二、Java编程与程序运行结果 1.Java编程,打印昨天的当前时刻public class YesterdayCurrent{
public void main(String[] args){
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1);
System.out.println(cal.getTime());
}
}
2.文件读写,实现一个计数器 public int getNum(){
int i = -1;
try{
String stri="";
BufferedReader in = new BufferedReader(new FileReader(f));
while((stri=in.readLine())!=null){
i = Integer.parseInt(stri.trim());
}
in.close();
}catch(Exception e){
e.printStackTrace();
}
return i;
}public void setNum(){
int i = getNum();
i++;
try{
PrintWriter out=new PrintWriter(new BufferedWriter(new FileWriter(f,false)));
out.write(String.valueOf(i)); //可能是编码的原因,如果直接写入int的话,将出现java编码和windows编码的混乱,因此此处写入的是String
out.close() ;
}catch(Exception e){
e.printStackTrace();
}
}
3. 指出下面程序的运行结果:class A{
static{
System.out.print("1");
}
public A(){
System.out.print("2");
}
}
class B extends A{
static{
System.out.print("a");
}
public B(){
System.out.print("b");
}
}
public class Hello{
public static void main(String[] ars){
A ab = new B(); //执行到此处,结果: 1a2b
ab = new B(); //执行到此处,结果: 1a2bab
}
}
注:类的static 代码段,可以看作是类首次加载(被虚拟机加载)执行的代码,而对于类的加载,首先要执行其基类的构造,再执行其本身的构造 4.写一个Singleton模式的例子public class Singleton{
private static Singleton single = new Singleton();
private Singleton(){}
public Singleton getInstance(){
return single;
}
}
public void main(String[] args){
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1);
System.out.println(cal.getTime());
}
}
2.文件读写,实现一个计数器 public int getNum(){
int i = -1;
try{
String stri="";
BufferedReader in = new BufferedReader(new FileReader(f));
while((stri=in.readLine())!=null){
i = Integer.parseInt(stri.trim());
}
in.close();
}catch(Exception e){
e.printStackTrace();
}
return i;
}public void setNum(){
int i = getNum();
i++;
try{
PrintWriter out=new PrintWriter(new BufferedWriter(new FileWriter(f,false)));
out.write(String.valueOf(i)); //可能是编码的原因,如果直接写入int的话,将出现java编码和windows编码的混乱,因此此处写入的是String
out.close() ;
}catch(Exception e){
e.printStackTrace();
}
}
3. 指出下面程序的运行结果:class A{
static{
System.out.print("1");
}
public A(){
System.out.print("2");
}
}
class B extends A{
static{
System.out.print("a");
}
public B(){
System.out.print("b");
}
}
public class Hello{
public static void main(String[] ars){
A ab = new B(); //执行到此处,结果: 1a2b
ab = new B(); //执行到此处,结果: 1a2bab
}
}
注:类的static 代码段,可以看作是类首次加载(被虚拟机加载)执行的代码,而对于类的加载,首先要执行其基类的构造,再执行其本身的构造 4.写一个Singleton模式的例子public class Singleton{
private static Singleton single = new Singleton();
private Singleton(){}
public Singleton getInstance(){
return single;
}
}
解决方案 »
- lucene全文检索案例java案例————0.2秒检索50万数据
- 求助
- 简单问题Log4j如何配置???log4j示例中好像乜嘢
- servlet是一个规范吗?
- spring Hibernate3 和struts2.0整合问题
- http://topic.csdn.net/u/20080729/10/823420cc-6a90-49b0-aa9c-c00542dba210.html?seed=185707771(相信CSDN上没人能解决)
- 创建了个关于XML的群希望大家加入讨论
- eclipse + myeclipse 开发hibernate问题(超难,超怪问题)
- 发送EMAIL的问题
- jolt+tuxedo...把我所有的分都给你啦!!!
- xml Schemade 的问题.建立连接的问题在哪里?
