即使离开活动，如何保持多个复选框的选中状态?

Question

我真的需要一些帮助。即使搜索了几个小时并阅读了有关SharedPreferences的主题，我也无法解决我的问题。

我希望复选框(多个复选框！(保持选中/未选中状态，即使我离开活动。如果我返回到原始活动，复选框应处于与以前相同的状态。 这样您基本上可以将应用程序置于后台，如果您再次将其置于前台或转到其他活动，仍应选中/取消选中复选框(取决于用户检查的内容(。

这是我的活动代码.java：

public class TennisActivity extends AppCompatActivity {
//Variabeln
CheckBox cb118;
CheckBox cb119;
CheckBox cb120;
CheckBox cb121;
CheckBox cb122;
CheckBox cb123;
CheckBox cb149;
CheckBox cb150;
CheckBox cb151;
CheckBox cb152;
CheckBox cb153;
//Going back to menu by pressing back on device
@Override
public void onBackPressed() {
//super.onBackPressed();
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
Intent homeIntent = new Intent(TennisActivity.this, SportActivity.class);
startActivity(homeIntent);
finish();
}
}, 1);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_tennis);
//Variabeln initalisiern
cb118 = (CheckBox) findViewById(R.id.checkBox118);
cb119 = (CheckBox) findViewById(R.id.checkBox119);
cb120 = (CheckBox) findViewById(R.id.checkBox120);
cb121 = (CheckBox) findViewById(R.id.checkBox121);
cb122 = (CheckBox) findViewById(R.id.checkBox122);
cb123 = (CheckBox) findViewById(R.id.checkBox123);
cb149 = (CheckBox) findViewById(R.id.checkBox149);
cb150 = (CheckBox) findViewById(R.id.checkBox150);
cb151 = (CheckBox) findViewById(R.id.checkBox151);
cb152 = (CheckBox) findViewById(R.id.checkBox152);
cb153 = (CheckBox) findViewById(R.id.checkBox153);
}
}

提前感谢您的帮助！

Answer 1

使用"共享首选项"在用户切换复选框时保存当前状态。您可以在再次onCreate后从中重新加载数据。

要获取共享首选项：

SharedPreferences sharedPref = 
getActivity().getSharedPreferences("MY_SHARED_APPLICATIONS_NAME", Context.MODE_PRIVATE);

写：

SharedPreferences.Editor editor = sharedPref.edit();
editor.putBoolean("MY_BOOL_VARIABLE_KEY", myBoolVariable);
editor.commit();

阅读：

myBoolVariable = sharedPref.getBoolean("MY_BOOL_VARIABLE_KEY", defaultValue);

对于您的特定情况，您将需要一个键来识别每个复选框，如下所示：

private static final String cb118Key = "cb118_key";

然后在初始化复选框后，您应该根据SharedPreferences上保存的内容设置它们的状态：

cb118Checked = sharedPref.getBoolean(cb118Key, defaultValue);
cb118.setChecked(cb118Key);

唯一缺少的是当用户更改复选框状态时保存新状态：

cb118.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
editor.putBoolean(cb118Key, isChecked);
editor.commit();
}
});

Answer 2

将标志存储在共享首选项和检查值中。如果为 true，则设置检查，如以下代码。

String notif = pref.getString("notification", null);
if (notif != null && notif.equalsIgnoreCase("true")){
checkBoxNotification.setChecked(true);
}
checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (checkBoxn.isChecked()) {
notification = "true";
editor.putString("notification", notification).commit();
} else {
notification = "false";
editor.putString("notification", notification).commit();
}
}
});

Answer 3

感谢Natan，这是解决方案：(请注意，必须添加一些导入 - 通常是自动的 - 例如java.util.HashMap(

//Variabeln
CheckBox cb118;
CheckBox cb119;
CheckBox cb120;
CheckBox cb121;
CheckBox cb122;
CheckBox cb123;
CheckBox cb149;
CheckBox cb150;
CheckBox cb151;
CheckBox cb152;
CheckBox cb153;
//TRY
boolean myBoolVariable = false;
private static final String cb118Key = "cb118_key";
private static final String cb119Key = "cb119_key";
private static final String cb120Key = "cb120_key";
private static final String cb121Key = "cb121_key";
private static final String cb122Key = "cb122_key";
private static final String cb123Key = "cb123_key";
private static final String cb149Key = "cb149_key";
private static final String cb150Key = "cb150_key";
private static final String cb151Key = "cb151_key";
private static final String cb152Key = "cb152_key";
private static final String cb153Key = "cb153_key";
SharedPreferences sharedPref = null;

//Zurück zu SportActivity
@Override
public void onBackPressed() {
//super.onBackPressed();
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
Intent homeIntent = new Intent(TennisActivity.this, SportActivity.class);
startActivity(homeIntent);
finish();
}
}, 1);
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_tennis);
setContentView(R.layout.activity_main);

//Variabeln initalisiern
cb118 = (CheckBox) findViewById(R.id.checkBox118);
cb119 = (CheckBox) findViewById(R.id.checkBox119);
cb120 = (CheckBox) findViewById(R.id.checkBox120);
cb121 = (CheckBox) findViewById(R.id.checkBox121);
cb122 = (CheckBox) findViewById(R.id.checkBox122);
cb123 = (CheckBox) findViewById(R.id.checkBox123);
cb149 = (CheckBox) findViewById(R.id.checkBox149);
cb150 = (CheckBox) findViewById(R.id.checkBox150);
cb151 = (CheckBox) findViewById(R.id.checkBox151);
cb152 = (CheckBox) findViewById(R.id.checkBox152);
cb153 = (CheckBox) findViewById(R.id.checkBox153);
sharedPref = getSharedPreferences("alessionegrini.checkliste", Context.MODE_PRIVATE);
// I'll turn that into a map so it's easy to iterate over the values
Map<String, CheckBox> checkboxMap = new HashMap();
checkboxMap.put(cb118Key, cb118);
checkboxMap.put(cb119Key, cb119);
checkboxMap.put(cb120Key, cb120);
checkboxMap.put(cb121Key, cb121);
checkboxMap.put(cb122Key, cb122);
checkboxMap.put(cb123Key, cb123);
checkboxMap.put(cb149Key, cb149);
checkboxMap.put(cb150Key, cb150);
checkboxMap.put(cb151Key, cb151);
checkboxMap.put(cb152Key, cb152);
checkboxMap.put(cb153Key, cb153);
loadInitialValues(checkboxMap);
setupCheckedChangeListener(checkboxMap);
}
public void loadInitialValues(Map<String, CheckBox> checkboxMap) {
for (Map.Entry<String, CheckBox> checkboxEntry: checkboxMap.entrySet()) {
Boolean checked = sharedPref.getBoolean(checkboxEntry.getKey(), false);
checkboxEntry.getValue().setChecked(checked);
}
}
public void setupCheckedChangeListener(Map<String, CheckBox> checkboxMap) {
for (final Map.Entry<String, CheckBox> checkboxEntry: checkboxMap.entrySet()) {
checkboxEntry.getValue().setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
final SharedPreferences.Editor editor = sharedPref.edit();
editor.putBoolean(checkboxEntry.getKey(), isChecked);
editor.apply();
}
});
}
}}