如何将customadapter中的arraylist保存到SharedPreference

Question

我编写的代码显示已安装的应用列表以及复选框。但是，当我关闭应用程序时，复选框值会重置。我了解到，通过使用共享首选项，我可以保存复选框的状态。但是我无法在我的项目中实现它。我对此很新。所以，我要求提供详细的解决方案。另外，我还有一个问题。在此代码中，复选框的状态保存在名为checklist的数组中。而是可以创建名称等于App name的布尔变量（我们从PackageManager获得），值将是checkbox的状态。例如 布尔浏览器或布尔相机。代码发布在下面。在此先感谢!!

MainActivity.java

public class MainActivity extends ListActivity {
    private PackageManager packageManager = null;
    private List<ApplicationInfo> applist = null;
    private ApplicationAdapter listadapter = null;

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

        packageManager = getPackageManager();

        new LoadApplications().execute();
    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);

        ApplicationInfo app = applist.get(position);
        try {
            Intent intent = packageManager
                    .getLaunchIntentForPackage(app.packageName);

            if (null != intent) {
                startActivity(intent);
            }
        } catch (ActivityNotFoundException e) {
            Toast.makeText(MainActivity.this, e.getMessage(),
                    Toast.LENGTH_LONG).show();
        } catch (Exception e) {
            Toast.makeText(MainActivity.this, e.getMessage(),
                    Toast.LENGTH_LONG).show();
        }
    }

    private List<ApplicationInfo> checkForLaunchIntent(List<ApplicationInfo> list) {
        ArrayList<ApplicationInfo> applist = new ArrayList<ApplicationInfo>();
        for (ApplicationInfo info : list) {
            try {
                if (null != packageManager.getLaunchIntentForPackage(info.packageName)) {
                    applist.add(info);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        return applist;
    }

    private class LoadApplications extends AsyncTask<Void, Void, Void> {
        private ProgressDialog progress = null;

        @Override
        protected Void doInBackground(Void... params) {
            applist = checkForLaunchIntent(packageManager.getInstalledApplications(PackageManager.GET_META_DATA));
            listadapter = new ApplicationAdapter(MainActivity.this,
                    R.layout.row, applist);

            return null;
        }

        @Override
        protected void onCancelled() {
            super.onCancelled();
        }

        @Override
        protected void onPostExecute(Void result) {
            setListAdapter(listadapter);
            progress.dismiss();
            super.onPostExecute(result);
        }

        @Override
        protected void onPreExecute() {
            progress = ProgressDialog.show(MainActivity.this, null,
                    "Loading application info...");
            super.onPreExecute();
        }

        @Override
        protected void onProgressUpdate(Void... values) {
            super.onProgressUpdate(values);
        }
    }
}

ApplicationAdapter.java

public class ApplicationAdapter extends ArrayAdapter<ApplicationInfo> {
    private List<ApplicationInfo> appsList = null;
    private Context context;
    private PackageManager packageManager;
    private ArrayList<Boolean> checkList = new ArrayList<Boolean>();

    public ApplicationAdapter(Context context, int textViewResourceId,
                              List<ApplicationInfo> appsList) {
        super(context, textViewResourceId, appsList);
        this.context = context;
        this.appsList = appsList;
        packageManager = context.getPackageManager();

        for (int i = 0; i < appsList.size(); i++) {
            checkList.add(false);
        }
    }

    @Override
    public int getCount() {
        return ((null != appsList) ? appsList.size() : 0);
    }

    @Override
    public ApplicationInfo getItem(int position) {
        return ((null != appsList) ? appsList.get(position) : null);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = convertView;
        if (null == view) {
            LayoutInflater layoutInflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = layoutInflater.inflate(R.layout.row, null);
        }

        ApplicationInfo data = appsList.get(position);
        if (null != data) {
            TextView appName = (TextView) view.findViewById(R.id.app_name);
            TextView packageName = (TextView) view.findViewById(R.id.app_package);
            ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);

            CheckBox checkBox = (CheckBox) view.findViewById(R.id.cb_app);
            checkBox.setTag(Integer.valueOf(position)); // set the tag so we can identify the correct row in the listener
            checkBox.setChecked(checkList.get(position)); // set the status as we stored it
            checkBox.setOnCheckedChangeListener(mListener); // set the listener

            appName.setText(data.loadLabel(packageManager));
            packageName.setText(data.packageName);
            iconview.setImageDrawable(data.loadIcon(packageManager));
        }
        return view;
    }
    CompoundButton.OnCheckedChangeListener mListener = new CompoundButton.OnCheckedChangeListener() {

        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            checkList.set((Integer)buttonView.getTag(),isChecked); // get the tag so we know the row and store the status
        }
    };
}

activity_main.xml中

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">

    </ListView>

</LinearLayout>

row.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <ImageView
        android:id="@+id/app_icon"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:scaleType="centerCrop"
        android:padding="3dp"
        android:src="@drawable/download" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center_vertical"
        android:orientation="vertical"
        android:paddingLeft="5dp" >

        <TextView
            android:id="@+id/app_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center_vertical"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/app_package"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center_vertical" />
    </LinearLayout>


    <CheckBox
        android:id="@+id/cb_app"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

