How to correctly call the void method in main?

Question

Java

this is how i try to call :
System.out.println(real.increment(imaginary));

here is the error :

error: Class names, 'javac', are only accepted if annotation processing is explicitly requested
ComplexMain.java:14: error: incompatible types: void cannot be converted to Complex
                Complex res = real.increment(imaginary);

here is the method:
public void increment(Complex other) {
this.real += other.real;
this.imaginary += other.imaginary;
}


I tried like this:
System.out.println(increment(imaginary));

but alas, it doesn't work((

what's the right way?

Answer 1

Error in the line
Complex res = real.increment(imaginary);
and in
System.out.println(real.increment(imaginary));
the same error. The increment method returns void, and changes the internal value. void cannot be assigned to anything, and cannot be passed anywhere. You can consider it "emptiness", "nothing". The void method does not return anything, so its return value cannot be assigned anywhere.
You need to split this into different lines:

real.increment(imaginary);
System.out.println(real);