JAVA how to increment object argument?

Question

Java

I am interested in understanding how to write a method that, when called, will
ncrementA(c2.a);
incrementB(c2.b);
increase them.

I get some kind of nonsense (

Public class MyClass
{
private int a;
public double b;

public MyClass(int first, double second)
{
this.a = first;
this.b = second;
}

public static void incrementBoth(MyClass c1) {
c1.a = c1.a + 1;
c1.b = c1.b + 1.0;
}

// new method
public static void incrementA(int first)
{
first = first + 1;
}

// new method
public static void incrementB(double second)
{
second = second + 1.0;
}

public static void main(String[] args)
{
MyClass c1 = new MyClass(10, 20.5);
MyClass c2 = new MyClass(10, 31.5);
// different code below
incrementA(c2.a);
incrementB(c2.b);
System.out.println(c2.a + ", "+ c2.b);
}
}

Answer 1

Primitives are always passed by value
Only the argument is updated at this point

public static void incrementA(int first)
{
first = first + 1;
}

I wanted it like this:

public static void incrementA(int first)
{
this.first = first + 1;
}