java - 保存动态创建的复选框的状态

Question

我目前正在尝试制作一个简单的任务 killer 以用于学习目的，我创建了一个 ListView ，显示所有用户安装的带有复选框的应用程序，以便用户可以选择在屏幕关闭时应杀死的应用程序。

但我不知道如何保存复选框状态并获取选中的应用程序的包名称

我已经搜索堆栈溢出很长时间了，但仍然不知道该怎么办，请帮助我，谢谢

这是我的代码

AppAdapter.java

public class AppAdapter extends BaseAdapter {

private LayoutInflater layoutInflater;
private List<AppList> listStorage;

public AppAdapter(Context context, List<AppList> customizedListView) {
    layoutInflater =(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    listStorage = customizedListView;
}

@Override
public int getCount() {
    return listStorage.size();
}

@Override
public Object getItem(int position) {
    return position;
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(final int position, View convertView, ViewGroup parent) {

    final ViewHolder listViewHolder;
    if(convertView == null){
        listViewHolder = new ViewHolder();
        convertView = layoutInflater.inflate(R.layout.installed_app_list, parent, false);

        listViewHolder.textInListView = (TextView)convertView.findViewById(R.id.list_app_name);
        listViewHolder.imageInListView = (ImageView)convertView.findViewById(R.id.app_icon);
        listViewHolder.checkBox = (CheckBox)convertView.findViewById(R.id.checkBox);
        convertView.setTag(listViewHolder);

        listViewHolder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                if(isChecked){
                    listViewHolder.checkBox.setSelected(listStorage.get(position).isSelected());
                }
            }
        });
    }else{
        listViewHolder = (ViewHolder)convertView.getTag();
    }
    listViewHolder.textInListView.setText(listStorage.get(position).getName());
    listViewHolder.imageInListView.setImageDrawable(listStorage.get(position).getIcon());
    listViewHolder.checkBox.setChecked(listStorage.get(position).isSelected());

    return convertView;
}

static class ViewHolder{

    TextView textInListView;
    ImageView imageInListView;
    CheckBox checkBox;
}

}

Applist.java

public class AppList {

private String name;
Drawable icon;
private static final String PREFERENCES_NAMESPACE = "checkboxes_states";
boolean selected = false;
private SharedPreferences mSettings;
private SharedPreferences.Editor mEditor;

public AppList(Context context, String name, Drawable icon) {
    this.name = name;
    this.icon = icon;
    mSettings = context.getSharedPreferences(PREFERENCES_NAMESPACE, 0);
    mEditor = mSettings.edit();
    setSelected(mSettings.getBoolean(name, selected));
}

public String getName() {
    return name;
}

public Drawable getIcon() {
    return icon;
}
public boolean isSelected() {
    return selected;
}
public void setSelected(boolean selected) {
    if(this.selected != selected) { // update if changed
        mEditor.putBoolean(getName(), selected);
        mEditor.apply();
        this.selected = selected;
    }
}
}

MainActivity.java

public class MainActivity extends Activity {

Context context;

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

    context = getApplicationContext();

    ListView userInstalledApps = (ListView)findViewById(R.id.installed_app_list);

    List<AppList> installedApps = getInstalledApps();
    AppAdapter installedAppAdapter = new AppAdapter(MainActivity.this, installedApps);
    userInstalledApps.setAdapter(installedAppAdapter);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

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

    return super.onOptionsItemSelected(item);
}

private List<AppList> getInstalledApps() {
    List<AppList> res = new ArrayList<AppList>();
    List<PackageInfo> packs = getPackageManager().getInstalledPackages(0);
    for (int i = 0; i < packs.size(); i++) {
        PackageInfo p = packs.get(i);
        if ((isSystemPackage(p) == false)) {
            String appName = p.applicationInfo.loadLabel(getPackageManager()).toString();
            Drawable icon = p.applicationInfo.loadIcon(getPackageManager());
            res.add(new AppList(context, appName, icon));
        }
    }
    return res;
}

private boolean isSystemPackage(PackageInfo pkgInfo) {
    return ((pkgInfo.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0) ? true : false;
}
}

提前致谢

Answer 1

创建接口(interface):

    public interface AppSelector {
        void selectApp(String appName);
        void removeApp(String appName);
        boolean isSelected(String appName);
    }

将其添加到您的 AppAdapter:

    public class AppAdapter extends BaseAdapter {

    private AppSelector appSelector;
    private List<AppList> listStorage;

    public AppAdapter(AppSelector appSelector, List<AppList> customizedListView) {
        this.appSelector = appSelector;
        listStorage = customizedListView;
    }

    ....

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        final ViewHolder listViewHolder;
        if(convertView == null){
            listViewHolder = new ViewHolder();
            convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.installed_app_list, parent, false);

            listViewHolder.textInListView = (TextView)convertView.findViewById(R.id.list_app_name);
            listViewHolder.imageInListView = (ImageView)convertView.findViewById(R.id.app_icon);
            listViewHolder.checkBox = (CheckBox)convertView.findViewById(R.id.checkBox);
            convertView.setTag(listViewHolder);
            listViewHolder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                    if (isChecked) {
                        appSelector.selectApp(listStorage.get(position).getName());
                    } else {
                        appSelector.removeApp(listStorage.get(position).getName());
                    }
                }
            });
        } else {
            listViewHolder = (ViewHolder)convertView.getTag();
        }
        listViewHolder.textInListView.setText(listStorage.get(position).getName());
        listViewHolder.imageInListView.setImageDrawable(listStorage.get(position).getIcon());
        listViewHolder.checkBox.setChecked(appSelector.isSelected(listStorage.get(position).getName()));

        return convertView;
    }

    ....
}

通过您的 MainActivity 实现:

    class MainActivity extends AppCompatActivity implements AppSelector {

    private static final String PREFERENCES_NAMESPACE = "checkboxes_states";
    private SharedPreferences checkedAppsPreferences;

    ....

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ....
        checkedAppsPreferences = getSharedPreferences(PREFERENCES_NAMESPACE, 0);
        ....
        AppAdapter installedAppAdapter = new AppAdapter(this, installedApps);
        ....
    }

    @Override
    public void selectApp(String appName) {
        checkedAppsPreferences.edit()
            .putBoolean(appName, true)
            .apply();
    }

    @Override
    public void removeApp(String appName) {
        checkedAppsPreferences.edit()
            .remove(appName)
            .apply();
    }

    @Override
    public boolean isSelected(String appName) {
        return checkedAppsPreferences.contains(appName) && checkedAppsPreferences.getBoolean(appName, false);
    }

    ....
}

您的 AppList 类不应包含对 Context 或 SharedPreferences 的任何引用以及“检查”/“取消检查”的逻辑。它应该是简单的 POJO。

使用界面，您可以轻松地将共享首选项替换为另一种类型的存储库(例如 SQLite)

编辑:我更改 AppAdapter getView mwthod:

            listViewHolder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                if (isChecked) {
                    appSelector.selectApp(listStorage.get(position).getName());
                } else {
                    appSelector.removeApp(listStorage.get(position).getName());
                }
            }
        });

您可以在 https://github.com/valeragit/AppListExample 查看完整项目