}
//7编写程序判断一个数是否为同构数据
public class Exam3 {
public static void main(String[] args) {
for(int i=10;i<=999;i++){
if ( i*i % 100==i || i*i*I 00==i ) }
System.out.println(i);
} }
//9编写程序练习将字符串转换为int、double类型，将数值类型转换为字符串类型。练习StringBuffer类的使用方法。 class StringExample
{ public static void main(String args[]) { String s1=new String(\ String s2=new String(\
int x =Integer.parseInr(s1); // 将s1转换为int类型
double y =Double.parseDouble(s2);; // 将s2转换为double类型
double z = x + y;
String s3 = new String(z); 或 String.valueOf(z);; //将z转换为字符串 StringBuffer StringBuffer(\
String s4 = new String(\
sbr.append(s4);; //将s4连接在sbr的
后面
System.out.println(sbr.toString()); //显示
为 Thingking in Java } }
二 、程序分析
sbr = new
1.写出下面程序的运行结果。 public class A{ private int x=50;
public void setX(int x){ this.x = x+50; }
public int getX(){ return x; } }
public class Tester {
public static void method1(A a){ a.setX(100); }
public static void method2(int x){ x = 50; }
public static void main(String[] args){ A a = new A(); method1(a);
System.out.println(a.getX()); int n = 10;
method2(n);
System.out.println(n); } }
2. 写出下面程序的运行结果。 import java.util.*; public class Ex2{
public static void main(String[] args){ Vector myList = new Vector(); myList.add(\ myList.add(\ myList.add(\ myList.set(2,\ myList.remove(0); myList.remove(0);
System.out.println(myList.get(0)); Hashtable ht = new Hashtable(); ht.put(\ ht.put(\
Iterator its = ht.values().iterator(); while(its.hasNext()){
System.out.println(its.next()); } } }
3. 写出下面程序的运行结果。 import java.util.*;
public class ArrayTester{
public static void main(String[] args){ int[] arrays1 = {1,3,5,7}; int[] arrays2 = {2,4,6,8}; int[] arrays3 = new int[4]; arrays2=arrays3;
for(int i=0;i
for(int i=0;i
}
4. 写出下面程序的运行结果。
class AAA
{ int add(int x,int y) { return x+y; } }
class BBB extends AAA { int add(int x,int y) { return x-y; } }
public class Exam8
{ public static void main(String args[]) { AAA a=new AAA();
System.out.println(a.add(66,44)); a=new BBB ();
System.out.println(a.add(66,44)); } }
5. 写出下面程序的运行结果。
public class Exam9 extends TT
{
public static void main(String args[]) {
Exam9 t=new Exam9 (\ }
public Exam9 (String s) {
super(s);
System.out.print(\ }
public Exam9 () {
this(\ } }
class TT {
public TT() {
System.out.print(\ }
public TT(String s) {
this();
System.out.print(\ } }
6. 写出下面程序的运行结果。
public class Exam10 {
String str=new String(\ char[] ch = {'a','b','c'};
public static void main(String args[]){ Exam10 ex = new Exam10(); ex.change(ex.str,ex.ch); System.out.println(ex.str+\ System.out.println(ex.ch); }
public void change(String str,char ch[]){ str = \ ch[0] = 'g'; } }
7. 指出下列程序运行的结果。 class Employee{
static void expenseAllowance(){
System.out.println(\}
class Manager extends Employee{ static void expenseAllowance(){
System.out.println(\}
class ex{
public static void main(String args[]){
Manager man = new Manager(); Employee emp1 = new Employee(); Employee emp2 = (Employee)man; man.expenseAllowance(); emp1.expenseAllowance();