class A{
    private String name;

    private String value;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

    public A(String name){
        this.name = name;
    }

    @Override
    public String toString() {
        return "A{" +
                "name=‘" + name + ‘\‘‘ +
                ", value=‘" + value + ‘\‘‘ +
                ‘}‘;
    }
}
class B{
    private Object data;

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }

    @Override
    public String toString() {
        return "B{" +
                "data=" + data +
                ‘}‘;
    }
}
public class ThinkTest {
    public static void main(String[] args) {
        A a1 = new A("第一個A對象");
        System.out.println(a1);
        B b = new B();
        b.setData(a1);
        System.out.println(b);
        a1 = new A("第二個A對象");
        a1.setValue("success");
        System.out.print(b);
    }
}

A{name=‘第一個A對象‘, value=‘null‘}
B{data=A{name=‘第一個A對象‘, value=‘null‘}}
B{data=A{name=‘第一個A對象‘, value=‘null‘}}

java對象封裝的理解