字符串的处理 排序
编写一个截取字符串的函数，输入为一个字符串和字节数，输出为按字节截取的字符串。 但是要保证汉字不被截半个，如"我ABC"4，应该截为"我AB"，输入"我ABC汉
?
DEF"，6，应该输出为"我ABC"而不是"我ABC+汉的半个"。
package test;
class SplitString
{
String SplitStr;
int SplitByte;
public SplitString(String str,int bytes)
{
SplitStr=str;
SplitByte=bytes;
System.out.println("The String is:′"+SplitStr+"′;SplitBytes="+SplitByte);
}
public void SplitIt()
{
int loopCount;
loopCount=(SplitStr.length()%SplitByte==0)?(SplitStr.length()/SplitByte):(SplitStr.length()/SplitByte+1);
System.out.println("Will Split into "+loopCount);
?? for (int i=1;i<=loopCount ;i++ )
?? {
??? if (i==loopCount){
??? System.out.println(SplitStr.substring((i-1)*SplitByte,SplitStr.length()));
??? } else {
??? System.out.println(SplitStr.substring((i-1)*SplitByte,(i*SplitByte)));
??? }
?? }
}
public static void main(String[] args)
{
SplitString ss = new SplitString("test中dd文dsaf中男大3443n中国43中国人0ewldfls=103",4);
ss.SplitIt();
}
}
?
?
修改后的:
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
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<ii.length;i++){
???????????? ii[i] =Integer.parseInt(s[i]);
??????????? }???
??????? Arrays.sort(ii);????
??????? //asc???
??????? for(int i=0;i<ii.length;i++ ){
????????? System.out.println(ii[i]);???
???????? }
?????? //desc????
??????? for(int i=(s.length-1);i>=0;i--){
????????? System.out.println(ii[i]);????
?????? }????????????
??? }
}
2.编写一个截取字符串的函数，输入为一个字符串和字节数，输出为按字节截取的字符串。 但是要保证汉字不被截半个，如"我ABC"4，应该截为"我AB"，输入"我ABC汉DEF"，6，应该输出为"我ABC"而不是"我ABC+汉的半个"。
代码：
public static boolean isLetter(char c){
??? int k=0X80;
??? return c/k==0?true:false;??
???
??? }
???
??? public static int lengths(String strSrc){
??? if (strSrc==null){
??? ?? return 0;
??? }
??? int len=0;
??? char[] strChar=strSrc.toCharArray();
??? for (int i=0;i<strChar.length;i++){
??? ?? len++;
??? ?? if (!isLetter(strChar[i])) len++;??? ??
??? }
??? return len;???
??? }
???
??? public static String subString(String origin,int len){
??? if (origin==null || origin.equals("")|| len<1){
??? ?? return "";
??? }
??? if (len>lengths(origin)){
??? ?? return origin;??? ??
??? }
??? byte[] strByte=new byte[len];
??? System.arraycopy(origin.getBytes(),0,strByte,0,len);
??? int count=0;
??? for (int i=0;i<len;i++){
??? ?? int value=(int)strByte[i];
??? ?? if (value<0) count++;??
??? }
??? if (count % 2 !=0){
??? ?? len=(len==1)?++len:--len;
??? }
??? return new String(strByte,0,len);
???
??? }???
public static void main(String[] args) {
??????????? System.out.println(""+ subString("我ABC汉DEF",6));
??
}
3、排序都有哪几种方法？请列举。用JAVA实现一个快速排序。?????
排序的方法有：插入排序（直接插入排序、希尔排序），交换排序（冒泡排序、快速排序），选择排序（直接选择排序、堆排序），归并排序，分配排序（箱排序、基数排序）
快速排序的伪代码。
/ /使用快速排序方法对a[ 0 :n- 1 ]排序从a[ 0 :n- 1 ]中选择一个元素作为m I d d l e，该元素为支点把余下的元素分割为两段left 和r I g h t，使得l e f t中的元素都小于等于支点，而right 中的元素都大于等于支点递归地使用快速排序方法对left 进行排序递归地使用快速排序方法对right 进行排序所得结果为l e f t + m I d d l e + r I g h t
//以下为java程序实现的快速排序算法：
public static void sort(int[] data) {
??????? quickSort(data,0,data.length-1);
}
public static void quickSort(int[] data,int low,int high){
???? int pivotIndex=(low+high)/2;
????? swap(data,pivotIndex,high);???
