我有一个带有main方法的2个java类和一个带有私有变量的类。获取和设置的方法。所以,我的问题是我们可以在所有setter(3 setter)中使用相同的对象引用变量,并在所有getter(3)中使用不同的引用变量吗? 我用过那个,我得到了空值。
但是,当我使用3个不同的对象引用变量为3个getter和相同的3个对象引用变量for getters然后它工作正常。 那么,有人能解释我这个概念吗?
package project1;
public class Encapsulationjerry1 {
public static void main(String[] args)
{
System.out.println("Now, we are gonna test our Encapsulation");
// I gave different variables for all setters and same respective variables for getters. This is working fine.
Encapsulationtom1 obj1 = new Encapsulationtom1();
Encapsulationtom1 obj2 = new Encapsulationtom1();
Encapsulationtom1 obj3 = new Encapsulationtom1();
obj1.setDesignation("Lead Designer");
obj2.setEmployeeId(23452);
obj3.setEmployeeName("Meliodas");
System.out.println("The designation is "+ obj1.getDesignation());
System.out.println("The Employee Id is "+ obj2.getEmployeeId());
System.out.println("The Employee Name is "+ obj3.getEmployeeName());
// But when i give same variable to all setters and a different variable to all getters, it gave me null value. WHY?
}
}
答案 0 :(得分:0)
您获得空值的原因是您没有为第二种情况设置这些变量的值。例如,让我们执行以下操作:
Encapsulationtom1 obj1 = new Encapsulationtom1();
Encapsulationtom1 obj2 = new Encapsulationtom1();
Encapsulationtom1 obj3 = new Encapsulationtom1();
obj1.setDesignation("Lead Designer");
obj1.setEmployeeId(23452);
obj1.setEmployeeName("Meliodas");
System.out.println("The designation is "+ obj1.getDesignation());
System.out.println("The designation is "+ obj2.getEmployeeId());
System.out.println("The designation is "+ obj3.getEmployeeName());
这两行:
System.out.println("The designation is "+ obj2.getEmployeeId());
System.out.println("The designation is "+ obj3.getEmployeeName());
将返回Null
,因为您还没有给它们一个值。因此,obj2
和obj3
的变量尚未实例化,调用它们将返回null
。