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android - 如何将自定义适配器中的数组列表保存到 SharedPreference

转载 作者:行者123 更新时间:2023-11-29 20:16:18 25 4
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我编写了显示已安装应用程序列表以及复选框的代码。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。我对此很陌生。所以,我要求提供详细的解决方案。另外,我还有一个问题。在这段代码中,复选框的状态保存在名为 checklist 的数组中。相反,是否可以创建名称等于 App 名称(我们从 PackageManager 获取)的 bool 变量,并且值将是复选框的状态。例如 bool 浏览器或 bool 相机。代码贴在下面。提前致谢!!

主 Activity .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);
}
}
}

应用适配器.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

<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>

行.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>

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

应用适配器.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,并且在我关闭应用程序后一切都会重置。我错过了什么?

编辑 1:根据新建议,我修改了自定义适配器。然而,即使我看到一些复选框已经被选中,它也是随机的。例如,如果我选中第 3 个复选框并重新打开 App,将选中第 2 个复选框而不是第 3 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?提前致谢..

最佳答案

通过共享首选项,您可以使用字符串作为键,使用 bool 值或任何其他原始数据类型作为值。

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,只需执行以下操作:

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

虽然 false 是您之前未保存此标签时获得的默认值(例如,未选中复选框)

此外,我建议您像这样设置复选框的事件监听器:

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

}
}
});

在获取 View 方法中,您可以直接访问您的数据源(ApplicationInfo List)。请注意,您随后必须将位置参数声明为最终参数。

编辑

您现在的问题似乎出在这一行:

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

虽然应用名称是您的 TextView 的标识符。因此,您的复选框的标签将设置为您的 textView 的字符串表示形式,这是一些调试信息。你可能是想:

checkBox.setTag(data);

我猜你的想法太复杂了。只需在您的获取 View 中尝试这个:

    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();
}
});

关于android - 如何将自定义适配器中的数组列表保存到 SharedPreference,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33845391/

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