我的代码中想使用string数组去储存从文件中读取的字符串，我使用全局变量dictionary[]这个字符串数组在public String[] readFileByLines(String fileName, int firstWordLength)这个方法中复制tempString中的值，测试之后发现dictionary[]中可以得到所有的值。但是当我在 public boolean deCipher(String cipherTextInput, int[] keyInput,int firstWordLength,String[] dictionary)这个方法中再次测试dictionary[]中的值的时候，发现全部是空。我知道这可能存在只想地址，让后tempString被销毁，所以dictionary指向空的可能。但是我不明白怎样才能避免这种情况。 急求大家帮忙。代码贴在下面，谢谢了！大家主要帮忙看一下readFileByLines和deCipher这两个方法就好了。
public class VigAlgoCracker {
char[] inputTextChar;
char[] keyChar;
String[] dictionary;
final int wordIndex = 167964;
int realSize = 0;
//IdentityHashMap<String,String> map=new IdentityHashMap<String, String>();
public void setTextChar(String cipherTextInput) {
String temp = cipherTextInput.replaceAll(" ", "");
this.inputTextChar = temp.toCharArray();
if (this.inputTextChar.length == 0) {
System.out.println("The input is empty!");
return;
}
}
public boolean deCipher(String cipherTextInput, int[] keyInput,int firstWordLength) {
setTextChar(cipherTextInput);
int length1 = this.inputTextChar.length;
int[] cipherDigt = getDigit(length1, this.inputTextChar);
int[] plainDigt = getResultDigt(cipherDigt, keyInput);
for(int i=0;i<plainDigt.length;i++){
System.out.print(" "+plainDigt[i]);
}
System.out.println();
char[] charPlain=new char[plainDigt.length];
for(int i=0;i<plainDigt.length;i++){
charPlain[i]=(char)(plainDigt[i]+65);
System.out.print(charPlain[i]);
}
System.out.println();
String strPlain=new String(charPlain);
for(int i=0;i<dictionary.length;i++){
f(dictionary[i].equals(strPlain.substring(0,firstWordLength))){
System.out.print(strPlain);
return true;
}
System.out.println(dictionary[i]);
}
return false;
}
public int[] getDigit(int length, char[] textChar) {
int[] digit = new int[textChar.length];
for (int i = 0; i < length; i++) {
if ((int) textChar[i] < 91 && (int) textChar[i] > 64) {
digit[i] = (int) textChar[i] - 65;
} else if ((int) textChar[i] > 96 && (int) textChar[i] < 123) {
digit[i] = (int) textChar[i] - 97;
} else {
System.out.println("Your input is invalid,please enter letter only!");
return null;
}
}
return digit;
}
public int[] getResultDigt(int[] charDigt, int[] keyDigt) {
int length1 = charDigt.length;
int length2 = keyDigt.length;
int[] resultDigt = new int[charDigt.length];
int j = 0;
for (int i = 0; i < length1; i++) {
if (j < length2) {
resultDigt[i] = (charDigt[i] - keyDigt[j]) % 26;
if (resultDigt[i] < 0) {
resultDigt[i] = resultDigt[i] + 26;
}
} else {
j = 0;
resultDigt[i] = (charDigt[i] - keyDigt[j]) % 26;
if (resultDigt[i] < 0) {
resultDigt[i] = resultDigt[i] + 26;
}
}
j++;
}
return resultDigt;
}
public void getKeyWord(String cipherText, int keyLength,int firstWordLength,String[] dictionary) {
int[] key = new int[keyLength];
for (int i = 0; i < keyLength; i++) {
key[i] = 65;
}
int arrIndex = 0;
int alphLength = 0;
boolean test=false;
while (checkKey(key, keyLength)) {
while (alphLength < 26) {
key[0] = 65 + alphLength;
if(deCipher(cipherText, key,firstWordLength)==true){
return;
}
System.out.println();
alphLength++;
}
while (arrIndex < keyLength && key[arrIndex] == 90 && checkKey(key, keyLength)) {
key[arrIndex] = 65;
alphLength = 0;
arrIndex++;
}
if (arrIndex < keyLength) {
if (key[arrIndex] < 90) {
key[arrIndex]++;
arrIndex = 0;
}
}
}
}
public boolean checkKey(int[] key, int keyLength) {
for (int i = 0; i < keyLength; i++) {
if (key[i] != 90) {
return true;
}
}
return false;
}
public void readFileByLines(String fileName, int firstWordLength) {
File file = new File(fileName);
BufferedReader reader = null;
dictionary = new String[wordIndex];
try {
System.out.println("The files content show by lines:");
reader = new BufferedReader(new FileReader(file));
String tempString = null;
int index = 0;
while ((tempString = reader.readLine()) != null) {
if (tempString.length() == firstWordLength) {
this.dictionary[index] = new String(tempString);
System.out.println(this.dictionary[index]);
index++;
}
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e1) {
}
}
}
System.out.println();
return dictionary;
}
public static void main(String[] args) {
System.out.println("Please enter the file name or directory:");
Scanner input=new Scanner(System.in);
String fileName=input.nextLine();
//String fileName="dict.txt";
System.out.println("Please enter the ciphertext:");
String ciphertext= input.nextLine();
System.out.println("Please enter the first word length:");
int firstWordLength=input.nextInt();
System.out.println("Please enter the key length:");
int keyLength=input.nextInt();
VigAlgoCracker cracker=new VigAlgoCracker();
cracker.readFileByLines(fileName,firstWordLength);
cracker.getKeyWord(ciphertext,keyLength,firstWordLength);
}------解决思路----------------------
你发出来的代码有两个地方编译错误：