修改 根据@Falco Winkler的建议，我修改了我的自定义适配器，如下所示。

ApplicationAdapter.java

import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;    

public class ApplicationAdapter extends ArrayAdapter<ApplicationInfo> {
    private List<ApplicationInfo> appsList = null;
    private Context context;
    private PackageManager packageManager;
    private SharedPreferences prefs;
    public ApplicationAdapter(Context context, int textViewResourceId,
                              List<ApplicationInfo> appsList) {
        super(context, textViewResourceId, appsList);
        this.context = context;
        this.appsList = appsList;
        packageManager = context.getPackageManager();
        prefs = context.getSharedPreferences("checkboxstate",Context.MODE_PRIVATE);
    }



    @Override
    public int getCount() {
        return ((null != appsList) ? appsList.size() : 0);
    }

    @Override
    public ApplicationInfo getItem(int position) {
        return ((null != appsList) ? appsList.get(position) : null);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = convertView;
        if (null == view) {
            LayoutInflater layoutInflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = layoutInflater.inflate(R.layout.row, null);
        }

        ApplicationInfo data = appsList.get(position);
        if (null != data) {
            TextView appName = (TextView) view.findViewById(R.id.app_name);
            TextView packageName = (TextView) view.findViewById(R.id.app_package);
            ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);

            CheckBox checkBox = (CheckBox) view.findViewById(R.id.cb_app);
            checkBox.setTag(String.valueOf(appName)); // set the tag so we can identify the correct row in the listener
            checkBox.setChecked(prefs.getBoolean(checkBox.getTag().toString(), false)); // set the status as we stored it

            checkBox.setOnClickListener(onclicklistener);
            appName.setText(data.loadLabel(packageManager));
            packageName.setText(data.packageName);
            iconview.setImageDrawable(data.loadIcon(packageManager));
        }
        return view;
}

    CheckBox.OnClickListener onclicklistener = new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            prefs.edit().putBoolean(v.getTag().toString(),((CheckBox)v).isChecked()).apply();

        }
    };
}

但是，复选框的值仍未保存，关闭应用程序后所有内容都会重置。我错过了什么？

EDIT1： 根据新建议，我修改了自定义适配器。但是，即使我看到一些复选框已经检查过，它也是随机的。例如，如果我选中第三个复选框并重新打开应用程序，则将选中第二个复选框而不是第三个复选框。此外，还会随机选择其他一些复选框。我在下面发布修改后的代码。

package com.example.monika.savenotification;

import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class ApplicationAdapter extends ArrayAdapter<ApplicationInfo> {
    private List<ApplicationInfo> appsList = null;
    private Context context;
    private PackageManager packageManager;
    public ApplicationAdapter(Context context, int textViewResourceId,
                              List<ApplicationInfo> appsList) {
        super(context, textViewResourceId, appsList);
        this.context = context;
        this.appsList = appsList;
        packageManager = context.getPackageManager();


    }



    @Override
    public int getCount() {
        return ((null != appsList) ? appsList.size() : 0);
    }

    @Override
    public ApplicationInfo getItem(int position) {
        return ((null != appsList) ? appsList.get(position) : null);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = convertView;
        if (null == view) {
            LayoutInflater layoutInflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = layoutInflater.inflate(R.layout.row, null);
        }

        final ApplicationInfo data = appsList.get(position);
        final SharedPreferences prefs = context.getSharedPreferences("checkboxstate", Context.MODE_PRIVATE);
        if (null != data) {
            TextView appName = (TextView) view.findViewById(R.id.app_name);
            TextView packageName = (TextView) view.findViewById(R.id.app_package);
            ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);

            CheckBox checkBox = (CheckBox) view.findViewById(R.id.cb_app);
            checkBox.setTag(data); // set the tag so we can identify the correct row in the listener


            checkBox.setChecked(prefs.getBoolean(data.packageName, false)); // set the status as we stored it


            checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                    prefs.edit().putBoolean(data.packageName, isChecked).apply();

                }
            });

            appName.setText(data.loadLabel(packageManager));
            packageName.setText(data.packageName);
            iconview.setImageDrawable(data.loadIcon(packageManager));
        }
        return view;
}


}

我还需要做哪些修改？提前谢谢..

Answer 1

使用共享首选项，您可以使用String作为键，使用布尔值或任何其他基本数据类型作为值。

所以在你的onClickListener中你可以这样做：

 SharedPreferences prefs = activity.getSharedPreferences(
                    "com.company.yourapp", Context.MODE_PRIVATE);

 prefs.edit().putBoolean(buttonView.getTag().toString, isChecked).apply();

如果您想确定复选框的状态，请执行以下操作：

prefs.getBoolean(yourTag.toString(), false);

虽然false是您之前未保存此标记时的默认值（例如，未选中该复选框）

另外，我建议您设置复选框的事件监听器，如下所示：

  checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            if (isChecked) {
                ApplicationInfo info = appsList.get(position);

            }
        }
    });

在get view方法中，您可以直接访问数据源（ApplicationInfo List）。请注意，您必须将position参数声明为final。

修改

现在你的问题似乎出现在这一行：

checkBox.setTag(String.valueOf(appName));

虽然app name是TextView的标识符。因此，复选框的标记将设置为textView的字符串表示形式，这是一些调试信息。你可能想：

checkBox.setTag(data);

我想你认为这很复杂。只需在获取视图中尝试此操作：

    final ApplicationInfo data = appsList.get(position);
    ...
    final SharedPreferences prefs = activity.getSharedPreferences(
            "com.company.yourapp", Context.MODE_PRIVATE);

    checkBox.setChecked(prefs.getBoolean(data.packageName, false));
    checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

            prefs.edit().putBoolean(data.packageName, isChecked).apply();
        }
    });