Android 通过来自 strings.xml 的值进行切换

Question

I'm new with Android and want to understand another one moment. I've got a strings.xml, which values I use in activity.xml. How use this values from JAva code in switch block?

private void gotoActivity(CharSequence text) {
    switch (text.toString()) {
        case getString(R.string.title_activity_first):
            break;

        case RADIO_BUTTON_SECCOND:
            break;
    }
}

Not compiles 'cos of "Constant expression required". But the main benefit of strings.xml - is string constants in one place.

Help plz.

Answer 1

Unfortunately you cannot use resource string in switch-case. You have two options. Choose anyone...

1. use static final String in your activity.

   Example: Initialize the strings

   public static final String TITLE_ACTIVITY_FIRST = "activity_title";

   public static final String RADIO_BUTTON_SECCOND = "radio_button_second";

   Then you can use the TITLE_ACTIVITY_FIRST in switch case. like,

    switch(text.toString()){ case TITLE_ACTIVITY_FIRST: break; case RADIO_BUTTON_SECOND: break; }

   No error will show!

2. use if-else. You can then use your resource strings.

   Example:

   if(text.toString().equals(getString(R.string.title_activity_first))){ //your code in case of 1st condition }else if(text.toString().equals(getString(R.string.title_activity_second))){ //your code in case of 2nd condition }

The second might look clumsy. But you wont have to change your code too much. Whereas the first one might look quite handy and you can easily modify later. Hope it helps!

Answer 2

你不能使用getString(R.string.title_activity_first)因为它从应用程序包的默认字符串表中返回一个本地化的字符串。所以结果会根据语言环境而不同，因此它不会是一个常量。你甚至不能使用 getString() 方法获取特定的本地字符串。最好使用静态最终字符串代替。请参阅此处