHolder listViewHolder;
    if (convertView == null) {
        listViewHolder = new ViewHolder();
        LayoutInflater vi = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = vi.inflate(R.layout.add_apps_grid_item, parent, false);
        listViewHolder.textInListView = (TextView) convertView.findViewById(R.id.item_name);
        listViewHolder.imageInListView = (ImageView) convertView.findViewById(R.id.item_type);
        listViewHolder.tvPkgName = (TextView) convertView.findViewById(R.id.tvPack);
        listViewHolder.select_app = (CheckBox) convertView.findViewById(R.id.select_app);
        convertView.setTag(listViewHolder);
    } else {
        listViewHolder = (ViewHolder) convertView.getTag();
    }
    listViewHolder.textInListView.setText(listStorage.get(position).getName());
    listViewHolder.imageInListView.setImageDrawable(listStorage.get(position).getIcon());
    listViewHolder.tvPkgName.setText(listStorage.get(position).getPackageName());
    listViewHolder.select_app.setTag(position);
    listViewHolder.select_app.setChecked(mSparseBooleanArray.get(position));
    final AppList item = listStorage.get(position);
    listViewHolder.textInListView.setText(item.getName());
    SharedPreferences settings = mContext.getSharedPreferences("data", Context.MODE_PRIVATE);
    boolean Checked = settings.getBoolean(item.getName(), false);
    listViewHolder.select_app.setChecked(Checked);
    listViewHolder.select_app.setOnCheckedChangeListener(new OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            Toast.makeText(mContext, "pkg name==" + listStorage.get(position).getPackageName(), Toast.LENGTH_LONG).show();
            if (listViewHolder.select_app.isChecked() == true) {
                SharedPreferences settings = mContext.getSharedPreferences("data", Context.MODE_PRIVATE);
               // Toast.makeText(mContext, "You deselected " + Context.MODE_PRIVATE, Toast.LENGTH_SHORT).show();
                mSparseBooleanArray.put((Integer) buttonView.getTag(), settings.edit().putBoolean(item.getName(), true).commit());
               // Toast.makeText(mContext, "You selected " + item.getName(), Toast.LENGTH_SHORT).show();
            } else {
                SharedPreferences settings = mContext.getSharedPreferences("data", Context.MODE_PRIVATE);
                mSparseBooleanArray.put((Integer) buttonView.getTag(), settings.edit().putBoolean(item.getName(), false).commit());
               // Toast.makeText(mContext, "You deselected " + item.getName(), Toast.LENGTH_SHORT).show();
            }
           // Toast.makeText(mContext, "Shared prefernce---->" + mContext.toString(), Toast.LENGTH_SHORT).show();

        }
    });

    return convertView;
}
OnCheckedChangeListener mCheckedChangeListener = new OnCheckedChangeListener() {

    @Override
    public void onCheckedChanged(CompoundButton buttonView,
                                 boolean isChecked) {
        mSparseBooleanArray.put((Integer) buttonView.getTag(), isChecked);
    }

};
static class ViewHolder {
    TextView textInListView, tvPkgName;
    ImageView imageInListView;
    CheckBox select_app;
}
 }

AppList.java

public class AppList implements Parcelable {
private String name;
private String packageName;
Drawable icon;
private boolean selected;

public AppList(Drawable icon, String name, String packageName) {
    this.name = name;
    this.icon = icon;
    this.packageName = packageName;
}
protected AppList(Parcel in) {
    name = in.readString();
    packageName = in.readString();
    selected = in.readByte() != 0;
}
public static final Creator<AppList> CREATOR = new Creator<AppList>() {
    @Override
    public AppList createFromParcel(Parcel in) {
        return new AppList(in);
    }

