Question

如何在Android Studio上使用SharedPreferences保存一些数据，如布尔值？

SharedPreferences.Editor editor = getSharedPreferences(MY_PREFS_NAME,MODE_PRIVATE).edit();
    editor.putBoolean("firststart",false);
    editor.apply();
    SharedPreferences prefs = getSharedPreferences(MY_PREFS_NAME,MODE_PRIVATE);
    boolean firstStart= prefs.getBoolean("firststart",false);
    if (!firstStart) {
        Intent intent12 = new Intent(getApplicationContext(),FirstStart.class);
        startActivity(intent12);
        prefs.getBoolean("firststart",true);
    }
    else if (firstStart) {

    }

如果我每次创建活动时都使用此代码，则布尔值返回false，然后返回true。如何解决此问题并且不会丢失数据？

Answer 1

您不需要每次都将false保存为值，只要没有值，就会false prefs.getBoolean("firststart",false) true否则SharedPreferences.Editor editor = getSharedPreferences(MY_PREFS_NAME,MODE_PRIVATE).edit(); SharedPreferences prefs = getSharedPreferences(MY_PREFS_NAME,MODE_PRIVATE); boolean firstStart= prefs.getBoolean("firststart",false); if (!firstStart) { // save true during first time initialization Intent intent12 = new Intent(getApplicationContext(),FirstStart.class); startActivity(intent12); editor.putBoolean("firststart",true); editor.apply(); } // for second run, when you get true else if (firstStart) { }作为您的保存值

string query = "SELECT :p0, :p0 FROM DUMMY";
IDbCommand dbCommand = hanaConnection.CreateCommand();

dbCommand.CommandText = query;

IDataParameter param = dbCommand.CreateParameter();
param.Value = "A";
param.ParameterName = ":p0"; 

dbCommand.Parameters.Add(param);

hanaConnection.Open();

IDataReader dataReader = dbCommand.ExecuteReader();

while (dataReader.Read())
{
    ReadSingleRow((IDataRecord)dataReader);
}

Answer 2

实际上你的代码在每个onCreate上重置自己，所以你需要做的就是这样的

public class MyActivity extends Activity {

SharedPreferences prefs = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    prefs = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE);
}

@Override
protected void onResume() {
    super.onResume();

    if (prefs.getBoolean("firststart", true)) {
        // Do first run stuff here then set 'firstrun' as false
        // using the following line to edit/commit prefs
        prefs.edit().putBoolean("firststart", false).commit();
    }
  }
}

希望这会有所帮助

如何使用SharedPreferences？

2 个答案: