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更多“设有代码如下: class FrameInout extends Frame. implements ActionListener { Butto。() 此题为判断题(对,错)。”相关问题
  • 第1题:

    现有两个类A,B,以下描述中表示B继承自A的是 ( )

    A.class A extends B

    B.class B implements A

    C.class A implements B

    D.class B extends A


    正确答案:D
    解析:implements是实现接口时用到的关键字,不是继承的关键字。exteends是继承用到的关键字,而它表示的意思是前者继承后者,比如选项A中的class A extends B它表示的是A继承B,选项D表示的才是B继承自A。所以本题选择D。

  • 第2题:

    如果有一个类MyFrame是Frame的子类,但它不能被实例化,请写出该类的声明头为( )。

    A.abstract class Frame. extends MyFrame

    B.abstract class MyFrame. extends Frame

    C.class MyFrame. abstract extends Frame

    D.class Frame. abstract extends MyFrame.


    正确答案:B
    B【解析】本题考查考生对类声明的理解。类声明的格式为:[修饰符]class类名[extends父类名][implements类实现的接口列表],其中口括起来的内容为可选项。关键字class是类定义的开始,类名应符合标识符命名规则。关键字extends指明该类是子类,它的父类名紧跟其后,子类与父类之间有继承关系。关键字implements指明该类实现的接口,后跟接口名列表。考生应注意掌握类声明的概念,虽然很简单,但容易漏掉有关修饰符。题目要求声明不能被实例化的类,因此应该是一个抽象类,用abstract作为修饰符。

  • 第3题:

    设有程序如下: public class jzh0319 { public static void main(String args[]) { subClass sc=new subClass(); } } class superClass { superClass() { System.out.println("父类");} } class subClass extends superClass { subClass() {System.out.println("子类"); } } 其输出结果只有一行。()

    此题为判断题(对,错)。


    答案:错

  • 第4题:

    以下语句能顺利通过编译: final class class1 { } class class2 extends class1 { } 。()

    此题为判断题(对,错)。


    答案:错

  • 第5题:

    在J2EE中,对于自己编写的Servlet1,以下对Servlet1的定义正确的是()。    

    • A、class Servlet1 implements javax.servlet.Servlet
    • B、class Servlet1 extends javax.servlet.GenericServlet
    • C、class Servlet1 extends javax.servlet.http.HttpServlet
    • D、class Servlet1 extends javax.servlet.ServletRequest

    正确答案:A,B,C

  • 第6题:

    现在有两个类A、B,以下描述中表示B继承自A的是()

    • A、class A extends B
    • B、class B implements A
    • C、class A implements
    • D、class B extends A

    正确答案:D

  • 第7题:

    下列类的定义中,错误的是()。

    • A、class x{....}
    • B、public x extends y{....}
    • C、public class x extends y{....}
    • D、class x extends y implements y1{....}

    正确答案:B

  • 第8题:

    现有:  interface Animal {       void eat () ;       }       //insert code here       public class HouseCat extends Feline {       public void eat() { }       }  和五个申明  abstract class Feline implements Animal { }  abstract  class  Feline  implements  Animal  {  void eat () ;  }  abstract class Feline implements Animal { public void eat();}  abstract class Feline implements Animal { public void eat() {}  }  abstract class Feline implements Animal { abstract public void eat();} 结果为:()      

    • A、1
    • B、2
    • C、3
    • D、4

    正确答案:C

  • 第9题:

    Which two demonstrate an “is a” relationship?()   

    • A、 public interface Person { }  public class Employee extends Person { }
    • B、 public interface Shape { }  public class Employee extends Shape { }
    • C、 public interface Color { }  public class Employee extends Color { }
    • D、 public class Species { }  public class Animal (private Species species;)
    • E、 interface Component { }  Class Container implements Component ( Private Component[ ] children;  )

    正确答案:D,E

  • 第10题:

    多选题
    Which two demonstrate an “is a” relationship?()
    A

    public interface Person { }  public class Employee extends Person { }

    B

    public interface Shape { }  public class Employee extends Shape { }

    C

    public interface Color { }  public class Employee extends Color { }

    D

    public class Species { }  public class Animal (private Species species;)

