NoSuchMethodError: String.isEmpty [duplicate]

This question already has answers here: Closed 10 years ago.

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Scala on Android: java.lang.NoSuchMethodError: java.lang.String.isEmpty

I've just released a new app on Android

I've optimized and obfuscated the code with proguard and tested extensively on my Android 2.3.3 phone. It works all right.

However, I keep getting really strange crash reports in the developer console, such as

java.lang.NoSuchMet开发者_如何学编程hodError: java.lang.String.isEmpty

Isn't String.isEmpty() a framework function on all Android devices?

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There is TextUtils.isEmpty("your_String");, but haven't seen about your_string.isEmpty()

I found that your_string.isEmpty() works after 2.2 as it was added in 2.3 GingerBread. But, before that you can use TextUtils.isEmpty()