Hot questions for Operating ImmutableTable in Guava

Top 10 Java Open Source / Guava / Operating ImmutableTable

Java 8 collector for Guava Immutable Table

Question: Process list of string via method which returns ImmutableTable of type {R,C,V}. For instance ImmutableTable of {Integer,String,Boolean} process(String item){...}

Collect the result i.e, merge all results and return ImmutableTable. Is there a way to achieve it?

How about using parallel stream ? Is there any concurrency issues in the below code? With Parallel stream i an getting "NullPointerException at index 1800" on, but works fine with stream.

ImmutableTable<Integer, String, Boolean> buildData() {   

  // list of 4 AwsS3KeyName   

  //Create new instance via Guice dependency injection 
.map(s3KeyName -> ProcessorInstanceProvider.get()    

 return; }

While below code worksgreat with stream as well as parallel stream. But ImmutableBuild is failing due to duplicate entry for row and col. What could be the best way to prevent duplicates while merging tables ?

public static <R, C, V> Collector<ImmutableTable<R, C, V>,     
ImmutableTable.Builder<R, C, V>, ImmutableTable<R, C, V>>   
return Collector.of(ImmutableTable.Builder::new, 
ImmutableTable.Builder::putAll, (builder1, builder2) -> 
builder1.putAll(, ImmutableTable.Builder::build); }

Answer: Since Guava 21 you can use ImmutableTable.toImmutableTable collector.

public ImmutableTable<Integer, String, Boolean> processList(List<String> strings) {
            .flatMap(table -> table.cellSet().stream())
                    (b1, b2) -> b1 && b2 // You can ommit merge function!

private ImmutableTable<Integer, String, Boolean> processText(String text) {
    return ImmutableTable.of(); // Whatever