尝试在 tomcat 9 上运行 gitblit，偶尔使用 JDK 11 会导致此堆栈跟踪：
gitblit | 07-May-2020 04:30:39.247 SEVERE [https-jsse-nio-8443-exec-10] org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun Error running socket processor
gitblit | java.lang.NullPointerException
gitblit | at java.base/sun.security.ssl.HKDF.extract(HKDF.java:93)
gitblit | at java.base/sun.security.ssl.HKDF.extract(HKDF.java:119)
gitblit | at java.base/sun.security.ssl.ServerHello.setUpPskKD(ServerHello.java:1167)
gitblit | at java.base/sun.security.ssl.ServerHello$T13ServerHelloProducer.produce(ServerHello.java:545)
gitblit | at java.base/sun.security.ssl.SSLHandshake.produce(SSLHandshake.java:436)
gitblit | at java.base/sun.security.ssl.ClientHello$T13ClientHelloConsumer.goServerHello(ClientHello.java:1234)
gitblit | at java.base/sun.security.ssl.ClientHello$T13ClientHelloConsumer.consume(ClientHello.java:1170)
gitblit | at java.base/sun.security.ssl.ClientHello$ClientHelloConsumer.onClientHello(ClientHello.java:852)
gitblit | at java.base/sun.security.ssl.ClientHello$ClientHelloConsumer.consume(ClientHello.java:813)
gitblit | at java.base/sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:392)
gitblit | at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:444)
gitblit | at java.base/sun.security.ssl.SSLEngineImpl$DelegatedTask$DelegatedAction.run(SSLEngineImpl.java:1061)
gitblit | at java.base/sun.security.ssl.SSLEngineImpl$DelegatedTask$DelegatedAction.run(SSLEngineImpl.java:1048)
gitblit | at java.base/java.security.AccessController.doPrivileged(Native Method)
gitblit …我遇到了一个问题,其中Lambda的允许语法在java编译器的1.8.0_05和1.8.0_20(beta)版本之间发生了变化.
例:
package scratch;
import javafx.scene.control.MenuItem;
public class Test
{
public void test()
{
MenuItem mi = new MenuItem();
//This compiles anywhere
mi.setOnAction(e -> System.out.println("hi"));
//as does this
mi.setOnAction(e -> {System.out.println("hi");});
//This doesn't on build 1.8.0_20-ea-b13 - but does on build 1.8.0_05-b13
mi.setOnAction(e -> (System.out.println("hi")));
}
}
我想知道的 - 最后一个例子是有效的Lambda表达式吗？他们刚刚收紧了编译器验证？或者最新的1.8编译器中是否有错误？
最新编译器打印的错误是:
/scratch/src/scratch/Test.java:18: error: method setOnAction in class MenuItem cannot be applied to given types;
mi.setOnAction(e -> (System.out.println("hi")));
^
required: EventHandler<ActionEvent>
found: (e)->(Syst[...]hi"))
reason: argument mismatch; bad return type in lambda …