Java `IntPredicate`

the interface is a **Predicate with one int-valued argument**. The *IntPredicate* can be considered an operator or function that **returns a value either true or false based on certain evaluations of the argument **.

*int*value

*IntPredicate*?

1. How to Create and Use Technically `IntPredicate`

is a functional interface whose functional method is `boolean test(int a)`

.

Suppose we want to write a function to **check if a given number is an odd number** then we can do it in one line statement. Optionally, we can write a function (more specifically a predicate) that will test the argument number and check if it is an odd number.

In case of an odd number, the method will return ‘*true*‘ else ‘*false*‘.

`IntPredicate isOddNumber = argument -> argument % 2 == 1;`

Now we can **use the Predicate with Stream of Integer-type elements**.

```
IntStream stream = IntStream.range(1, 10);
List<Integer> oddNumbers = stream.filter(isOdd)
.boxed()
.collect(Collectors.toList()); //[1, 3, 5, 7, 9]
```

We can also use the **predicate to test individual integer values** as well.

```
System.out.println( isOdd.test(9) ); //true
System.out.println( isOdd.test(10) ); //false
```

*IntPredicate*

2. Using Complex Suppose we do not have a very simple condition to evaluate. Rather we have a few independent conditions which shall be evaluated in combination. For example, we want to **find all odd numbers less than 20 which are prime numbers as well**.

Here, we can define two predicates independently and combine their usage to check if both conditions satisfy. To combine two predicates, use the below functions:

– Returns a composed predicate that represents a*IntPredicate and(IntPredicate other)***short-circuiting logical AND**of this predicate and another.– Composed predicate represents a*IntPredicate or(IntPredicate other)***short-circuiting logical OR**of this predicate and another.

It also provides `IntPredicate negate()`

method which returns a predicate that represents the logical negation of this predicate.

```
import java.util.List;
import java.util.function.IntPredicate;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
public class IntPredicateExample
{
public static void main(String[] args)
{
IntPredicate isOdd = argument -> argument % 2 == 1;
IntStream stream = IntStream.range(1, 20);
List<Integer> oddPrimes = stream.filter( isOdd.and(IntPredicateExample::isPrime) )
.boxed()
.collect(Collectors.toList());
System.out.println(oddPrimes);
}
public static boolean isPrime(int i)
{
IntPredicate isDivisible = index -> i % index == 0;
return i > 1 && IntStream.range(2, i).noneMatch(isDivisible);
}
}
```

Program output.

`[3, 5, 7, 11, 13, 17, 19]`

## 3. Conclusion

In this short Java tutorial, we introduced the *IntPredicate* class that is used to test the integer type values. We learned to combine multiple predicates to create complex predicates for more complex conditions.

Happy Learning !!

## Comments