问题:Which two statements are true regarding the creation of a default constructor?() A、 The default constructor initializes method variables.B、 The compiler always creates a default constructor for every class.C、 The default constructor invokes the no-parameter constructor of the superclass.D、 The default constructor initializes the instance variables declared in the class.E、 When a class has only constructors with parameters, the compiler does not create a default constructor.
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问题: A developer is designing a multi-tier web application and discovers a need to hide the details of establishingand maintaining remote communications from the client. In addition, the application needs to find,in a transparent manner,the heterogeneous business components used to service the client’s requests. Which design patterns, working together, address these issues?()A、Business Delegate and Transfer ObjectB、Business Delegate and Service LocatorC、Front Controller and Business DelegateD、Intercepting Filter and Transfer Object
问题: 现有: -f是一个对java .io.File实例的合法引用 - fw足‘个对java.io.FileWriter实例的合法引用 - bw足一个对java.io.BufferedWriter实例的合法引用 以下哪一项无效?() A、PrintWriter prtWtr = new PrintWriter (f);B、PrintWriter prtWtr = new PrintWriter( fw);C、PrintWriter prtWtr = new PrintWriter(bw):D、BufferWriter bufWtr = new BufferedWritr(f);E、BufferWriter bufWtr = new BufferedWriter(fw);F、BufferWriter bufWtr = new BufferedWriter (bw):
问题:能够遍历泛型List〈Integer〉 al中的所有元素的语句是哪项?() A、for(Integer i : al)B、for(i : al)C、for(al)D、forEach(Integer i : al)
问题:以下有关接口的叙述错误的是哪项?() A、 一个类可以实现多个接口B、 接口不能被继承C、 类实现接口时必须实现其中的方法D、 接口中只能包含抽象方法和常量
问题: 现有: public class Tester { public static void main (String[] args) { intx-5; Integer xl=x; Integer x2=x; int x3=new Integer(5); system..ut.print(x1.equals(x)); system..ut.print(xl==x); system..ut.print(x2.equals(xl)); system..ut.print(x2==xl); system..ut.print(x2==x3); system..ut.print(x2.equals(x3)); } } 结果为:() A、编译失败B、falsefalsetruetruetruetrueC、truetruetruetruetruetrueD、falsefalsetruetruetruefalseE、truefalsetruefalsefalsetrueF、运行时异常被抛出
问题:关于抽象类与最终类,下列说法错误的是()。A、抽象类能被继承,最终类只能被实例化B、抽象类和最终类都可以被声明使用C、抽象类中可以没有抽象方法,最终类中可以没有最终方法D、抽象类和最终类被继承时,方法可以被子类覆盖
问题:以下描述正确的是()。A、CallableStatement是PreparedStatement的父接口B、PreparedStatement是CallableStatement的父接口C、CallableStatement是Statement的子接口D、PreparedStatement是Statement的父接口
问题:Swing JFrame类缺省的布局管理器是:() A、FlowLayoutB、GridLayoutC、BorderLayoutD、CardLayout
问题:下列哪项是String的字面量?() A、“Hello”B、‘world’C、/u2345D、new String(“good”)
问题:Which of the following statements about variables and their scopes are true? () A、 Instance variables are member variables of a class.B、 Instance variables are declared with the static keyword.C、 Local variables defined inside a method are created when the method is executed.D、 Local variables must be initialized before they are used.
问题:HTTP中的POST和GET在下列哪些方面有区别()。A、数据位置B、明文密文C、数据安全D、长度限度E、应用场景
问题: public class Base { public static final String FOO = “foo”; public static void main(String[] args) { Base b = new Base(); Sub s = new Sub(); System.out.print(Base.FOO); System.out.print(Sub.FOO); System.out.print(b.FOO); System.out.print(s.FOO); System.out.print(((Base)s).FOO); } } class Sub extends Base {public static final String FOO=bar;} What is the result?() A、 foofoofoofoofooB、 foobarfoobarbarC、 foobarfoofoofooD、 foobarfoobarfooE、 barbarbarbarbarF、 foofoofoobarbarG、 foofoofoobarfoo
问题:Which statements concerning the event model of the AWT are true?() A、At most one listener of each type can be registered with a component.B、Mouse motion listeners can be registered on a List instance.C、There exists a class named ContainerEvent in package java.awt.event.D、There exists a class named MouseMotionEvent in package java.awt.event.E、There exists a class named ActionAdapter in package java.awt.event.
问题:下列哪些访问修饰符是在子类中可见的?()A、 privateB、 defaultC、 protectedD、 public
问题:Java中方法绑定有哪些形式?()A、编译时刻绑定B、运行时刻绑定C、静态绑定D、私有绑定
问题: 现有: 1. class Book { 2. private final void read() { System.out.print("book "); } 3. } 4. class Page extends Book { 5. public static void main(String [] args) { 6. // insert code here 7. } 8. private final void read() { System.out.print("page "); } 9. } 和如下三个代码片段 ( x, y, z ): x. // just a comment y. new Page().read(); z. new Book().read(); 分别插入到第6行,有几个允许代码通过编译并可以运行且无异常?() A、 0B、 1C、 2D、 3
问题: 现有: class ThreadExcept implements Runnable { public void run() { throw new RuntimeException("exception "); } public static void main(String [] args) { new Thread(new ThreadExcept()).start(); try { int x = Integer.parseInt(args[0]); Thread.sleep(x); System.out.print("main "); } catch (Exception e) { } } } 和命令行: java ThreadExcept 1000 哪一个是结果?() A、 mainB、 编译失败C、 代码运行,但没有输出D、 main java.lang.RuntimeException: exception
问题:如果一个方法或变量是"private"访问级别,那么它的访问范围是:()。A、在当前类,或者子类中B、在当前类或者它的父类中C、在当前类,或者它所有的父类中D、在当前类中
问题:You need to store elements in a collection that guarantees that no duplicates are stored and all elements can be accessed in natural order. Which interface provides that capability?() A、Java.util.Map.B、Java.util.Set.C、Java.util.List.D、Java.util.StoredSet.E、Java.util.StoredMap.F、Java.util.Collection.