JAVA面试编程题
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1．写一个函数，例如：给你的a b c则输出abc acb bac bca cab cba package test;import java.util.ArrayList;import java.util.List;public class ListOpreation{public static void main(String[]args){String s="ABCD";List<String>list=list(s,"");System.out.println(list.size());System.out.println(list);}public static List<String>list(String base,String buff){ List<String>result=new ArrayList<String>();if(base.length()<=0){result.add(buff);System.out.println(result.toString()+"&");}for(int i=0;i<base.length();i++){List<String>temp=list(new StringBuilder(base).deleteCharAt(i).toString(),buff+base.charAt(i));result.addAll(temp);}for(int i=0;i<base.length();i++){System.out.println(newStringBuilder(base).deleteCharAt(i).toString()+"=");System.out.println(base.charAt(i)+"*");System.out.println(buff+"#");}return result;}}执行结果：2．写一个函数，给你一个字符串倒序输出来。
package test;public class ListOperation{public static void main(String[]args){String str="aadsfdfgdfcvsdfsdf";strOperation(str);}private static void strOperation(String str){ //TODO Auto-generated method stubSystem.out.println("str:"+str);String newStr="";for(int i=0;i<str.length();i++){char c=str.charAt(str.length()-1-i);newStr=newStr+c;}System.out.println("newStr:"+newStr);}}执行结果：3．不使用中间变量把两个变量的值互换package test;public class ListOperation1{public static void main(String[]args){int a=20;int b=30;a=a*b;b=a/b;a=a/b;System.out.println("a="+a+'\n'+"b="+b);}}4．冒泡排序package test;public class ListOperation2{public static void main(String[]args){ int[]list={20,27,15,29,4,14,28};sort(list);for(int i=0;i<list.length;i++){System.out.print(list[i]+"");}System.out.println();}public static int[]sort(int[]list){ int temp;for(int i=0;i<list.length;i++){for(int j=i+1;j<list.length;j++){if(list[i]<=list[j]){temp=list[j];list[j]=list[i];list[i]=temp;}}}return list;}}执行结果：5．将一个文件复制到另一个文件中。
package test;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException; import java.io.FileOutputStream;import java.io.IOException;public class ListOperation3{public static void main(String[]args){File oldFile=new File("D:\\1.txt");File newFile=new File("D:\\2.txt");try{FileInputStream fis=new FileInputStream(oldFile);FileOutputStream fos=new FileOutputStream(newFile);int read=0;while((read=fis.read())!=-1){fos.write(read);fos.flush();}fos.close();fis.close();}catch(FileNotFoundException e1){//TODO Auto-generated catch blocke1.printStackTrace();}catch(IOException e){//TODO Auto-generated catch blocke.printStackTrace();}}}执行结果：6．将this is a test转化为This Is A Testpackage test;public class ListOperation4{public static void main(String[]args){String str=new String("this is a good person");char[]c=new char[str.length()];str.getChars(0,str.length(),c,0);if(c[0]>='a'&&c[0]<='z'){c[0]=(char)(c[0]-32);}for(int i=1;i<str.length();i++){if(c[i]==''){c[i+1]=(char)(c[i+1]-32);}}String str1=new String(c);System.out.println("Str1:"+str1);}}执行结果：7．题目：输入一行字符，分别统计出其中英文字母、空格、数字和其它字符的个数。
package test;import java.util.Scanner;public class ListOperation5{public static void main(String[]args){int countNum=0;int countWord=0;int countBlank=0;int countOther=0;Scanner in=new Scanner(System.in);System.out.println("请输入字符串：");String str=in.nextLine();char[]ch=str.toCharArray();for(int i=0;i<str.length();i++){if(ch[i]>='0'&&ch[i]<='9'){countNum++;}elseif((ch[i]>='a'&&ch[i]<='z')||(ch[i]>='A'&&ch[i]<='Z')){countWord++;}else if(ch[i]==''){countBlank++;}else{countOther++;}}System.out.println("字符串中数字的个数："+countNum+'\n'+"字符串中的字母的个数："+countWord+'\n'+"字符串中空格的个数："+countBlank+'\n'+"字符串中其他字符的个数："+countOther+'\n');}}执行结果：。
