Change value of R.string programmatically

问题:

I have declared a string in my strings.xml file , and using it in my activity as R.string.compose_title. (setting it as title i.e. setTitle(R.id.compose_title)). Now in some case I want to edit the string and then use it to set the title . How can I do this ?

P.S. I need to change value of a single string only , So declaring a new strings.xml for each case(which are variable depending upon the user) using localization seems to be a lil inefficient .

回答1:

One thing what you have to understand here is that, when you provide a data as a Resource, it can\'t be modified during run time. For example, the drawables what you have in your drawable folder can\'t be modified at run time. To be precise, the \"res\" folder can\'t be modified programatically.

This applies to Strings.xml also, i.e \"Values\" folder. If at all you want a String which has to be modified at runtime, create a separate class and have your strings placed in this Class and access during run time. This is the best solution what I have found.

回答2:

I don\'t think you can programmatically customize the R class as it is built by ADT automatically.

回答3:

example howto:

how? by changing one variable reference to other reference

usage:

setRColor(pl.mylib.R.class,\"endColor\",pl.myapp.R.color.startColor);
// override app_name in lib R class  
setRString(pl.mylib.R.class,\"app_name\",pl.myapp.R.string.app_name);

base methods:

public static void setRColor(Class rClass, String rFieldName, Object newValue) {
    setR(rClass, \"color\", rFieldName, newValue);
}

public static void setRString(Class rClass, String rFieldName, Object newValue) {
    setR(rClass, \"string\", rFieldName, newValue);
}

// AsciiStrings.STRING_DOLAR = \"$\";
public static void setR(Class rClass, String innerClassName, String rFieldName, Object newValue) {
    setStatic(rClass.getName() + AsciiStrings.STRING_DOLAR  + innerClassName, rFieldName, newValue);
}

helper methods :

public static boolean setStatic(String aClassName, String staticFieldName, Object toSet) {
    try {
        return setStatic(Class.forName(aClassName), staticFieldName, toSet);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
        return false;
    }
}

public static boolean setStatic(Class<?> aClass, String staticFieldName, Object toSet) {
    try {
        Field declaredField = aClass.getDeclaredField(staticFieldName);
        declaredField.setAccessible(true);
        declaredField.set(null, toSet);
        return true;
    } catch (Exception e) {
        e.printStackTrace();
        return false;
    }
}

@bradenV2 My app is supporting many languages , so I wanted to take a string from my strings.xml that\'s currently in use and change that , and then use that one – atuljangra Mar 12 \'12 at 22:04

ps the above solution is good for example when u want to inject some data in already compiled lib/jar. But if u want localize strings just make folder under res per LANG CODE like values-CC where cc is lang code (values-de,values-cs) etc

then u have 2 choices:

1. \"build in\" system dependent language selection - based on device selected lang
2. via create resources for configuration - you decide which lang show

like this:

configuration = new Configuration(resources.getConfiguration());
configuration.setLocale(targetLocale);
String localized = Context.createConfigurationContext(configuration)
    .getResources()
    .getString(resourceId);

回答4:

I had a situation like this, where one of my strings.xml values had some dynamic piece of it. I set up the strings.xml with a \"replacement text\" (something like %%REPLACEMENT_EMAIL%%), and when I wanted to use that string programatically, I retrieved the string value of the resource, and replaced instances of that replacement text with the dynamic value (e.g. input by the user).

To be honest, my app has not been localized yet, but I\'m still attempting to follow best practices w.r.t. not hardcoding any strings.

回答5:

Maybe you want to \"modify\" the string.xml so when it is required by the activity again it uses the new value, for example to keep a new dynamic title after screen rotation.

First, you can\'t modify the resource. It\'s already compiled. You can\'t modify the R class (what for?) all it\'s atributes are \"final\".

So, for the example above you can use onSaveInstanceState() and onRestoreInstanceState() for those properties you wanna keep on display.

回答6:

According to my knowledge, you can\'t change resource value(R class value) while app running. why don\'t try to store on shared preference? I recommend you to use shared preference

回答7:

Use SharedPreferences inistead of a Java class. It will give you more versatility if you decide to take values from the outside (web). Filling Java class in runtime can be useless offline. In case of SharedPreferences you have to ensure they are loaded only once, during app\'s first start, and then updated only by manual request, as previous import will be used.

myActivity.getSharedPreferences(
  \"com.example.imported\",
  0)
.edit()
.putString(
  \"The news\",
  getTheNews())
.apply();