???? int k=partition(data,low-1,high,data[high]);????
?????? swap(data,k,high);
???? if ((k-low)>1) partition(data,low,k-1);
???? if ((high-k)>1) partition(data,k+1,high);
?
}
public static int partition(int[] data int low,int high, int pivot ){
????? do {
???????????? while (data[++low]<pivot) ;
???????????? while (high!=0?? && data[--high]>pivot);
????????????? swap(data,low,high);
????? }
????? while (low<high) ;
????? swap(data,low,high);
????? return low;
}
public static void swap(int[] data int low,int high){
???? int tmp=data[low];
???? data[low]=data[high];
???? data[high]=tmp;
????
}
public static void main(String[] args){
?? int[] data = new int[]{89,32,425,32,78,1,53,92};
?? sort(data);
}
4.试用递归的方法写一下计算菲波那契数列的通项f(n),已知f1=1,f2=1,以后每项都是前两项的和。
..............
public static long fibonacci(long m){
if (m==0 || m==1) return m;
else return fibonacci(m-1)+fibonacci(m-2);
}
5. 写一个Singleton出来。
Singleton模式主要作用是保证在Java应用程序中，一个类Class只有一个实例存在。
一般Singleton模式通常有几种种形式:
第一种形式: 定义一个类，它的构造函数为private的，它有一个static的private的该类变量，在类初始化时实例话，通过一个public的getInstance方法获取对它的引用,继而调用其中的方法。
Public class Singleton {
??????????? private Singleton(){}
??????????? //在自己内部定义自己一个实例，是不是很奇怪？
???? //注意这是private 只供内部调用
???? private static Singleton instance = new Singleton();
???? //这里提供了一个供外部访问本class的静态方法，可以直接访问
???? public static Singleton getInstance() {
???? return instance;
???? }
}
???? 第二种形式:
public class Singleton {
private static Singleton instance = null;
public static synchronized Singleton getInstance() {
?? //这个方法比上面有所改进，不用每次都进行生成对象，只是第一次
?? //使用时生成实例，提高了效率！
???? if (instance==null)
?? instance＝new Singleton();
??????????? return instance;
??? }
}
其他形式:
定义一个类，它的构造函数为private的，所有方法为static的。
一般认为第一种形式要更加安全些
6、创建一个静态方法，给它传入一个对象，请循环的打印出该对象所在类的类名和所实现的方法名（华为笔试最后一道编程）???
import java.lang.reflect.*;
public class Test{
public static void test(Object obj){
???? Class clazz=obj.getClass();
???? //System.out.println("类名:"+clazz.getName());
???? Method[] ms=clazz.getDeclaredMethods();
???? long len=Array.getLength(ms);
???? for(int i=0;i<len;i++){
???????? System.out.println("类名:"+clazz.getName()+"方法名:"+ms[i].getName());
??? }?????
}
class A{
???? public void b(){}??????
???? public void c(){}??????
???? public void d(){}???????
???? public void e(){}
}
public static void main(String[] args){
????? Test t=new Test();
????? Test.A a=t.new A();
?????? test(a);
}
}?????
7、假设字符串类似这样的aba和aab就相等，现在随便给你二组字符串，请编程比较他们看是否相等??
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));??????
String s = null;
try {
s = br.readLine();
} catch (IOException e) {
e.printStackTrace();
}???????
StringTokenizer st = new StringTokenizer(s);
String s1 = st.nextToken();
String s2 = st.nextToken();???????
byte[] sa1 = s1.getBytes();
byte[] sb2 = s2.getBytes();
Arrays.sort(sa1);
Arrays.sort(sb2);???????
String ss1 = new String(sa1);
String ss2 = new String(sb2);???????
if(ss1.equals(ss2))
System.out.println("equal");
else
System.out.println("not equal");
8、给你一组字符串如：iu7i8hy4jnb2，让你编程输出里面的数字：7842???