- html表单提交后 不用重新输入的方法
delete from tid
insert into tid select * from #tmpp
drop table #tmpp
如果有id主键(数字,自增1的那种),那么:(sql server2000下测试通过)delete from tableA where id not in
(select id = min(id) from tableA group by name)
2.delete from tablea & truncate table tablea的区别 truncate 语句执行速度快,占资源少,并且只记录页删除的日志;
delete 对每条记录的删除均需要记录日志
JAVA编程题
1.现在输入n个数字,以逗号,分开;然后可选择升或者降序排序;按提交键就在另一页面显示按什么排序,结果为,提供reset
显示被隐藏内容
import java.util.*;
public class bycomma{
public static String[] splitStringByComma(String source){
if(source==null||source.trim().equals(""))
return null;
StringTokenizer commaToker = new StringTokenizer(source,",");
String[] result = new String[commaToker.countTokens()];
int i=0;
while(commaToker.hasMoreTokens()){
result[i] = commaToker.nextToken();
i++;
}
return result;
}
public static void main(String args[]){
String[] s = splitStringByComma("5,8,7,4,3,9,1");
int[] ii = new int[s.length];
for(int i = 0;i<s.length;i++){
ii[i] =Integer.parseInt(s[i]);
}
Arrays.sort(ii);
//asc
for(int i=0;i<s.length;i++){
System.out.println(ii[i]);
}
//desc
for(int i=(s.length-1);i>=0;i--){
System.out.println(ii[i]);
}
}
}2.金额转换,阿拉伯数字的金额转换成中国传统的形式如:(¥1011)->(一千零一拾一元整)输出。
显示被隐藏内容
package test.format;
import java.text.NumberFormat;
import java.util.HashMap;
public class SimpleMoneyFormat {
public static final String EMPTY = "";
public static final String ZERO = "零";
public static final String ONE = "壹";
public static final String TWO = "贰";
public static final String THREE = "叁";
public static final String FOUR = "肆";
public static final String FIVE = "伍";
public static final String SIX = "陆";
public static final String SEVEN = "柒";
public static final String EIGHT = "捌";
public static final String NINE = "玖";
public static final String TEN = "拾";
public static final String HUNDRED = "佰";
public static final String THOUSAND = "仟";
public static final String TEN_THOUSAND = "万";
public static final String HUNDRED_MILLION = "亿";
public static final String YUAN = "元";
public static final String JIAO = "角";
public static final String FEN = "分";
public static final String DOT = "."; private static SimpleMoneyFormat formatter = null;
private HashMap chineseNumberMap = new HashMap();
private HashMap chineseMoneyPattern = new HashMap();
private NumberFormat numberFormat = NumberFormat.getInstance(); private SimpleMoneyFormat() {
numberFormat.setMaximumFractionDigits(4);
numberFormat.setMinimumFractionDigits(2);
numberFormat.setGroupingUsed(false); chineseNumberMap.put("0", ZERO);
chineseNumberMap.put("1", ONE);
chineseNumberMap.put("2", TWO);
chineseNumberMap.put("3", THREE);
chineseNumberMap.put("4", FOUR);
chineseNumberMap.put("5", FIVE);
chineseNumberMap.put("6", SIX);
chineseNumberMap.put("7", SEVEN);
chineseNumberMap.put("8", EIGHT);
chineseNumberMap.put("9", NINE);
chineseNumberMap.put(DOT, DOT); chineseMoneyPattern.put("1", TEN);
chineseMoneyPattern.put("2", HUNDRED);
chineseMoneyPattern.put("3", THOUSAND);
chineseMoneyPattern.put("4", TEN_THOUSAND);
chineseMoneyPattern.put("5", TEN);
