JAVA List GroupBy multiple fields and Sum

I have list having fields Name, Currency and Amount.
I want to group it by Name, Currency and Sum of Amount.

List<myPojo> rows= ................

public class myPojo
{

    private String name;
    private String currency;
    private BigDecimal amount;

......................
}

I want result/output in list

You can use Stream API.
Use Collectors.toMap and use AbstractMap.SimpleEntry as key of map. Then define merge function for multiple values of the same key.

List<myPojo> res = new ArrayList<>(rows.stream()
.collect(Collectors.toMap(
e -> new AbstractMap.SimpleEntry<>(e.getName(), e.getCurrency()),
Function.identity(),
(a, b) -> new myPojo(a.getName(), a.getCurrency(), a.getAmount().add(b.getAmount()))))
.values());

Demo:

List<myPojo> list = new ArrayList<>();
list.add(new myPojo("A", "USD", new BigDecimal(1.0)));
list.add(new myPojo("A", "USD", new BigDecimal(2.0)));
list.add(new myPojo("A", "USD", new BigDecimal(3.0)));
list.add(new myPojo("B", "USD", new BigDecimal(1.0)));
list.add(new myPojo("B", "USD", new BigDecimal(2.0)));
list.add(new myPojo("B", "USD", new BigDecimal(3.0)));
list.add(new myPojo("A", "US", new BigDecimal(1.0)));
list.add(new myPojo("A", "US", new BigDecimal(2.0)));
list.add(new myPojo("A", "US", new BigDecimal(3.0)));
List<myPojo> res = new ArrayList<>(list.stream()
.collect(Collectors.toMap(
e -> new AbstractMap.SimpleEntry<>(e.getName(), e.getCurrency()),
Function.identity(),
(a, b) -> new myPojo(a.getName(), a.getCurrency(), a.getAmount().add(b.getAmount()))))
.values());
System.out.println(res.toString());

Output:

[myPojo [name=B, currency=USD, amount=6], 
myPojo [name=A, currency=USD, amount=6], 
myPojo [name=A, currency=US, amount=6]]

Note: Try to capitalize the name of the class like MyPojo for better convention

You could use groupingBy to generate a Map<String,Map<String,BigDecimal>> corresponding to Map<Name,Map<Currency,sum of Amount>>

List<myPojo> rows = List.of(new myPojo("ABCD", "USD", new BigDecimal(20)),
new myPojo("XYZ",  "GBP", new BigDecimal(60)),
new myPojo("XYZ",  "THB", new BigDecimal(35)),
new myPojo("ABCD", "INR", new BigDecimal(90)),
new myPojo("ABCD", "USD", new BigDecimal(80)),
new myPojo("XYZ",  "THB", new BigDecimal(45)));
Map<String,Map<String,BigDecimal>> map = 
rows.stream()
.collect(Collectors.groupingBy(myPojo::getName,
Collectors.groupingBy(myPojo::getCurrency,
Collectors.reducing(BigDecimal.ZERO, myPojo::getAmount, BigDecimal::add))));
System.out.println(map);
// output: {XYZ={GBP=60, THB=80}, ABCD={USD=100, INR=90}}