Question

我的主类中有一个私有变量，是否可以在不将其设为受保护变量的情况下在其他类中使用它？

Answer 1

不。这就是private与protected的重点。 the Oracle Java member access tutorial中的详细信息，该功能还具有以下表格：

+−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+
|                  **Access Levels**                 |
+−−−−−−−−−−−−−−−+−−−−−−−+−−−−−−−−−+−−−−−−−−−−+−−−−−−−+
| Modifier      | Class | Package | Subclass | World |
+−−−−−−−−−−−−−−−+−−−−−−−+−−−−−−−−−+−−−−−−−−−−+−−−−−−−+
| public        |   Y   |    Y    |    Y     |   Y   |
| protected     |   Y   |    Y    |    Y     |   N   |
| (no modifier) |   Y   |    Y    |    N     |   N   |
| private       |   Y   |    N    |    N     |   N   |
+−−−−−−−−−−−−−−−+−−−−−−−+−−−−−−−−−+−−−−−−−−−−+−−−−−−−+

Answer 2

私有成员变量仅限于该类，但是您可以引入setter和getter方法来访问它们。这是encapsulation的一部分。

从上面的URL（教程点）中获得一个示例，我们有3个私有值，分别具有setter和getter方法，可根据需要检索或设置该值：

/* File name : EncapTest.java */
public class EncapTest {
   private String name;
   private String idNum;
   private int age;

   public int getAge() {
      return age;
   }

   public String getName() {
      return name;
   }

   public String getIdNum() {
      return idNum;
   }

   public void setAge( int newAge) {
      age = newAge;
   }

   public void setName(String newName) {
      name = newName;
   }

   public void setIdNum( String newId) {
      idNum = newId;
   }
}

您如何在子类中使用私有变量？

2 个答案: