Previously, I was saving the keys inside SharedPreferencesManager class using this way
public static final int KEY_COUNTRY_ID = 5,
KEY_COUNTRY_NAME = 10,
KEY_CURRENCY_ID = 15,
KEY_CURRENCY_NAME = 20;
I decided to use an enum to store the keys because I think it is a better way than the old way, Here is what I tried.
SharedPreferencesManager.java
public class SharedPreferencesManager {
private static SharedPreferences sharedPreferences;
private static SharedPreferences.Editor editor;
private static void initializeSharedPreferences(Context context) {
if (sharedPreferences == null)
sharedPreferences = context.getSharedPreferences("SharedPreferencesManager", Context.MODE_PRIVATE);
}
private static void initializeEditor() {
if (editor == null)
editor = sharedPreferences.edit();
}
public static void setValue(Context context, String key, int value) {
initializeSharedPreferences(context);
initializeEditor();
editor.putInt(key, value);
editor.apply();
}
public static int getIntegerValue(Context context, String key) {
initializeSharedPreferences(context);
switch (key) {
case Keys.COUNTRY_ID.name():
case Keys.CURRENCY_ID.name():
return sharedPreferences.getInt(key, 5);
}
return -1;
}
public enum Keys {
COUNTRY_ID,
COUNTRY_NAME,
CURRENCY_ID,
CURRENCY_NAME
}
}
The error
Constant expression required
The red lines under case Keys.COUNTRY_ID.name(): and case Keys.CURRENCY_ID.name():
How can I solve the problem?
>Solution :
As the compiler tells you, you need to use a constant String expression if you use switch(aStringVariable). The correct way to do this is to convert the String value to an enum constant and then use switch on that.
Convert the String to an enum instant using
Keys keyConstant = Keys.valueOf(key); //argument of "COUNTRY_ID" returns Keys.COUNTRY_ID
This looks up an enum constant by that name (matching the name()).
Then use it in the switch:
switch(keyConstant) {
case COUNTRY_ID: ...
}