chineseMoneyPattern.put("6", HUNDRED);
chineseMoneyPattern.put("7", THOUSAND);
chineseMoneyPattern.put("8", HUNDRED_MILLION);
} public static SimpleMoneyFormat getInstance() {
if (formatter == null)
formatter = new SimpleMoneyFormat();
return formatter;
} public String format(String moneyStr) {
checkPrecision(moneyStr);
String result;
result = convertToChineseNumber(moneyStr);
result = addUnitsToChineseMoneyString(result);
return result;
} public String format(double moneyDouble) {
return format(numberFormat.format(moneyDouble));
} public String format(int moneyInt) {
return format(numberFormat.format(moneyInt));
} public String format(long moneyLong) {
return format(numberFormat.format(moneyLong));
} public String format(Number moneyNum) {
return format(numberFormat.format(moneyNum));
} private String convertToChineseNumber(String moneyStr) {
String result;
StringBuffer cMoneyStringBuffer = new StringBuffer();
for (int i = 0; i < moneyStr.length(); i++) {
cMoneyStringBuffer.append(chineseNumberMap.get(moneyStr.substring(i, i + 1)));
}
//拾佰仟万亿等都是汉字里面才有的单位,加上它们
int indexOfDot = cMoneyStringBuffer.indexOf(DOT);
int moneyPatternCursor = 1;
for (int i = indexOfDot - 1; i > 0; i--) {
cMoneyStringBuffer.insert(i, chineseMoneyPattern.get(EMPTY + moneyPatternCursor));
moneyPatternCursor = moneyPatternCursor == 8 ? 1 : moneyPatternCursor + 1;
} String fractionPart = cMoneyStringBuffer.substring(cMoneyStringBuffer.indexOf("."));
cMoneyStringBuffer.delete(cMoneyStringBuffer.indexOf("."), cMoneyStringBuffer.length());
while (cMoneyStringBuffer.indexOf("零拾") != -1) {
cMoneyStringBuffer.replace(cMoneyStringBuffer.indexOf("零拾"), cMoneyStringBuffer.indexOf("零拾") + 2, ZERO);
}
while (cMoneyStringBuffer.indexOf("零佰") != -1) {
cMoneyStringBuffer.replace(cMoneyStringBuffer.indexOf("零佰"), cMoneyStringBuffer.indexOf("零佰") + 2, ZERO);
}
while (cMoneyStringBuffer.indexOf("零仟") != -1) {
cMoneyStringBuffer.replace(cMoneyStringBuffer.indexOf("零仟"), cMoneyStringBuffer.indexOf("零仟") + 2, ZERO);
}
while (cMoneyStringBuffer.indexOf("零万") != -1) {
cMoneyStringBuffer.replace(cMoneyStringBuffer.indexOf("零万"), cMoneyStringBuffer.indexOf("零万") + 2, TEN_THOUSAND);
}
while (cMoneyStringBuffer.indexOf("零亿") != -1) {
cMoneyStringBuffer.replace(cMoneyStringBuffer.indexOf("零亿"), cMoneyStringBuffer.indexOf("零亿") + 2, HUNDRED_MILLION);
}
while (cMoneyStringBuffer.indexOf("零零") != -1) {
cMoneyStringBuffer.replace(cMoneyStringBuffer.indexOf("零零"), cMoneyStringBuffer.indexOf("零零") + 2, ZERO);
}
if (cMoneyStringBuffer.lastIndexOf(ZERO) == cMoneyStringBuffer.length() - 1)
cMoneyStringBuffer.delete(cMoneyStringBuffer.length() - 1, cMoneyStringBuffer.length());
cMoneyStringBuffer.append(fractionPart); result = cMoneyStringBuffer.toString();
return result;
}
private String addUnitsToChineseMoneyString(String moneyStr) {
String result;
StringBuffer cMoneyStringBuffer = new StringBuffer(moneyStr);
int indexOfDot = cMoneyStringBuffer.indexOf(DOT);
cMoneyStringBuffer.replace(indexOfDot, indexOfDot + 1, YUAN);