现有: class Pet implements Serializable { Collar c= new Collar(); } class Collar implements Serializable { collarPart cpl=new CollarPart ("handle"); CollarPart cp2=new CollarPart ("clip"); } class CollarPart implements Serializable() 如果Pet实例被序列化,则多少对象将被序列化?()
第1题:
下列哪个方法可用于创建一个可运行的类? ( )
A.public class X implements Runable {public void run(){...,.,}}
B.public class X implements Thread {public void run(){......}}
C.public class X implements Thread {public int run(){……}}
D.public class X implements Runable {protected void run(){.....}}
第2题:
在下面程序的下画线处应填入的选项是 public class Test______{ public static void main(String args[]) { Test t=new Test(); Thread tt=new Thread(t); tt.start(); } public void run() { for(int i=0;i<5;i++) System.out.println("i="+i); } }
A.implements Runnable
B.extends Thread
C.implements Thread
D.extends Runnable
第3题:
通过实现Rmmable接口创建线程,请在下面横线处填写代码完成此程序。
public class ThreadTest
{
public static void main(String args [])
{
Thread testObj1 = new Thread (new Hello ());
Thread testObj2 = new Thread (new Hello ());
testObj 2.start ( );
}
}
class Hello implements Runnable
{
int j;
public void run()
{
System.out.println("Hello" + j ++);
}
}
第4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;
第5题:
interface A{
int x = 0;
}
class B{
int x =1;
}
class C extends B implements A {
public void pX(){
System.out.println(x);
}
public static void main(String[] args) {
new C().pX();
}
}
错误。在编译时会发生错误(错误描述不同的JVM 有不同的信息,意思就是未明确的
x 调用,两个x 都匹配(就象在同时import java.util 和java.sql 两个包时直接声明Date 一样)。
对于父类的变量,可以用super.x 来明确,而接口的属性默认隐含为 public static final.所以可
以通过A.x 来明确。
第6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
第7题:
选择正确的语句填在下列程序的横线处,使程序正常运行。 package ch1; import java. io. *; import j ava. util. *; class C45 implements Seritizable ______Public Thread t = new Thread(new T45(), "t"); public intcnt = 0; public C45() { t. start ( ) class T45 implements Runnable public int[] a = new int[4]; public void run() { for(int i - 0; i < 4; i++) { a[i] - i +4; } } } public class ex45 { static String fileName = "ch1\\file45.txt"; public static void main(String[] args) throws Exception { C45 bj = new C45 (); FileOutputStream fos = new FileOutputStream(fileName); ObjectOutputStream os = new ObjectOutputStream(fos); oos. writeObject (obj); oos.clese (); fos.close (); System. out, println (obj . toString ( ) ); } }
A.transient
B.protected
C.package
D.final
第8题:
下列关于Test类的定义中,正确的是______。
A) class Test implements Runnabte{
public void run(){}
public void someMethod(){}
B) class Test implements Rnuuable{
public void run();
}
C) class Test implements Rnuuable{
public void someMethod();
}
D) class Test implements Rnuuable{
public void someMethod();{}
}
A.
B.
C.
D.
第9题:
下列关于Test类的定义中,正确的是( )。
A.class Test implements Runnable{ public void run{} Dublic void someMethod[]{} }
B.class Test implements Runnable( puIblic void run; }
C.class Test implements Runnable( Dublic void someMethod[]; }
D.class Test implements Runnable( public void someMethod{} }
第10题:
( 30 )在程序的下划线处应填入的选项是
public class Test _________{
public static void main(String args[]){
Test t = new Test();
Thread tt = new Thread(t);
tt.start();
}
public void run(){
for(int i=0;i<5;i++){
system.out.println( " i= " +i);
}
}
}
A ) implements Runnable
B ) extends Thread
C ) implements Thread
D ) extends Runnable