Java没有引用传递机制，C#有。

Java没有引用传递机制，C#有：

public class Obj {
    private Integer myValue;

    public Integer getMyValue() {
        return myValue;
    }

    public void setMyValue(Integer myValue) {
        this.myValue = myValue;
    }
}

public class ObjOperation {
    public void changeValue(Obj obj) {
        obj.setMyValue(1);
    }
    
    public void changeValue2(Obj obj) {
        obj = new Obj();
        obj.setMyValue(2);
    }
}

public class MyApp {

    public static void main(String[] args) {
        Obj obj = new Obj();
        obj.setMyValue(0);
        System.out.println(obj.getMyValue());
        
        ObjOperation refOperation = new ObjOperation();
        
        refOperation.changeValue(obj);
        System.out.println(obj.getMyValue());
        
        refOperation.changeValue2(obj);
        System.out.println(obj.getMyValue());
    }

}

运行结果：

0
1
1

    public class Obj
    {
        private int myValue;
        public int MyValue { get => myValue; set => myValue = value; }
    }

    public class ObjOperation
    {
        public void ChangeValue(Obj obj)
        {
            obj.MyValue = 1;
        }

        public void ChangeValue2(Obj obj)
        {
            obj = new Obj();
            obj.MyValue = 2;
        }

        /// <summary>
        /// 引用传递
        /// </summary>
        /// <param name="obj"></param>
        public void ChangeValue3(ref Obj obj)
        {
            obj = new Obj();
            obj.MyValue = 2;
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            Obj obj = new Obj();
            obj.MyValue = 0;
            Console.WriteLine(obj.MyValue);

            ObjOperation objOperation = new ObjOperation();
            objOperation.ChangeValue(obj);
            Console.WriteLine(obj.MyValue);

            objOperation.ChangeValue2(obj);
            Console.WriteLine(obj.MyValue);

            //引用传递
            objOperation.ChangeValue3(ref obj);
            Console.WriteLine(obj.MyValue);

            Console.Read();
        }
    }

运行结果：

0
1
1
2