??? 用正规表达式："iu7i8hy4jnb2".replaceAll("[^\\d]","");
9、给你一组字符串让你把它倒叙输出???
public static String flashBack(String origin) {
?? String result = "";
?? for (int i = origin.length(); i > 0; i--) {
??? String tmp = origin.substring(i - 1, i);
??? result += tmp;
?? }
?? return result;
}
10、给你一组字符如{1，3，4，7，2，1，1，5，2}，让你输出里面出现次数最多且数值最大的一个，出现几次??
public void fun4() {
??? int[] a = { 4, 1, 2, 4, 5, 1, 1, 1, 5, 1, 3, 4, 5 };
??? Arrays.sort(a);
??? for (int i = 0; i < a.length; i++) {
??????? System.out.print(a[i] + " ");
??? }
?? System.out.println();
?? int maxNumber = a[a.length - 1], maxCount = 1;
?? int curNumber = a[a.length - 1], curCount = 1;
?? for (int i = a.length - 1; i > 0; i--) {
??????? curNumber = a[i];
??????? if (a[i] == a[i - 1]) {
??????????? curCount++;
??????? } else {
???????????? System.out.println("i=" + i + ",curCount=" + curCount+ ",maxCount=" + maxCount + ",maxNumber=" + maxNumber);
???????????? if (curCount > maxCount) {
???????????????? maxCount = curCount;
???????????????? maxNumber = curNumber;
???????????? }
??????????? curCount = 1;
????????? }
}
?? if (curCount > maxCount) {
????? maxCount = curCount;
????? //maxNumber = curNumber;
}
System.out.println("curCount=" + curCount + ",maxCount=" + maxCount + ",maxNumber=" + maxNumber);
}??
11、求两个数的公约数，M，N???
int divisor =1;
for (int i = 2; i <= b; i++) {
if(a%i==0 && b%i==0){
divisor = i;
}
}
System.out.println(a+"和"+b+"的最大公约数是:"+divisor);
}??
12、实现数组复制???
public void fun8(){
int[] a = {1,2,3,4,56,7,8};
int[] b = (int[])a.clone();
Conica.print(a);
Conica.print(b);
b[0]=100;
Conica.print(a);
Conica.print(b);
}??
13、冒泡排序的实现???
public void fun9(){
int[] a = {1,5,2,6,8,74,1,25,69,8};
Conica.print(a);
for(int i=0; i<a.length-1; i++){
for(int j=0; j<a.length-i-1;j++){
if(a[j]>a[j+1]){
int temp = a[j];
a[j] = a[j+1];
a[j+1] = temp;
}
}
}
Conica.print(a);
}??
14、编程显示某一文件目录下的文件名???
public void fun10(){
File file = new File("G:\\03月份");
if(file.exists()){
if(file.isDirectory()){
String[] files = file.list();
Conica.println(files);
}
}
}
15、从键盘输入4个十进制数字字符，将其转换为4位时间之数并显示出来
16、编程实现统计文本文件中某个单词的出现频率，并输出统计结果??
用HashMap来解决
假设单词不存在跨行的,每个单词用,. ;分割???????
public static void countNum() throws IOException {
?? BufferedReader br = null;
?? try {
??? br = new BufferedReader(new FileReader("c://file.txt"));
??? Map map = new HashMap();
??? for (String s = br.readLine(); s != null; s = br.readLine()) {
???? StringTokenizer st = new StringTokenizer(s, ",.?? ;");
???? while (st.hasMoreTokens()) {
????? String temp = st.nextToken();
????? if (map.containsKey(temp)) {
?????? map.put(temp, new Integer((Integer)map.get(temp) + 1));
????? } else {??????
?????? map.put(temp, new Integer(1));
????? }
???? }
??? }
??? for (Iterator it = map.entrySet().iterator(); it.hasNext();) {
???? Map.Entry entry = (Map.Entry) it.next();
???? System.out.println(entry.getKey() + "-->" + entry.getValue()
?????? + "times");
??? }
?? } finally {
??? br.close();
?? }
}
17、编程模仿DOS下的dir命令，列出某个目录下的内容
18、编程说明String和StringBuffer字符串的区别??
19、编程计算N!的程序，一个使用递归方法，一个不用递归方法???
递归 :
long fuction(int n){
?? if (n==0) return 1;
else??????
???? return n* fuction(n-1);???
