Java 8 — Unary Operator | Code Factory

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• If input and output are same type then we should go for UnaryOperator
• It is child of Function<T, T>

Demo Program to find square of given integer by using Function :

package com.codeFactory.unaryOperator;
import java.util.function.Function;
public class Test {
 public static void main(String... args) {
  Function<Integer, Integer> f = i -> i * i;
  System.out.println(f.apply(3));
 }
}

Output :

9

Demo Program to find square of given integer by using UnaryOperator :

package com.codeFactory.unaryOperator;
import java.util.function.UnaryOperator;
public class Test {
 public static void main(String... args) {
  UnaryOperator<Integer> f = i -> i * i;
  System.out.println(f.apply(3));
 }
}

Output :

9

The primitive versions for UnaryOperator :

1. IntUnaryOperator

@FunctionalInterface
public interface IntUnaryOperator {
    int applyAsInt(int operand);
    default IntUnaryOperator compose(IntUnaryOperator before) { }
    default IntUnaryOperator andThen(IntUnaryOperator after) { }
    static IntUnaryOperator identity() { }
}

2. LongUnaryOperator

@FunctionalInterface
public interface LongUnaryOperator {
    long applyAsLong(long operand);
    default LongUnaryOperator compose(LongUnaryOperator before) { }
    default LongUnaryOperator andThen(LongUnaryOperator after) { }
    static LongUnaryOperator identity() { }
}

3. DoubleUnaryOperator

@FunctionalInterface
public interface DoubleUnaryOperator {
    double applyAsDouble(double operand);
    default DoubleUnaryOperator compose(DoubleUnaryOperator before) { }
    default DoubleUnaryOperator andThen(DoubleUnaryOperator after) { }
    static DoubleUnaryOperator identity() { }
}

Example 1 :

package com.codeFactory.unaryOperator;
import java.util.function.IntUnaryOperator;
public class Test {
 public static void main(String... args) {
  IntUnaryOperator u = i -> i * i;
  System.out.println(u.applyAsInt(3));
 }
}

Output :

9

Example 2 :

package com.codeFactory.unaryOperator;
import java.util.function.IntUnaryOperator;
public class Test {
 public static void main(String... args) {
  IntUnaryOperator u1 = i -> i + i;
  System.out.println(u1.applyAsInt(3));
  
  IntUnaryOperator u2 = i -> i * i;
  System.out.println(u2.applyAsInt(3));
  
  System.out.println(u1.andThen(u2).applyAsInt(3));
 }
}

Output :

6
9
36