Creare un nuovo progetto android chiamato HelloPreferences
Creare un layout con tre bottoni, per visualizzare, modificare via user interface e modificare via codice le preferenze
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button android:id="@+id/buttonVisualizza"
android:text="Visualizza Preferenze"
android:layout_height="wrap_content"
android:layout_width="match_parent"></Button>
<Button android:id="@+id/buttonModifica"
android:text="Modifica Preferenze da UI"
android:layout_height="wrap_content"
android:layout_width="match_parent"></Button>
<Button android:id="@+id/buttonCambia"
android:text="Modifica Preferenze da codice"
android:layout_height="wrap_content"
android:layout_width="match_parent"></Button>
</LinearLayout>
Creare un file xml/prefs.xml con due campi, username e password
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory>
<EditTextPreference
android:summary="Inserisci il tuo username"
android:key="username"
android:title="Nome utente">
</EditTextPreference>
<EditTextPreference
android:summary="Inserisci la tua password"
android:key="password"
android:title="Password">
</EditTextPreference>
</PreferenceCategory>
</PreferenceScreen>
Creare una activity per la modifica delle preferenze e mapparla nel manifest
public class Preferenze extends PreferenceActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.prefs);
}
} <activity android:name=".Preferenze"
android:label="@string/app_name">
</activity>
Gestire nella activity principale gli eventi sul click dei pulsanti.
public class HelloPreferencesActivity extends Activity {
SharedPreferences preferences;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
preferences = PreferenceManager.getDefaultSharedPreferences(this);
setContentView(R.layout.main);
Button visualizza = (Button) findViewById(R.id.buttonVisualizza);
visualizza.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
String username = preferences.getString("username", "n/a");
String password = preferences.getString("password", "n/a");
Toast.makeText(
getApplicationContext(),
"Hai impostato username: " + username +
", password: "+ password,
Toast.LENGTH_LONG
).show();
}
});
Button cambia = (Button) findViewById(R.id.buttonCambia);
cambia.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Editor edit = preferences.edit();
String username = preferences.getString("username", "n/a");
StringBuffer buffer = new StringBuffer();
for (int i = username.length() - 1; i >= 0; i--) {
buffer.append(username.charAt(i));
}
edit.putString("username", buffer.toString());
edit.commit();
Toast.makeText(getApplicationContext(),
"Invertito user name.",
Toast.LENGTH_LONG
).show();
}
});
Button modifica = (Button) findViewById(R.id.buttonModifica);
modifica.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent intent = new Intent(getApplicationContext(), Preferenze.class);
startActivity(intent);
}
});
}
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