}??
不递 :
long s=1;
for(int i=2;i<=n;i++)
{
????? s*=i;
}
20、编程实现ASCII码和Unicode码之间的转换??
21.用1、2、2、3、4、5这六个数字，用java写一个main函数，打印出所有不同的排列，如：512234、412345等，要求： "4 "不能在第三位， "3 "与 "5 "不能相连.
此题具体算法及程序可参考：
http://topic.csdn.net/u/20070114/14/1170e023-e8f0-4331-8bd8-516c6f1e40da.html
22。一个字符串中可能包含a~z中的多个字符，如有重复，如String data="aavzcadfdsfsdhshgWasdfasdf"，求出现次数最多的那个字母及次数，如有多个重复的则都求出。〔金山公司面试题〕
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.TreeSet;
public class FindRepeatChar {
public static void doString(String strInput) {
?? char[] chars = strInput.toCharArray();
?? ArrayList lists = new ArrayList();
?? TreeSet set = new TreeSet();
?? for (int i = 0; i < chars.length; i++) {
??? lists.add(String.valueOf(chars[i]));
??? set.add(String.valueOf(chars[i]));
?? }
?? System.out.println(set);
?? Collections.sort(lists);
?? System.out.println(lists);
?? StringBuffer sb = new StringBuffer();
?? for (int i = 0; i < lists.size(); i++) {
??? sb.append(lists.get(i));
?? }
?? strInput = sb.toString();
?? System.out.println(strInput);
?? int max = 0;
?? String maxString = "";
?? ArrayList maxList = new ArrayList();
?? for (Iterator its = set.iterator(); its.hasNext();) {
??? String os = (String) its.next();
??? int begin = strInput.indexOf(os);
??? int end = strInput.lastIndexOf(os);
??? int value = end - begin + 1;
??? if (value > max && value > 1) {
???? max = value;
???? maxString = os;
???? maxList.add(os);
??? } else if (value == max) {
???? maxList.add(os);
??? }
?? }
?? int index = 0;
?? for (int i = 0; i < maxList.size(); i++) {
??? if (maxList.get(i).equals(maxString)) {
???? index = i;
???? break;
??? }
?? }
?? System.out.println("出现最多的字符为：");
?? for (int i = 0; i < maxList.size(); i++) {
??? System.out.println(maxList.get(i) + "");
?? }
?? System.out.println();
?? System.out.println("出现最多的次数为：" + max);
}
public static void main(String[] args) {
?? String strInput = new String("aavzcadfdsfsdhshgWasdfasdf");
?? doString(strInput);
}
}
23．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。
package test.money;
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 synchronized 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++) {//123363
??? 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) {//inclusive. exclusive.
??? 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);
?? cMoneyStringBuffer.insert(cMoneyStringBuffer.length() - 1, JIAO);
?? cMoneyStringBuffer.insert(cMoneyStringBuffer.length(), FEN);
?? if (cMoneyStringBuffer.indexOf("零角零分") != -1)// 没有零头，加整
??? cMoneyStringBuffer.replace(cMoneyStringBuffer.indexOf("零角零分"),
????? cMoneyStringBuffer.length(), "整");
?? else if (cMoneyStringBuffer.indexOf("零分") != -1)// 没有零分，加整
??? cMoneyStringBuffer.replace(cMoneyStringBuffer.indexOf("零分"),
????? cMoneyStringBuffer.length(), "整");
?? else {
??? if (cMoneyStringBuffer.indexOf("零角") != -1)
???? cMoneyStringBuffer.delete(cMoneyStringBuffer.indexOf("零角"),
?????? cMoneyStringBuffer.indexOf("零角") + 2);
??? // tmpBuffer.append("整");
?? }
?? result = cMoneyStringBuffer.toString();
?? return result;
}
private void checkPrecision(String moneyStr) {//5336.53663?? 10-5-1
?? int fractionDigits = moneyStr.length() - moneyStr.indexOf(DOT) - 1;
?? if (fractionDigits > 2)
??? throw new RuntimeException("金额" + moneyStr + "的小数位多于两位。"); // 精度不能比分低
}
public static void main(String[] args) {??
??? System.out.println(getInstance().format(new Double(8951.11)));??
}
}
