access-modifiers

来源： https://stackoverflow.com/questions/32199989/what-are-the-differences-between-final-class-and-sealed-class-in-scala

来源： https://stackoverflow.com/questions/32199989/what-are-the-differences-between-final-class-and-sealed-class-in-scala

来源： https://stackoverflow.com/questions/32199989/what-are-the-differences-between-final-class-and-sealed-class-in-scala

问题 This question was asked from me in an interview. Can we declare private variables inside a public method? If can, can we access variables through the public method? I tried with java but it does not allow to define private variable inside a method why is that? public class GetUser { public String getUserName(){ private String user="David"; return user; }} 回答1: No, you can not. Variables inside method are considered local and can't have modifiers. You can have private fields in a class, but

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 2 years ago . Improve this question Obviously Java has a Access level package-private which achieved by not adding any explicit modifier. But isn't there a way to explicitly add this modifier? It's a bit confusing that we need to omit access level when we want to use member in package only

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 2 years ago . Improve this question Obviously Java has a Access level package-private which achieved by not adding any explicit modifier. But isn't there a way to explicitly add this modifier? It's a bit confusing that we need to omit access level when we want to use member in package only

问题 I am not able to understand why this code doesn't compile: class A { public static void main(String[] args) { System.out.println("hi"); } } private class B { int a; } I am saving the contents in a file named A.java - and I get an error: modifier private not allowed here // where I have defined class B This happens both when I try B as private and protected. Can someone please explain me the reason behind this? Thanks ! 回答1: From the Java Language specification: The access modifiers protected

问题 I am not able to understand why this code doesn't compile: class A { public static void main(String[] args) { System.out.println("hi"); } } private class B { int a; } I am saving the contents in a file named A.java - and I get an error: modifier private not allowed here // where I have defined class B This happens both when I try B as private and protected. Can someone please explain me the reason behind this? Thanks ! 回答1: From the Java Language specification: The access modifiers protected

问题 Can a package final variable be changed through reflection? Say I have this: public class Widget { final int val = 23; } Can the val be changed through reflection if made accessible? If so, is there any way to prevent it that without using the security manager? 回答1: Turns out, changing final members causes reflection-obtained values to differ from values returned by regular code! This is quite scary. import java.lang.reflect.Field; public class Test { private static final class Widget {

问题 Can a package final variable be changed through reflection? Say I have this: public class Widget { final int val = 23; } Can the val be changed through reflection if made accessible? If so, is there any way to prevent it that without using the security manager? 回答1: Turns out, changing final members causes reflection-obtained values to differ from values returned by regular code! This is quite scary. import java.lang.reflect.Field; public class Test { private static final class Widget {