Java uses only call by value while passing variables

ParameterPassingTest.java

package ir.soheil_gh;

public class ParameterPassingTest {

    public static void main(String[] args) {

        int a = 10;
        System.out.println("value of a before calling change method: " + a);
        change(a);
        System.out.println("value of a after calling change method: " + a);
        System.out.println();

        Person b = new Person(20);
        System.out.println("age of Person b before calling changeValueOfReference method: " + b.getAge());
        changeValueOfReference(b);
        System.out.println("age of Person b after calling changeValueOfReference method: " + b.getAge());
        System.out.println();

        Person c = new Person(20);
        System.out.println("age of Person c before calling changeInnerValue method: " + c.getAge());
        changeInnerValue(c);
        System.out.println("age of Person c after calling changeInnerValue method: " + c.getAge());


    }

    private static void change(int a){
        a = 5;
        System.out.println("value of a inside change method: " + a);
    }

    private static void changeValueOfReference(Person b){
        b = new Person(30);
        System.out.println("age of Person b inside changeValueOfReference method: " + b.getAge());
    }

    private static void changeInnerValue(Person c){
        c.setAge(30);
        System.out.println("age of Person c inside changeInnerValue method: " + c.getAge());
    }
}

class Person{
    private int age;

    public Person(int age) {
        this.age = age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getAge() {
        return age;
    }
}

output:

value of a before calling change method: 10
value of a inside change method: 5
value of a after calling change method: 10
 
age of Person b before calling changeValueOfReference method: 20
age of Person b inside changeValueOfReference method: 30
age of Person b after calling changeValueOfReference method: 20

age of Person c before calling changeInnerValue method: 20
age of Person c inside changeInnerValue method: 30
age of Person c after calling changeInnerValue method: 30