在自定义表函数时，运行出现了此错误，具体报错如下：
log4j:WARN No appenders could be found for logger (org.apache.flink.api.java.typeutils.TypeExtractor). log4j:WARN Please initialize the log4j system properly. log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info. Exception in thread "main" org.apache.flink.table.api.ValidationException: List of column aliases must have same degree as table; the returned table of function 'split' has 1 columns, whereas alias list has 2 columns at org.apache.flink.table.operations.utils.factories.CalculatedTableFactory$FunctionTableCallVisitor.createFunctionCall(CalculatedTableFactory.java:116) at org.apache.flink.table.operations.utils.factories.CalculatedTableFactory$FunctionTableCallVisitor.unwrapFromAlias(CalculatedTableFactory.java:100) at org.apache.flink.table.operations.utils.factories.CalculatedTableFactory$FunctionTableCallVisitor.visit(CalculatedTableFactory.java:74) at org.apache.flink.table.operations.utils.factories.CalculatedTableFactory$FunctionTableCallVisitor.visit(CalculatedTableFactory.java:62) at org.apache.flink.table.expressions.Callexpression.accept(Callexpression.java:122) at org.apache.flink.table.operations.utils.factories.CalculatedTableFactory.create(CalculatedTableFactory.java:59) at org.apache.flink.table.operations.utils.OperationTreeBuilder.joinLateral(OperationTreeBuilder.java:367) at org.apache.flink.table.api.internal.TableImpl.joinLateralInternal(TableImpl.java:337) at org.apache.flink.table.api.internal.TableImpl.joinLateral(TableImpl.java:289) at org.apache.flink.table.api.internal.TableImpl.joinLateral(TableImpl.java:284) at udf.udfTest2_TableFunction.main(udfTest2_TableFunction.java:42)
原因：自定义类集成TableFunction时没有实现getResultType方法
如我们此时输出的是Row类型，我们就需要重写此方法
@Override
public TypeInformation getResultType() {
return Types.ROW(Types.STRING, Types.INT);
}
