java 面试编程题

前一段时间，面了大大小小n家公司，好多都有编程题，主要是看面试者的语言基本功，以及编程习惯。

package com.zhoubo;/** * 用迭代的方法，判断是不是一个回文字符串，如”abdba” * @author BZ70000910 * */public class AbcbA {public static void main(String [] args){AbcbA instance = new AbcbA();System.out.println(instance.isAbcbA("abcefg"));}public boolean isAbcbA(String str){while(str.length() > 1){int length = str.length();char first = str.charAt(0);char last = str.charAt(length - 1);if(first == last){String strcpy = str.substring(1, length - 1);System.out.println(strcpy);isAbcbA(strcpy);}else{return false;}//不加break,就会进入死循环,因为退出循环也是一层一层的。做改错题肯定有意思。break;}return true;}}

package com.zhoubo;/** *如何用java读取大文件 */import java.io.RandomAccessFile;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;public class ReadBigFile {/** * @param args */public static void main(String[] args)throws Exception {//定义缓冲区的大小为1KBint bufSize = 1024;byte [] bs = new byte[bufSize];ByteBuffer byteBuffer = ByteBuffer.allocate(bufSize);FileChannel channel = new RandomAccessFile("c://dmmsi.log","r").getChannel();int size;//读取到输入流的最后while((size = channel.read(byteBuffer))!=-1){byteBuffer.rewind();byteBuffer.get(bs);System.out.println(new String(bs, 0, size));byteBuffer.clear();}channel.close();}}

package com.zhoubo;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.nio.CharBuffer;/** * 读取字符串序列，如果有“abcd“，则返回true. * 提供一个每次读一个字符的函数 * public char getChar() * @author BZ70000910 * */public class SimenseTest {static CharBuffer temp = CharBuffer.allocate(1024);/** * @param args */public static void main(String[] args)throws IOException {String str = "ABCD";InputStreamReader isr = new InputStreamReader(System.in);BufferedReader br = new BufferedReader(isr);br.read(temp);SimenseTest st = new SimenseTest();System.out.println(st.findString(str));}public char getChar()throws IOException{temp.flip();char x = temp.get();temp.compact();return x;}public boolean findString(String str)throws IOException{char temp;int i = 0;while((temp = getChar())!=0){//System.out.println(temp);if(temp == str.charAt(i)){if(i == 3){return true;}elsei++;}elsei = 0;}return false;}}

package com.zhoubo;/** *编写一个class，提供void addElement(int element)方法， *提供int maxi()，提供int mini()，提供 int elementLength()，提供中间值int middle() */import java.util.ArrayList;import java.util.Arrays;public class SimenseTest2 {private ArrayList<Integer> arrayList;public SimenseTest2(ArrayList<Integer> arrayList) {this.arrayList = arrayList;}public void addElement(int element){arrayList.add(element);}public int maxi(){int max = arrayList.get(0) ;for(int i = 1; i < arrayList.size(); i++){if(max < arrayList.get(i))max = arrayList.get(i);}return max;}public int mini(){int mini = arrayList.get(0);for(int i = 1; i < arrayList.size(); i++){if(mini > arrayList.get(i))mini = arrayList.get(i);}return mini;}public int length(){return arrayList.size();}public int middle(){int middle = 0;int size = arrayList.size();Integer [] array = (Integer [])arrayList.toArray(new Integer[size]);Arrays.sort(array);return array[size/2];}/** * @param args */public static void main(String[] args) {ArrayList<Integer> arrayList = new ArrayList<Integer>();SimenseTest2 st2 = new SimenseTest2(arrayList);st2.addElement(2);st2.addElement(3);st2.addElement(4);st2.addElement(5);st2.addElement(6);System.out.println(st2.maxi());System.out.println(st2.mini());System.out.println(st2.middle());}}  

package com.zhoubo;/** *用stringtokenizer的方法，建立一个replace()方法 */import java.util.StringTokenizer;public class StringReplace {/** * @param args */public static void main(String[] args) {StringReplace sr = new StringReplace();System.out.println("orilly ooh heolloo".replace('o', 'e'));System.out.println(sr.CharReplace('o', 'e', "orilly ooh heolloo"));}public String CharReplace(char oldChar, char newChar, String str){StringTokenizer stk = new StringTokenizer(str, Character.toString(oldChar));System.out.println(stk.countTokens());StringBuffer temp = new StringBuffer();//判断替换字符是否在开头if(str.charAt(0) == oldChar)temp.append(newChar);while(stk.hasMoreElements()){temp.append(stk.nextToken());temp.append(newChar);}//判断替换字符是否在结尾if(!(str.charAt(str.length()-1) == oldChar))temp.deleteCharAt(temp.length()-1);//如果多个重复的被替换return temp.toString();}}

package com.zhoubo;/** *提供一个字符串，转化成10进制输出，例如“AA”,输出170 * @author BZ70000910 * */public class ZTETest {/** * @param args */public static void main(String[] args) {String str = "ABCDE" ;ZTETest test = new ZTETest();System.out.println(test.decimal(str));}public int decimal(String str){char [] chars;if(str != null){chars = str.toCharArray();}elsechars = null;int sum = 0;int j = 0;for(int i = str.length()-1; i>=0 ; i--){sum = sum + (getValue(chars[i])<<(4*j));j++;}return sum;}public int getValue(char x){switch(x){case '0': return 0;case '1': return 1;case '2': return 2;case '3': return 3;case '4': return 4;case '5': return 5;case '6': return 6;case '7': return 7;case '8': return 8;case '9': return 9;case 'A': return 10;case 'B': return 11;case 'C': return 12;case 'D': return 13;case 'E': return 14;case 'F': return 15;default: return 0 ;}}}

package com.zhoubo;/** * 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”。 * @author BZ70000910 * */public class ZTETest2 {/** * @param args */public static void main(String[] args) {String str = "我abc汉def";ZTETest2 test = new ZTETest2();System.out.println(str.substring(0,4));System.out.println(test.StringCutByByte(str, 2));}public String StringCutByByte(String str, int index){String temp = null;byte [] bytes = str.getBytes();byte [] bytetemp = new byte[index];for(int i=0; i<index ; i++ ){bytetemp[i] = bytes[i];System.out.println(bytes[i]);}if(index>1){if(bytes[index-1]<0&&bytes[index-2]>0){//第三个参数表示要解码的字节数temp = new String(bytetemp,0,index-1);}else{temp = new String(bytetemp);}}else{if(bytes[index-1]<0){temp = null;}elsetemp = new String(bytetemp,0,1);}return temp;}}