java - GWT 2.8 编译器警告

Question

当我从 GWT 2.7 切换到 2.8 时，我开始收到以下警告。我正在使用 ant 和 Oracle Java 7 从命令行进行编译。当我切换回 GWT 2.7 时，我没有收到任何这些警告

                           [WARN] Ignoring unresolvable annotation type java.lang.FunctionalInterface
 [java]    Resolving java.lang.Runnable
 [java]       Found type 'java.lang.Runnable'
 [java]          [WARN] Ignoring unresolvable annotation type java.lang.FunctionalInterface
 [java]    Resolving java.util.Arrays
 [java]       Found type 'java.util.Arrays'
 [java]          Resolving method parallelPrefix
 [java]             Found type 'java.util.function.BinaryOperator'
 [java]                [WARN] Ignoring unresolvable annotation type java.lang.FunctionalInterface
 [java]                Found type 'java.util.function.BiFunction'
 [java]                   [WARN] Ignoring unresolvable annotation type java.lang.FunctionalInterface
 [java]          Resolving method setAll
 [java]             Found type 'java.util.function.IntFunction'
 [java]                [WARN] Ignoring unresolvable annotation type java.lang.FunctionalInterface
 [java]          Resolving method stream
 [java]             Found type 'java.util.stream.Stream'
 [java]                Resolving method collect
 [java]                   Found type 'java.util.stream.Collector'
 [java]                      Resolving method supplier
 [java]                         Found type 'java.util.function.Supplier'
 [java]                            [WARN] Ignoring unresolvable annotation type java.lang.FunctionalInterface
 [java]                      Resolving method accumulator
 [java]                         Found type 'java.util.function.BiConsumer'
 [java]                            [WARN] Ignoring unresolvable annotation type java.lang.FunctionalInterface
 [java]                Resolving method flatMapToDouble
 [java]                   Found type 'java.util.stream.DoubleStream'
 [java]                      Resolving method collect
 [java]                         Found type 'java.util.function.ObjDoubleConsumer'
 [java]                            [WARN] Ignoring unresolvable annotation type java.lang.FunctionalInterface
 [java]                      Resolving method flatMap
 [java]                         Found type 

Answer 1

java.lang.FunctionalInterface 是在 Java 8 中添加的，GWT 从类路径解析注解，因此，由于 Java Runtime Emulation 库已更新到 Java 8，当将 GWT 2.8 与 Java 7 VM 结合使用。

因为 Java 7 已经 EOL 一段时间了，所以在这种情况下出现这些警告被认为是可以接受的。独立于 GWT，我们鼓励您迁移到 Java 8。