final

I was wondering if there was an equivalent to c++'s const in Java. I understand the final keyword, but unfortunately I cannot use that to declare a functions return value final. Instead, it always ensures the function cannot be overridden, correct? Basically, I want to make sure a given returned class cannot be modified and is read only. Is that possible in Java? Basically, I want to make sure a given returned class cannot be modified and is read only. Is that possible in Java? Not directly, but one workaround is an immutable object . Example - public final Foo{ private final String s; public

I am working with jshell of JDK9. I just created a final variable and assigned a value to it. And in the next line i just modified the value. And to my surprise, there was no error when modifying the final variables. Here is the code snippets: jshell> final int r = 0; | Warning: | Modifier 'final' not permitted in top-level declarations, ignored | final int r = 0; | ^---^ r ==> 0 jshell> r = 1; r ==> 1 jshell> System.out.println("r = "+r) r = 1 Is it what is expected from jshell? or there is some other way to work with final variables in jshell? While creating a final variable at the top-level

final和static关键字 （1）final关键字 final可以修饰成员变量，表示成员变量初始化后不可修改，变为常量。 final可以修饰方法，表示该方法不可被重写 final可以修饰类，表示该类不可以被继承 final可以修饰局部变量，表示该局部变量在初始化后，转变为常量。 （2）static关键字 static可以修饰成员变量、方法、代码块、内部类 static修饰的属性的初始化在编译时期（类加载的时候），初始化后可以修改（这点是与final的较大区别） static修饰的成员变量、方法在不创建类的对象时也可被访问，与类的具体对象无关 （3）static final static final修饰的属性表示一旦给值，就不可修改，并且可以通过类名访问 来源： https://blog.csdn.net/zys994612/article/details/100540920

Suppose I've a utility class which contains only static methods and variables. e.g: public abstract final class StringUtils { public static final String NEW_LINE = System.getProperty("line.separator"); public static boolean isNotNullOrSpace(final String string) { return !(string == null || string.length() < 1 || string.trim().length() < 1); } } In this scenario, it makes sense to make the class both abstract and final. Abstract because making an object of this class will be of no use as all methods are accessible statically. Final because the derived class cannot inherit anything from this

I have the following code: public class BookLib { void f() { final int x = 5; // Line 1 class MyCLass { void print() { System.out.println(x); } } } } I don't understand why should use final variable in this case (Line 1)? You've created an inner class here. Since the life-time of objects of this class can potentially be much greater than the runtime of the method invocation (i.e. the object can still exist long after the method has returned), it needs to "preserve" the state of local variables that it can access. This preserving is done by creating an (invisible, synthetic) copy inside the