//Test.java
public class Test {
    public static void main(String[] args)
    {
        Person ps = new Person();
        ps.setPerson(10,"yyy",new Address());
        ps.printPerson();
        Address ad = ps.getAddress();
        String n = ps.getName();
        n = "lll";
        //Person psCopy = ps;
 

        //psCopy.setPerson(11,"llll");
        ad.setAddress("Zhenjiang", "HangZhou");
        ps.printPerson();
    }

}

//Person.java

public class Person {

    private int age;
    private String name;
    private Address address;

    public void setPerson(int age, String name, Address address)
    {
        this
 
.age = age;
        this.name = name;
        this.address = address;
    }

    public String getName()
    {
        return this.name;
    }

    public Address getAddress()
    {
        return address;

    }




    public void printPerson()
    {
        System.out.println("name:,"+name);
        System.out
 
.println("age:,"+age);

        address.printAddress();
    }
}

//Address.java

public class Address {
    private String province;
    private String city;

    public Address()
    {
        province = "ShanDong";
        city = "JiNan";
    }



    public void setAddress(String province, String city)
    {
        this.province = province;
        this.city = city;
    }


    public void printAddress()
    {
        System.out.println("province:," + province);
        System.out.println("city:," + city);
    }
}

輸出結果：
name:,yyy
age:,10
province:,ShanDong
city:,JiNan
name:,yyy
age:,10
province:,Zhenjiang
city:,HangZhou
基本型別(String,int)傳遞的是值，自定義“類”傳遞的是引用。

修改Test.java檔案，再來看一下執行結果

public class Test {
    public static void main(String[] args)
    {
        Person ps = new Person();
        ps.setPerson(10,"yyy",new Address());
        ps.printPerson();
        changObject(ps);
        ps.printPerson();
    }
    public static void changObject(Person ps)
    {
        Address ad = ps.getAddress();
        String n = ps.getName();
        n = "lll";

        ad.setAddress("Zhenjiang", "HangZhou");
    }

}

輸出結果：
name:,yyy
age:,10
province:,ShanDong
city:,JiNan
name:,yyy
age:,10
province:,Zhenjiang
city:,HangZhou
可見函式引數傳遞時也遵照上面的規則。
Java中只有基本資料型別在棧區，自定義類放在堆區。

Person ps;//會在Java IDE報錯
Person ps = new Person();//不會報錯