1、方法public void readFileByLines()中有return语句
2、215行cracker.getKeyWord(ciphertext,keyLength,firstWordLength);调用时的参数和方法定义不匹配
------解决思路----------------------
dictionary数组变量全局的跟函数内的冲突了，还有你定义dictionary数组167964这么长干嘛？如果文件数据少，这个数据里面读到的大部分都是null，这样你后面比较的时候总有null的数组成员会报空指针，业务逻辑要求这样吗？如果确实要求这样，把后面的equals改成strPlain.substring(0, firstWordLength).equals(dictionary[i])，让不为null的数据放equals前面
给你大致改了一下：
package JUnit;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class VigAlgoCracker {
char[] inputTextChar;
char[] keyChar;
String[] dictionary;
final int wordIndex = 167964;
int realSize = 0;
//IdentityHashMap<String,String> map=new IdentityHashMap<String, String>();
public void setTextChar(String cipherTextInput) {
String temp = cipherTextInput.replaceAll(" ", "");
this.inputTextChar = temp.toCharArray();
if (this.inputTextChar.length == 0) {
System.out.println("The input is empty!");
return;
}
}
public boolean deCipher(String cipherTextInput, int[] keyInput,
int firstWordLength) {
setTextChar(cipherTextInput);
int length1 = this.inputTextChar.length;
int[] cipherDigt = getDigit(length1, this.inputTextChar);
int[] plainDigt = getResultDigt(cipherDigt, keyInput);
for (int i = 0; i < plainDigt.length; i++) {
System.out.print(" " + plainDigt[i]);
}
System.out.println();
char[] charPlain = new char[plainDigt.length];
for (int i = 0; i < plainDigt.length; i++) {
charPlain[i] = (char)(plainDigt[i] + 65);
System.out.print(charPlain[i]);
}
System.out.println();
String strPlain = new String(charPlain);
for (int i = 0; i < dictionary.length; i++) {
if (strPlain.substring(0, firstWordLength).equals(dictionary[i])) {
System.out.print(strPlain);
return true;
}
System.out.println(dictionary[i]);
}
return false;
}
public int[] getDigit(int length, char[] textChar) {
int[] digit = new int[textChar.length];
for (int i = 0; i < length; i++) {
if ((int)textChar[i] < 91 && (int)textChar[i] > 64) {
digit[i] = (int)textChar[i] - 65;
} else if ((int)textChar[i] > 96 && (int)textChar[i] < 123) {
digit[i] = (int)textChar[i] - 97;
} else {
System.out.println("Your input is invalid,please enter letter only!");
return null;
}
}
return digit;
}
public int[] getResultDigt(int[] charDigt, int[] keyDigt) {
int length1 = charDigt.length;
int length2 = keyDigt.length;
int[] resultDigt = new int[charDigt.length];
int j = 0;
for (int i = 0; i < length1; i++) {
if (j < length2) {
resultDigt[i] = (charDigt[i] - keyDigt[j]) % 26;
if (resultDigt[i] < 0) {
resultDigt[i] = resultDigt[i] + 26;
}
} else {
j = 0;
resultDigt[i] = (charDigt[i] - keyDigt[j]) % 26;
if (resultDigt[i] < 0) {
resultDigt[i] = resultDigt[i] + 26;
}
}
j++;
}
return resultDigt;
}
public void getKeyWord(String cipherText, int keyLength,
int firstWordLength) {
int[] key = new int[keyLength];
for (int i = 0; i < keyLength; i++) {
key[i] = 65;
}
int arrIndex = 0;
int alphLength = 0;
boolean test = false;
while (checkKey(key, keyLength)) {
while (alphLength < 26) {
key[0] = 65 + alphLength;
if (deCipher(cipherText, key, firstWordLength) == true) {
return;
}
System.out.println();
alphLength++;
}
while (arrIndex < keyLength && key[arrIndex] == 90 &&
checkKey(key, keyLength)) {
key[arrIndex] = 65;
alphLength = 0;
arrIndex++;
}
if (arrIndex < keyLength) {
if (key[arrIndex] < 90) {
key[arrIndex]++;
arrIndex = 0;
}
}
}
}
public boolean checkKey(int[] key, int keyLength) {
for (int i = 0; i < keyLength; i++) {
if (key[i] != 90) {
return true;
}
}
return false;
}
public void readFileByLines(String fileName, int firstWordLength) {
File file = new File(fileName);
BufferedReader reader = null;
dictionary = new String[wordIndex];
try {
System.out.println("The files content show by lines:");
reader = new BufferedReader(new FileReader(file));
String tempString = null;
int index = 0;
while ((tempString = reader.readLine()) != null) {
if (tempString.length() == firstWordLength) {
this.dictionary[index] = new String(tempString);
System.out.println(this.dictionary[index]);
index++;
}
}
reader.close();
} catch (FileNotFoundException e) {
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e1) {
}
}
}
System.out.println();
}
public static void main(String[] args) {
System.out.println("Please enter the file name or directory:");
Scanner input = new Scanner(System.in);
String fileName = input.nextLine();
//String fileName="dict.txt";
System.out.println("Please enter the ciphertext:");
String ciphertext = input.nextLine();
System.out.println("Please enter the first word length:");
int firstWordLength = input.nextInt();
System.out.println("Please enter the key length:");
int keyLength = input.nextInt();
VigAlgoCracker cracker = new VigAlgoCracker();
cracker.readFileByLines(fileName, firstWordLength);
cracker.getKeyWord(ciphertext, keyLength, firstWordLength);
}
}