问题: Given this method in a class: public String toString() { StringBuffer buffer = new StringBuffer(); buffer.append(‟<‟); buffer.append(this.name); buffer.append(‟>‟); return buffer.toString(); } Which is true?() A、 This code is NOT thread-safe.B、 The programmer can replace StringBuffer with StringBuilder with no other changes.C、 This code will perform well and converting the code to use StringBuilder will not enhance the performance.D、 This code will perform poorly. For better performance, the code should be rewritten: return “<“+ this.name + “>”;
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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: 现有: class TestA { public void start() { System.out.println("TestA"); } } public class TestB extends TestA { public void start() { System.out.println("TestB"); } public static void main (string[] args) ( ((TestA)new TestB()).start(); ) } 运行结果是哪项?() A、 TeStAB、 TeStBC、编译失败D、运行时抛出异常
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:Servlet A receives a request that it forwards to servlet B within another web application in the same web container. Servlet A needs to share data with servlet B and that data must not be visible to other servlets in A’s web application. In which object can the data that A shares with B be stored?()A、 HttpSessionB、 ServletConfigC、 ServletContextD、 HttpServletRequestE、 HttpServletResponse
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: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: A developer has created a special servlet that is responsible for generating XML content that is sent to adata warehousing subsystem. This subsystem uses HTTP to request these large data files, which are compressed by the servlet to save internal network bandwidth. The developer has received a request frommanagement to create several more of these data warehousing servlets. The developer is about to copyand paste the compression code into each new servlet. Which design pattern can consolidate thiscompression code to be used by all of the data warehousing servlets?()A、FacadeB、View HelperC、Transfer ObjectD、Intercepting FilterE、Composite Facade
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: 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: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:下列哪项是String的字面量?() A、“Hello”B、‘world’C、/u2345D、new String(“good”)
问题:下面哪些类可用于throw语句()A、ErrorB、ExceptionC、EventD、Throwable
问题:JDK由组成以下哪几部分组成?()A、 Java编程语言B、 工具及工具的APIC、 Java EE扩展APID、 Java平台虚拟机
问题:包访问级的成员能被哪些对象访问到() A、子类B、所有类C、同一个包中的其他类D、同一个包中的子类
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: public class Test { public static void main(String [] args) { int x =5; boolean b1 = true; boolean b2 = false; if((x==4) && !b2) System.out.print(”l “); System.out.print(”2 “); if ((b2 = true) && b1) System.out.print(”3 “); } } What is the result?() A、 2B、 3C、 1 2D、 2 3E、 1 2 3F、 Compilation fails.G、 Au exceptional is thrown at runtime.
问题: class Beverage { Beverage() { System.out.print("beverage "); } } class Beer extends Beverage { public static void main(String [] args) { Beer b = new Beer(14); } public int Beer(int x) { this(); System.out.print("beer1 "); } public Beer() { System.out.print("beer2 "); } } 结果是什么?() A、beer1 beverageB、beer2 beverageC、beverage beer1D、编译失败
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:什么是静态初始化器?它有什么特点?与构造方法有什么不同?