当我将 Java 版本升级到 openJDK 11 时，加载模型映射器配置时出现 nullpointerException

Question

After upgrading Java version to openJDK 11, modelMapper configurations are not getting loaded, getting NullPointerException.

NullPointerException issue is not resolved even after upgrading modelMapper version to 2.3.2

Error Log:

1) Failed to configure mappings

Stack trace:

at org.modelmapper.internal.Errors.throwConfigurationExceptionIfErrorsExist(Errors.java:241)
    at org.modelmapper.internal.ExplicitMappingBuilder.build(ExplicitMappingBuilder.java:244)
    at org.modelmapper.internal.ExplicitMappingBuilder.build(ExplicitMappingBuilder.java:96)
    at org.modelmapper.internal.TypeMapImpl.addMappings(TypeMapImpl.java:92)
    at org.modelmapper.internal.TypeMapStore.getOrCreate(TypeMapStore.java:124)
    at org.modelmapper.ModelMapper.addMappings(ModelMapper.java:113)
    ...
Caused by: java.lang.NullPointerException
    at org.modelmapper.internal.ExplicitMappingBuilder$ExplicitMappingInterceptor.access$000(ExplicitMappingBuilder.java:304)
    at org.modelmapper.internal.ExplicitMappingBuilder.createAccessorProxies(ExplicitMappingBuilder.java:287)
    at org.modelmapper.internal.ExplicitMappingBuilder.createProxies(ExplicitMappingBuilder.java:277)
    at org.modelmapper.internal.ExplicitMappingBuilder.visitPropertyMap(ExplicitMappingBuilder.java:266)
    at org.modelmapper.PropertyMap.configure(PropertyMap.java:386)
    at jdk.internal.reflect.GeneratedMethodAccessor16.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at org.modelmapper.internal.ExplicitMappingBuilder.build(ExplicitMappingBuilder.java:227)
    ... 6 more

Answer 1

Internally ByteBuddy is throwing an exception which causes the issue, I will look into it a bit more to see if is perhaps a bug in ModelMapper.

Anyway check out the Java 8 tab at http://modelmapper.org/user-manual/property-mapping/ , your current code seems to be using the older documentation.

ModelMapper mm = new ModelMapper();

TypeMap<A, B> typeMap = mm.createTypeMap(A.class, B.class);
typeMap.addMappings(mapper -> {
    mapper.map(A::getDate, B::setTest);
    ... // Other mappings
});

This can convert Date -> Long out of the box without any other configuration. If you wish to configure it further you can always create custom Converters like so:

Converter<Date, Long> dateToLong = new AbstractConverter<Date, Long>() {
    @Override
    protected Long convert(Date source) {
        System.out.println("converting: " + source + " to " + source.getTime());
        return source.getTime();
    }
};

typeMap.addMappings(mapper -> mapper.using(dateToLong).map(A::getDate, B::setTest));

Answer 2

I had the same issue with modelmapper 2.3.0. Updated to latest 2.3.9 and issue was resolved