java复习资料

1、1、阅读以下程序，输出结果为 。class Q1public static void main(String args ) double d=1.23;Dec dec =new Dec();dec.decreme nt(d);System.out.pri ntl n( d);classs Decpublic void decreme nt(double decMe) decMe = decMe 0.1;9 / 82、以下程序段的输出结果为class Crun chervoid crun ch( int i )System.out.pri ntl n(void crun ch(Stri ng s

2、)System.out.pri ntl n(public static void main(String args )Cruncherint version );String version ” );char ch= crun.crun ch(ch);crun=newP;Crun cher ();3、阅读以下程序段：class Pare ntvoid prin tMe()System.out.println(“pt ” );class Child exte nds Pare ntvoid prin tMe()System.out.print (“cd” );void prin tAll()su

3、per.pri ntMe();this.pri ntMe();prin tMe();public class Test_thispublic static void main(String args)Child myC=new Child();myC.pri ntAII();输出结果为 。4、已有Bird类的定义如下：package abcde;public class Birdprotected static int referen ceCo un t=0;public Bird() referen ceCo un t+; protected void fly() static int ge

4、tReCo unt() return referenceCount; 有类 Night in gale的定义如下，请写出它的输出结果 packagesin gers ;class Night in gale exte nds abcde.BirdNight in gale() referen ceCo un t+;public static void main( String args)System.out.print( “ Before: ” +referenceCount);Nighti ngale flore nce=new Nighti ngale();System.out.pri n

5、tl n(“ After:” +refere nceCo un t);flore nce.fly();5、 以下程序段的输出结果为 。public class testpublic static void main(String args)Strin gBuffer s = new Strin gBuffer(Hello);s.appe nd(there);System.out.pri ntl n( s);String pf = s.substring(0, s.length();System.out.pri ntln( pf.equals(Hellothere);6、 以下程序段的输出结果为

6、 。class Pers onpublic Pers on()System.out.pri ntl n(hi!);public Person( Stri ng s)this();System.out.println(I am +s);public class Who exte nds Personpublic Who()this(I am Tony);public Who(Stri ng s)super(s);System.out.println(How do you do?);public static void main(String args)Who w = new Who(Tom);7

7、. 下面是一个类的定义。class/ 定义名为 MyClass的类int var=666;static int getvar() retur n var;&以下程序的输出结果为 public class abcpublic static void main(String args) SubSubClass x = new SubSubClass(10,20,30);x.show();class SuperClass int a,b;SuperClass(i nt aa , int bb) a=aa; b=bb; void show() System.out.pri ntln (a=+a+nb=

8、+b); class SubClass exte nds SuperClass int c;SubClass(i nt aa,i nt bb,i nt cc) super(aa,bb);c=cc;class SubSubClass exte nds SubClass int a;SubSubClass(i nt aa,i nt bb,i nt cc) super(aa,bb,cc);a=aa+bb+cc;void show() System.out.pri ntln( a=+a+inb=+b+nc=+c); 9.以下程序的输出结果为 class Pers onpublic Person。Sys

9、tem.out.pri ntln (Pers on);class Stude nt exte nds Personpublid Stude nt()System.out.pri ntl n( Stude nt);class CollegeStude nt exte nds Stude ntpublic CollegeStude nt()System.out.pri ntln (CollegeStude nt);public class Testpublic static void main( Stri ng args)CollegeStude nt cs=new CollegeStude nt

10、();10 .通过键盘输入10个整数，并按输入的倒序输出这10个整数。import java.io.*;public class Reversepublic static void main(String args)int i,n=10;int a=new int10;for (i=0;i=0;i-)System.out.pri nt( ai+);System.out.pri ntl n();11.以下程序的输出结果为 。public class EqualOrNotpublic static void main(String args)B b1= new B(5);B b2=new B(5)

11、;System.out.pri ntln( b1=b2);System.out.pri ntln( b1.equals(b2);class Bint x;B(i nt y)x=y;12 以下程序的输出结果为 class Pare ntvoid prin tMe()System.out.pri ntl n(pare nt);class Child exte nds Pare ntvoid prin tMe()System.out.pri ntln (child);void prin tAll()super.pri ntMe();this.pri ntMe();prin tMe(); bpubli

12、c class Test_thispublic static void main(String args)Child myC=new Child();myC.pri ntAll();13 以下程序的输出结果为 classCrun chervoidcrun ch(int i )System.out.print( “int ” );voidcrun ch(Stri ngs)System.out.print( “String ” );args)public static voidmain( Stri ngCrun cher crun=newCrun cher();charch= h；inti=12;

13、crun.crun ch(ch);System.out.print( “, ” );crun.crun ch(i);14 阅读以下程序：import java.io.*;public class AboutFilepublic static voidmain( Stri ng args)BufferedReader b=new BufferedReader (new InputStreamReader(System.i n);Stri ng s;System.out.flush();try s=b.readL in e();System.out.println(“String is: ” +s

14、);Catch(IOException e) System.out.pri ntln( e.getMessage();publicclassTryCatchFi nallystaticvoid Proc( inttryif(sel=0System.out.pri ntl n( noreturn;else if(运行以上程序，若从键盘输入：java回车贝y输出结果为15 写出以下程序的运行结果。sel )Excepti on ”);sel=1 ) int i=0; int j=4/i;catch(ArithmeticExceptio nSystem.out.pri ntln (Catch cat

15、ch(Excepti onSystem.out.pri ntln (Will fin allySystem.out.pri ntl n(fin ally);static void mai n(Stri ngProc( 0);”);)notbeexecuted);public输出结果为： 15 阅读以下程序，写出输出结果。argsProc( 1);class An imalAn imal() System.out.pri nt(A nimal );public class Dogexte ndsAni malDog()System.out.pri nt(Dog );public static voidmain( Stri ngargs)Dogsn oppy=new Dog(); 输出结果为： 。编程题1、 编写一个类，要求该类实现一个接口，该接口有3个abstract方法：public abstract void f(int x);public abstract void g(i nt x, int y);public abstract double h