    E

    interface Component { }  Class Container implements Component ( Private Component[ ] children;  )


    正确答案: E,B
    解析: 暂无解析

  • 第11题:

    单选题
    下列类的定义中,错误的是()。
    A

    class x{....}

    B

    public x extends y{....}

    C

    public class x extends y{....}

    D

    class x extends y implements y1{....}


    正确答案: D
    解析: 暂无解析

  • 第12题:

    单选题
    interface Data { public void load(); }  abstract class Info { public abstract void load(); }  Which class correctly uses the Data interface and Info class?()
    A

     public class Employee extends Info implements Data { public void load() { /*do something*/ } }

    B

     public class Employee implements Info extends Data { public void load() { /*do something*/ } }

    C

     public class Employee extends Info implements Data { public void load() { /*do something */ } public void Info.load() { /*do something*/ } }

    D

     public class Employee implements Info extends Data { public void Data.load() { /*dsomething */ } public void load() { /*do something */ } }

    E

     public class Employee implements Info extends Data { public void load() { /*do something */ } public void Info.load(){ /*do something*/ } }

    F

     public class Employee extends Info implements Data{ public void Data.load() { /*do something*/ } public void Info.load() { /*do something*/ } }


    正确答案: B
    解析: 暂无解析

  • 第13题:

    下列程序实现了2个监听器接口:ActionListener和W1ndowListener。 import java.awt.*; import java.awt.event.*; public class ex39______ { public static void main(String[] args) { ex39 bj = new ex39(); obj .go(); } public void go() { Frame. f = new Frame("ex39"); f.addWindowListener(this); Button b = new Button("Button"); b.addActionListener(this); f.add(b); f.pack(); f.setVisible(true); } public void actionPerformed(ActionEvent e) { System.out.println("Button pressed!"); } public void windowActivated(WindowEvent e){} public void windowDeactivated(WindowEvent e){} public void windowClosed(WindowEvent e) {} public void windowClosing(WindowEvent e){System.exit(1); public void windowIconified(WindowEvent e){} public void windowDeiconified(WindowEvent e) {} public void windowOpened(WindowEvent e){} } 请选择正确的语句填入横线处。

    A.extends ActionListener, WindowListener

    B.implements ActionListener, WindowListener

    C.implements ActionListener; WindowListener

    D.extends ActionListener; WindowListener


    正确答案:B

  • 第14题:

    设有如下代码:

    interface IFace{}

    class CFace implements IFace{}

    class Base{}

    public class ObRef extends Base{

    public static void main(String argv[]){

    ObRef bj = new ObRef();

    Base b = new Base();

    Object obj1 = new Object();

    IFace obj2 = new CFace();

    //Here

    }

    }

    则在 //Here处插入哪个代码将不出现编译和运行错误。

    A.obj1=obj2;

    B.b=obj;

    C.obj=b;

    D.obj1=b;


    正确答案:ABD

  • 第15题:

    设有程序如下: public class jzh0319 { public static void main(String args[]) { subClass sc=new subClass(); } } class superClass { superClass() { System.out.println("父类");} } class subClass extends superClass { subClass() {System.out.println("子类"); } } 其输出结果的第一行是子类。()

    此题为判断题(对,错)。


    答案:错

  • 第16题:

    设有程序如下: abstract class absclass { abstract void method1(); } class conclass extends absclass { public void method1() { System.out.println("子类");} } public class mainclass { public static void main(String args[]) { absclass ac1=new absclass(); //语句1 absclass ac2=new conclass(); //语句2 ac2.method1(); //语句3 } } 则main()方法中的第一条语句(即语句1)可以顺利通过编译。()

    此题为判断题(对,错)。


    答案:错

  • 第17题:

    interface Data { public void load(); }  abstract class Info { public abstract void load(); }  Which class correctly uses the Data interface and Info class?() 

