I used the following piece of codes to generate SalesOrderLine numbers (sequential).
//creating lineNumber
int max = 0;
Integer lastNum = salesOrderLineDs.getItems().stream()
.map(SalesOrderLine::getLineNumberSo)
.max(Integer::compareTo)
.orElse(0);
line.setLineNumberSo(lastNum+1);
salesOrderLineDs.addItem(line);
It worked earlier but recently throes exception in V 6.4. The line number 87 in exception is this :
.max(Integer::compareTo)
java.lang.NullPointerException
at java.util.Objects.requireNonNull(Objects.java:203)
at java.util.Optional.<init>(Optional.java:96)
at java.util.Optional.of(Optional.java:108)
at java.util.stream.ReduceOps$2ReducingSink.get(ReduceOps.java:129)
at java.util.stream.ReduceOps$2ReducingSink.get(ReduceOps.java:107)
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.reduce(ReferencePipeline.java:479)
at java.util.stream.ReferencePipeline.max(ReferencePipeline.java:515)
at comcompany.web.sd.salesorder.SalesOrderEdit.onAdd(SalesOrderEdit.java:87)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.haulmont.cuba.gui.xml.DeclarativeAction.actionPerform(DeclarativeAction.java:84)
at com.haulmont.cuba.web.gui.components.WebButton.performAction(WebButton.java:45)
at com.haulmont.cuba.web.gui.components.WebButton.lambda$new$61446b05$1(WebButton.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:510)
at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:200)
at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:163)
at com.vaadin.server.AbstractClientConnector.fireEvent(AbstractClientConnector.java:1037)
at com.vaadin.ui.Button.fireClick(Button.java:377)
at com.haulmont.cuba.web.toolkit.ui.CubaButton.fireClick(CubaButton.java:54)
at com.vaadin.ui.Button$1.click(Button.java:54)
at sun.reflect.NativeMethodAccessorImpl.