41 . Can you extend an interface? 42 . Can a class extend multiple interfaces? 43 . What is an abstract class? 44 . When do you use an abstract class? 45 . How do you define an abstract method? 46 . Compare abstract class vs interface?
1.What is the return-type of the methods that implement the MouseListener interface? A. booleanB. BooleanC. voidD. Point 2.Select valid identifier of Java: A. %passwdB. 3d_gameC. $chargeD. this 3.Which declares an abstract method in an abstract Java class? A. public abstract method(...
1、具体方法(Concrete Method) 2、抽象方法(Abstract Method) 3、钩子方法(Hook Method) 工人的超类:Worker.java// 具体方法 public final void workOneDay() { Log.e("workOneDay", "---work start---"); enterCompany(); work(); exitCompany(); Log.e("workOneDay", "---work end---"); }...
public abstract void method(); C. public void abstract Method(};D. public abstract void method() {} 17.What happens when this method is called with an input of "Java rules"? 1. public String addOK(String S) { 2. S += " OK!"; 3. return S; 4. }...
Java Abstract Method A method that doesn't have its body is known as an abstract method. We use the same abstract keyword to create abstract methods. For example, abstract void display(); Here, display() is an abstract method. The body of display() is replaced by ;. If a class contai...
D)The program has a compile error because intValue is an abstract method in Number. E)The program compiles and runs fine. 该题本想现将Number对象x转换为子类,使用子类中才能使用的compareTo方法,但是这里是先使用访问操作符(.)在进行向子类型的转换,所以在没有完成转换的情况下,Number对象x没有...
63 What is a synchronized block? What is the difference between synchronized block and synchronized method? 64 Explain concurrent accumulators? And Concurrency in java? 65 Concurrent accumulators in java? 66 Difference between hot storage vs cold storage? 67 What is an abstract class in java? 68...
(d) implement all of the parent's abstract methods 2. Which of the following statements is (are) true about any abstract method in Java? I.It contains no definition. Ⅱ. It cannot be declared public. (a) I and II (b) I only (c) None (d) II only ...
4. What is the difference between an abstract class and an interface? - Abstract class: An abstract class is a class that cannot beinstantiated and is typically used as a base class for other classes. It can contain both abstract and non-abstract methods. Subclasses of an abstract class mus...
A class must be declaredabstractwhen it has one or more abstractmethods. A method is declared abstract when it has a method heading, but no body – which means that an abstract method hasno implementation codeinside curly braces like normal methods do. ...