java复习资料

1、阅读以下程序，输出结果为。

class Q1{public static void main（String args[ ]）{ double d=1.23;Dec dec=new Dec( );dec.decrement(d);System.out.println(d);}classs Dec{public void decrement(double decMe){decMe = decMe － 0.1;}}2、以下程序段的输出结果为。

class Cruncher{void crunch( int i ){System.out.println(“int version”);}void crunch(String s){System.out.println(“String version”);}public static void main(String args[ ]){Cruncher crun=new Cruncher ( );char ch=’p’;crun.crunch(ch); }}3、阅读以下程序段:class Parent{void printMe(){System.out.println(“pt”);}}class Child extends Parent{void printMe(){System.out.print (“cd”);}void printAll(){super.printMe();this.printMe();printMe();}}public class Test_this{public static void main(String args[ ]){Child myC=new Child();myC.printAll();}}输出结果为。

4、已有Bird类的定义如下：package abcde;public class Bird{protected static int referenceCount=0；public Bird（）{ referenceCount++； }protected void fly（）{ }static int getReCount（）{ return referenceCount； }}有类Nightingale的定义如下，请写出它的输出结果。

package singers；class Nightingale extends abcde.Bird{Nightingale( ){ referenceCount++;}public static void main( String args[ ]){System.out.print(“Before:”+referenceCount);Nightingale florence=new Nightingale( );System.out.println(“ After:”+referenceCount);florence.fly( );}}5、以下程序段的输出结果为。

public class test{public static void main(String args[ ]){StringBuffer s = new StringBuffer("Hello");s.append("there");System.out.println(s);String pf = s.substring(0, s.length());System.out.println(pf.equals("Hellothere"));}}6、以下程序段的输出结果为。

class Person{public Person(){System.out.println("hi!");}public Person(String s){this();System.out.println("I am "+s);}}public class Who extends Person{public Who(){this("I am Tony");}public Who(String s){super(s);System.out.println("How do you do?");}public static void main(String args[]){Who w = new Who("Tom");}}7．下面是一个类的定义。

class ____________ // 定义名为MyClass的类{__________ int var=666;static int getvar(){ return var;}}8．以下程序的输出结果为。

public class abc{public static void main(String args[ ]){ SubSubClass x = new SubSubClass(10 , 20 , 30); x.show();}}class SuperClass{ int a,b;SuperClass(int aa , int bb){ a=aa; b=bb; }void show( ){ System.out.println("a="+a+"\nb="+b); }}class SubClass extends SuperClass{ int c;SubClass(int aa,int bb,int cc){ super(aa,bb);c=cc;}}class SubSubClass extends SubClass{ int a;SubSubClass(int aa,int bb,int cc){ super(aa,bb,cc);a=aa+bb+cc;}void show(){ System.out.println("a="+a+"\nb="+b+"\nc="+c); } }9．以下程序的输出结果为。

class Person{public Person(){System.out.println("Person");}}class Student extends Person{publid Student(){System.out.println("Student");}}class CollegeStudent extends Student{public CollegeStudent(){System.out.println("CollegeStudent");}}public class Test{public static void main(String[] args){CollegeStudent cs=new CollegeStudent();}}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 Reverse{public static void main(String args[]){int i,n=10;int a[]=new int[10];for (i=0;i<n;i++)try{BufferedReader br=new BufferedReader( );a[i]=Integer.parseInt( ); //输入一个整数}catch(IOException e){};for(i=n-1;i>=0;i--)System.out.print(a[i]+" ");System.out.println();}}11．以下程序的输出结果为。

public class EqualOrNot{public static void main(String args[]){B b1=new B(5);B b2=new B(5);System.out.println(b1==b2);System.out.println(b1.equals(b2));}}class B{int x;B(int y){x=y;}}12．以下程序的输出结果为。

class Parent{void printMe(){System.out.println("parent");}}class Child extends Parent{void printMe(){System.out.println("child");}void printAll(){super.printMe();this.printMe();printMe();} b}public class Test_this{public static void main(String args[]){Child myC=new Child();myC.printAll();}}13．以下程序的输出结果为。

class Cruncher{void crunch( int i ){System.out.print(“int”);}void crunch(String s){System.out.print(“String”);}public static void main(String args[ ]){Cruncher crun=new Cruncher ( );char c h=’h’;int i=12;crun.crunch(ch);System.out.print(“,”);crun.crunch(i);}}14．阅读以下程序：import java.io.*;public class AboutFile{public static void main(String[ ] args){BufferedReader b=new BufferedReader (new InputStreamReader( System.in));String s;System.out.flush();try{ s=b.readLine();System.out.println(“String is:”+s);}Catch(IOException e){ System.out.println(e.getMessage());}}}运行以上程序，若从键盘输入：java<回车>则输出结果为。