    @Override
    public AppList[] newArray(int size) {
        return new AppList[size];
    }
};
public String getName() {
    return name;
}
public String getPackageName() {
    return packageName;
}
public Drawable getIcon() {
    return icon;
}
public String toString() {
    return name;
}
@Override
public int describeContents() {
    return 0;
}
@Override
public void writeToParcel(Parcel parcel, int i) {
    parcel.writeString(name);
    parcel.writeString(packageName);
    parcel.writeByte((byte) (selected ? 1 : 0));
}
public boolean isSelected() {
    return selected;
}
public void setSelected(boolean selected) {
    this.selected = selected;
}
 }

QuickLinksGridViewAdaptor.java

public class QuickLinksGridViewAdaptor<T> extends BaseAdapter {
private Context context;
//private final int length = 9;*/
private LayoutInflater layoutInflater;
List<AppList> listStorage;
MainActivity homeactivity;
private int selectedIndex;
SparseBooleanArray mSparseBooleanArray;
int num = 1;
public QuickLinksGridViewAdaptor(Context context, List<AppList> customizedListView) {
    layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    listStorage = customizedListView;
    mSparseBooleanArray = new SparseBooleanArray();
}
public void setSelectedIndex(int ind) {
    selectedIndex = ind;
    notifyDataSetChanged();
}
public ArrayList<T> getCheckedItems() {
    ArrayList<T> mTempArry = new ArrayList<T>();
    for (int i = 0; i < listStorage.size(); i++) {
        if (mSparseBooleanArray.get(i)) {
            mTempArry.add((T) listStorage.get(i));
        }
    }
    return mTempArry;
}
@Override
public int getCount() {
    //return 8;
    if(num*8 >= listStorage.size()){
        return listStorage.size();
    }else{
        return num*8;
    }
}
public Object getItem(int position) {
    return listStorage.get(position);
}
@Override
public long getItemId(int position) {
    return 0;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    ViewHolder listViewHolder;
    if (convertView == null) {
        listViewHolder = new ViewHolder();
        convertView = layoutInflater.inflate(R.layout.add_apps_grid_item1, parent, false);
        listViewHolder.textInListView = (TextView) convertView.findViewById(R.id.item_name1);
        listViewHolder.imageInListView = (ImageView) convertView.findViewById(R.id.item_type1);
        convertView.setTag(listViewHolder);

    } else {
        listViewHolder = (ViewHolder) convertView.getTag();
    }
    listViewHolder.textInListView.setText(listStorage.get(position).getName());
    listViewHolder.imageInListView.setImageDrawable(listStorage.get(position).getIcon());
    return convertView;
}
static class ViewHolder {
    TextView textInListView;
    ImageView imageInListView;
}
  }

【问题讨论】：

您在 sharedPreference 中将数据保存在哪里。我浏览了你的代码，但发现你只访问 sharedPref 中的数据而不是存储。
在 Gridview 适配器 "mContext.getSharedPreferences("data"
我可以知道如何获取共享偏好数据库适配器到活动

标签： android gridview sharedpreferences android-gridview

【解决方案1】：

您可以使用 savedInstanceState 方法在 Activity 中保存和检索数据，也可以在每次将选择的值（选择或非选择状态）更改为 SharedPreferences 时使用键作为名称/id 保存布尔检查值要选择的值，值是真还是假。

然后您可以轻松检查共享首选项，以检查此值是否存在于共享首选项中。并使用布尔值来显示选择。

希望你能得到这个答案。

【讨论】：

我检查真/假。我在基本适配器中获取数据。我知道如何将共享首选项数据库适配器获取到活动
您可以通过使用适配器中传递的活动的上下文来获取它
我是 android 新手...我得到 Null，但它不接受 Toast.makeText(MainActivity.this,"Shared Pref-->"+selected_apps.mContext,Toast.LENGTH_LONG)。显示（）;我可以知道我走的是正确的路吗？？
您可以通过在 MainActivity 类中任何需要的地方传递 MainActivity.this 作为上下文来访问 SharedPreferences。 SharedPreferences mSettings = getActivity().getSharedPreferences("Settings", Context.MODE_PRIVATE);
@Kumar 您可以访问此链接以更好地了解偏好guides.codepath.com/android/…