Question

我注意到Kotlin合成属性在CustomViews上不起作用。我不知道是否有意。在读取生成的java类时，我看到缓存存在：

private HashMap _$_findViewCache;

但从未使用过。相反，只要需要视图，就会调用findViewById。这是默认行为吗？合成属性仅适用于活动和片段？

Answer 1

This works now. Blog post on kotlin-android-extensions

自定义类应生成缓存并使用它：

df <- structure(list(id = 10001:10010, 
                     period = structure(c(1L, 2L, 1L, 1L, 2L, 1L, 2L, 1L, 2L, 1L), 
                                        .Label = c("2017-01", "2017-02"), class = "factor"), 
                     year1 = c(2013, 2014, 2014, 2017, 1970, 2014, 1970, 2014, 2014, 1970), 
                     year2 = c(2015, NA, 2015, 2015, 1970, 1970, 2014, 2017, 2014, 2017), 
                     year3 = c(2015, 2014, 2015, NA, NA, 2014, 2014, 2015, 1970, 2014), 
                     year4 = c(1970, 2014, 2013, 2014, 1970, 1970, 2014, 2015, 2015, NA)), 
                .Names = c("id", "period", "year1", "year2", "year3", "year4"), 
                row.names = c(NA, -10L), 
                class = "data.frame")



library(reshape2)
dcast(melt(df[,-1]), period + variable ~ value)

#     period variable 1970 2013 2014 2015 2017 NA
# 1 2017-01    year1    1    1    3    0    1  0
# 2 2017-01    year2    1    0    0    3    2  0
# 3 2017-01    year3    0    0    2    3    0  1
# 4 2017-01    year4    2    1    1    1    0  1
# 5 2017-02    year1    2    0    2    0    0  0
# 6 2017-02    year2    1    0    2    0    0  1
# 7 2017-02    year3    1    0    2    0    0  1
# 8 2017-02    year4    1    0    2    1    0  0

这在自定义视图类中变为：

itemTitle.text = "Hello World!"

正确使用缓存

Kotlin合成特性

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