代码如：

    if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD)
        ed.apply();
    else ed.commit();

在Froyo发出警告：

04-27 03:40:35.025: W/dalvikvm(3138): VFY: unable to resolve interface method 219: Landroid/content/SharedPreferences$Editor;.apply ()V

但据我所知,在较旧的设备中,这将是一个RuntimeError,它会中止应用程序(参见here和here).

那么有条件地在API 8(Froyo)及以上版本中有条件地调用新API(方法)的方式是否仍然需要延迟加载？

Dalvik有什么变化使这成为可能？

有关

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解决方法:

produces a warning in Froyo

这是完全正常的.

But I understand that in older devices this would be a RuntimeError which would abort the application

对于Android 1.x,是的.

So is this way of conditionally calling new API (methods) safe in API 8 (Froyo) and above

是.

What changes on Dalvik made this possible ?

遇到未识别的符号时,它不再“快速失败”,而是在执行语句时等待再次尝试解决它.通过检查SDK_INT并确保未执行该语句,您不会崩溃.