在我的 Android 应用程序中,我有设置 Activity ,它使用首选项。
有许多首选项,例如 ListPreference、SwitchPreference 等
,但没有一种我需要的首选项。
在此偏好中我想要:
1.显示一个恒定且永远不会改变的标题(例如其他首选项)
2. 显示文本,该文本将由应用程序更改,但不会由用户更改。
与此最相似的首选项是 EditTextPreference
,但这对我来说不好,因为我不希望用户更改显示的文本,而是我的应用程序会更改它。所以我的首选项可以称为 TextViewPreference
。
我想要的一个很好的例子是在“设置”Android 应用程序中的“设备信息”类别中。
编辑:
我想用来更改摘要的代码不会放置在 Activity 代码中,并且我不使用 PreferenceActivity
。
事实上,只有当 SettingsActivity 不在主线程上时,我才必须更改摘要。
最佳答案
下面的代码是您想要实现的目标的完整示例,它显示了如何创建基于其他首选项直接更新的信息首选项的示例(添加 x_pref 和 y_pref 并在下面的 result_pref 中显示结果)或根据从另一个 Activity 传递的内容进行更新。
1) 演示 Activity ----------
public class DemoActivity extends AppCompatActivity{
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.demo_activity);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.demo_preferences, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.menu_settings:
Intent i = new Intent(DemoActivity.this , PrefDemoActivity.class);
i.putExtra("Passed", "Test--##%%&&");
startActivity(i);
break;
default:
throw new RuntimeException("unknown menu selection");
}
return true;
}
}
2) demo_activity.xml----------
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="Empty"
android:gravity="center"
android:background="@android:color/holo_blue_light"/>
</android.support.constraint.ConstraintLayout>
3) PrefDemoActivity----------
public class PrefDemoActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FragmentManager mFragmentManager = getFragmentManager();
FragmentTransaction mFragmentTransaction = mFragmentManager
.beginTransaction();
DemoEditPreferences mDemoPrefsFragment = new DemoEditPreferences();
mFragmentTransaction.replace(android.R.id.content, mDemoPrefsFragment);
mFragmentTransaction.commit();
}
}
4) DemEditPreferences----------
public class DemoEditPreferences extends PreferenceFragment implements SharedPreferences.OnSharedPreferenceChangeListener{
private SharedPreferences demo_preferences;
private int preferencesToEdit;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
demo_preferences = getActivity().getSharedPreferences("demo_preference",
0);
preferencesToEdit = R.xml.demo_preferences;
String preferenceName = getResources().getString(R.string.pref_sensor_key);
PreferenceManager preferenceManager = getPreferenceManager();
preferenceManager.setSharedPreferencesName(preferenceName);
preferenceManager.setSharedPreferencesMode(0);
getActivity().setTitle("Demo Preferences");
addPreferencesFromResource(preferencesToEdit);
Preference from_another_activity_p = (Preference) findPreference("passed_from_another_activity_key");
if(getActivity().getIntent() != null) {
from_another_activity_p.setSummary(getActivity().getIntent().getStringExtra("Passed"));
}
updateResult();
for (int i = 0; i < getPreferenceScreen().getPreferenceCount(); i++) {
initSummary(getPreferenceScreen().getPreference(i));
}
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
if(findPreference(key) != null) {
if(findPreference(key).getKey().equals("x_key")) {
updateResult();
}else if(findPreference(key).getKey().equals("y_key")) {
updateResult();
}
checkPrefValueValidity(findPreference(key));
updatePrefSummary(findPreference(key));
}
}
private void updateResult(){
EditTextPreference x_p = (EditTextPreference) findPreference("x_key");
EditTextPreference y_p = (EditTextPreference) findPreference("y_key");
Preference result_p = (Preference) findPreference("result_key");
result_p.setSummary("( X + Y ) = " + (Float.valueOf(x_p.getText()) + Float.valueOf(y_p.getText())));
}
private void initSummary(Preference p) {
if (p instanceof PreferenceCategory) {
PreferenceCategory pCategory = (PreferenceCategory) p;
for (int i = 0; i < pCategory.getPreferenceCount(); i++) {
initSummary(pCategory.getPreference(i));
}
} else {
updatePrefSummary(p);
}
}
private void updatePrefSummary(Preference p) {
if (p instanceof ListPreference) {
ListPreference listPref = (ListPreference) p;
p.setSummary(listPref.getEntry());
}
if (p instanceof EditTextPreference) {
EditTextPreference editTextPref = (EditTextPreference) p;
p.setSummary(editTextPref.getText());
}
}
private void checkPrefValueValidity(Preference p) {
if (p instanceof EditTextPreference) {
EditTextPreference editTextPref = (EditTextPreference) p;
if (editTextPref.getText().equals("")) {
// what do you want to do if the value entered is empty
} else {
// maybe only certain values are allowed
}
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = super.onCreateView(inflater, container, savedInstanceState);
view.setBackgroundColor(getResources().getColor(android.R.color.white));
return view;
}
@Override
public void onResume() {
super.onResume();
getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
}
@Override
public void onPause() {
super.onPause();
getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
}
@Override
public void onDestroy() {
super.onDestroy();
getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
}
}
5) demo_menu----------
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/menu_settings"
android:title="Settings"
android:titleCondensed="Settings"
android:orderInCategory="1">
</item>
</menu>
7) demo_preferences----------
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory
android:title="Demo">
<EditTextPreference
android:key="x_key"
android:title="X"
android:defaultValue="0"
android:summary="0"
android:inputType="numberDecimal|numberSigned"
android:selectAllOnFocus="true"
android:singleLine="true">
</EditTextPreference>
<EditTextPreference
android:key="y_key"
android:title="Y"
android:defaultValue="0"
android:summary="0"
android:inputType="numberDecimal|numberSigned"
android:selectAllOnFocus="true"
android:singleLine="true">
</EditTextPreference>
<Preference
android:key="result_key"
android:title="Result"
android:summary="0"> // default summary value if any
</Preference>
<Preference
android:key="passed_from_another_activity_key"
android:title="From another Activity"
android:summary="null"> // default summary value if any
</Preference>
</PreferenceCategory>
</PreferenceScreen>
8) 不要忘记将这两个 Activity 添加到 list 中。
关于java - Android 偏好设置 如何进行信息偏好设置,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49518768/