    • A、 public class Employee extends Info implements Data { public void load() { /*do something*/ } }
    • B、 public class Employee implements Info extends Data { public void load() { /*do something*/ } }
    • C、 public class Employee extends Info implements Data { public void load() { /*do something */ } public void Info.load() { /*do something*/ } }
    • D、 public class Employee implements Info extends Data { public void Data.load() { /*dsomething */ } public void load() { /*do something */ } }
    • E、 public class Employee implements Info extends Data { public void load() { /*do something */ } public void Info.load(){ /*do something*/ } }
    • F、 public class Employee extends Info implements Data{ public void Data.load() { /*do something*/ } public void Info.load() { /*do something*/ } }

    正确答案:A

  • 第18题:

    现自:  1.  interface Color {  }      2. interface Weight  {  }      3.  //insert code here    和以下足六个声明:  class Boat extends Color, extends Weight  {  }     class Boat extends Color and Weight  {  }      class Boat extends Color, Weight  {  }  class Boat implements Color,  implements Weight  {  }     class Boat implements Color and Weight  {  }      class Boat implements Color, Weight  {  }    分别插入到第3行,有多少行可以编译? () 

    • A、  0
    • B、  1
    • C、  2
    • D、  3

    正确答案:B

  • 第19题:

    下列代码正确的是哪项?() 

    • A、 public class Session implements Runnable, Clonable{   public void run ();public Object clone () ; }
    • B、 public class Session extends Runnable, Cloneable {  public void run() {/*dosomething*/}       public Object clone() {/*make a copy*/} }
    • C、 public abstract class Session implements Runnable, Clonable {       public void run() {/*do something*/}       public Object clone() {/*make a copy*/}        }
    • D、 public class Session implements Runnable, implements Clonable {       public void run() {/*do something*/}       public Object clone() {/*make a copy*/}       }

    正确答案:C

  • 第20题:

    现有:  interface Data {public void load();}  abstract class Info {public abstract void load();}      下列类定义中正确使用Data和Info的是哪项?() 

    • A、 public class Employee implements Info extends Data { public void load(){/*dosomething*/}     }
    • B、public class Employee extends Inf.implements Data{ public void load() {/*do something*/}     }
    • C、public class Empl.yee implements Inf extends Data{ public void Data.1oad(){* do something*/}     public void load(){/*do something*/}     }
    • D、public class Employee extends Inf implements Data  {  public void Data.1oad()  {/*do something*/)     public void info.1oad(){/*do something*/}    }

    正确答案:B

  • 第21题:

    public abstract class Shape {  private int x;  private int y;  public abstract void draw();  public void setAnchor(int x, int y) {  this.x = x;  this.y = y;  }  }  Which two classes use the Shape class correctly?()

    • A、 public class Circle implements Shape { private int radius; }
    • B、 public abstract class Circle extends Shape { private int radius; }
    • C、 public class Circle extends Shape { private int radius; public void draw(); }
    • D、 public abstract class Circle implements Shape { private int radius; public void draw(); }
    • E、 public class Circle extends Shape { private int radius;public void draw() {/* code here */} }
    • F、 public abstract class Circle implements Shape { private int radius;public void draw() { / code here */ } }

    正确答案:B,E

  • 第22题:

    单选题
    下列代码正确的是哪项?()
    A

     public class Session implements Runnable, Clonable{   public void run ();public Object clone () ; }

    B

     public class Session extends Runnable, Cloneable {  public void run() {/*dosomething*/}       public Object clone() {/*make a copy*/} }

    C

     public abstract class Session implements Runnable, Clonable {       public void run() {/*do something*/}       public Object clone() {/*make a copy*/}        }

    D

     public class Session implements Runnable, implements Clonable {       public void run() {/*do something*/}       public Object clone() {/*make a copy*/}       }


    正确答案: A
    解析: 暂无解析

  • 第23题:

    单选题
    现自:  1.  interface Color {  }      2. interface Weight  {  }      3.  //insert code here    和以下足六个声明:  class Boat extends Color, extends Weight  {  }     class Boat extends Color and Weight  {  }      class Boat extends Color, Weight  {  }  class Boat implements Color,  implements Weight  {  }     class Boat implements Color and Weight  {  }      class Boat implements Color, Weight  {  }    分别插入到第3行,有多少行可以编译? ()
    A

      0

    B

      1

    C

      2

    D

      3


    正确答案: A
    解析: 暂无解析