# Total Sum for each category in an array

Solution for Total Sum for each category in an array
is Given Below:

I have an array that contains multiple items. The following is my array structure:

List ListCateory (

`````` ListName {
name = Salary;
amount = 40000;
date = 2020-05-01 16:00:00 +0000;
Category = Main Incomes;
Type = Income;
},
 ListName{
name = Diff;
amount =1500;
date = 2020-05-22 16:00:00 +0000;
Category= Misc;
Type = Expense;
},
 ListName{
name = Food;
amount =100;
date = 2020-05-18 16:00:00 +0000;
Category = Grocery;
Type = Expense;
},
 ListName{
name =  Food;
amount = 600;
date = 2020-05-24 16:00:00 +0000;
Category= Grocery;
Type = Expense;
}
 ListName{
name = Travel;
amount =400;
date = 2020-05-18 16:00:00 +0000;
Category = Travel;
Type = Expense;
},
``````

)

Below code am getting total income and expense

` Long totalExpense = 0l;
Long totalIncome = 0l;

``````    for (int i = 0; i < cexpenses.size(); i++) {

if (cexpenses.get(i).getType().contains("Income")  ) {
totalIncome += cexpenses.get(i).getAmount();
} else  if (cexpenses.get(i).getType().equals("Expense")  ) {
totalExpense += cexpenses.get(i).getAmount();
}
}

System.out.println("Expense " + totalExpense);
System.out.println("Income " + totalIncome);
``````

But am unable to get each Category total sum amount.The desired output is an array that will contain totals for each category like below:

`````` X-Array {
category = Main Incomes;
amount = XXXX;
};
 X-Array {
category = Grocery;
amount = XXXX;
};
``````

any help will be appreciate

Try this.

``````enum Category { MainIncomes, Misc, Grocery, Travel }
enum Type { Income, Expense }

record Item(String name, int amount, String date, Category category, Type type) {}

public static void main(String[] args) {
List<Item> list = List.of(
new Item("Salary", 40000, "2020-05-01 16:00:00 +0000", Category.MainIncomes, Type.Income),
new Item("Diff", 1500, "2020-05-22 16:00:00 +0000", Category.Misc, Type.Expense),
new Item("Food", 100, "2020-05-18 16:00:00 +0000", Category.Grocery, Type.Expense),
new Item("Food", 600, "2020-05-24 16:00:00 +0000", Category.Grocery, Type.Expense),
new Item("Travel", 400, "2020-05-18 16:00:00 +0000", Category.Travel, Type.Expense));
Map<Category, Integer> totalSum = list.stream()
.collect(Collectors.groupingBy(Item::category,
Collectors.summingInt(Item::amount)));
System.out.println(totalSum);
}
``````

output:

``````{Grocery=700, MainIncomes=40000, Misc=1500, Travel=400}
``````

You can use `class Item` instead of `record Item`.

``````public class Item {
String name;
int amount;
String date;
Category category;
Type type;

public Item(String name, int amount, String date, Category category, Type type) {
this.name = name;
this.amount = amount;
this.date = date;
this.category = category;
this.type = type;
}

public String name() { return name; }
public int amount() { return amount; }
public String date() { return date; }
public Category category() { return category; }
public Type type() { return type; }
}
``````

Lets say you have a list of expenses:

``````List<Expense> expenses = ...
``````

Firstly, group them by category, like this:

``````Map<String, List<Expense>> expensesByCategory =
expenses.stream().collect(Collectors.groupingBy(Expense::getCategory));
``````

Then, you can iterate over each category and do whatever you want, for example, calculate sum for each category:

``````for (String category : expensesByCategory.keySet()) {
List<Expense> categoryExpenses = expensesByCategory.get(category);
System.out.println(sum(categoryExpenses));
}
``````