CareerCup

public static String replaceOld(final String aInput, final String aOldPattern, final String aNewPattern) {
if (aOldPattern.equals("")) {
throw new IllegalArgumentException("Old pattern must have content.");
}

final StringBuffer result = new StringBuffer();
// startIdx and idxOld delimit various chunks of aInput; these
// chunks always end where aOldPattern begins
int startIdx = 0;
int idxOld = 0;
while ((idxOld = aInput.indexOf(aOldPattern, startIdx)) >= 0) {
// grab a part of aInput which does not include aOldPattern
result.append(aInput.substring(startIdx, idxOld));
// add aNewPattern to take place of aOldPattern
result.append(aNewPattern);

// reset the startIdx to just after the current match, to see
// if there are any further matches
startIdx = idxOld + aOldPattern.length();
}
// the final chunk will go to the end of aInput
result.append(aInput.substring(startIdx));
return result.toString();
}

public static String replaceOld(final String aInput, final String aOldPattern, final String aNewPattern) {
if (aOldPattern.equals("")) {
throw new IllegalArgumentException("Old pattern must have content.");
}

final StringBuffer result = new StringBuffer();
// startIdx and idxOld delimit various chunks of aInput; these
// chunks always end where aOldPattern begins
int startIdx = 0;
int idxOld = 0;
while ((idxOld = aInput.indexOf(aOldPattern, startIdx)) >= 0) {
// grab a part of aInput which does not include aOldPattern
result.append(aInput.substring(startIdx, idxOld));
// add aNewPattern to take place of aOldPattern
result.append(aNewPattern);

// reset the startIdx to just after the current match, to see
// if there are any further matches
startIdx = idxOld + aOldPattern.length();
}
// the final chunk will go to the end of aInput
result.append(aInput.substring(startIdx));
return result.toString();
}

//to find out the index of the occurances of the substring in the original String
//This list stores the starting index of subString incase it is present multiple times

private static List listOfIndecesOfSubstring(String label, String subString) {

int i = 0;
for (i = 0; i < label.length(); i++) {

int j = 0;

if (label.charAt(i) == subString.charAt(j)) {
int k = i + 1;
j++;

for (; j < subString.length(); j++,k++) {
if (label.charAt(k) != subString.charAt(j)) {
break;
}
}

if (subString.length() == j) {
mIndex.add(String.valueOf(i));
}
}

}
mIndex.trimToSize();
return mIndex;
}

//to replace the substring with newString
private static String replaceAll(char[] actual_sentence,char[] arrayToBeReplaced, char[] newArray){

char[] final_sentence = new char[actual_sentence.length + (newArray.length - arrayToBeReplaced.length)*mIndex.size()];
int arrayListIndex = 0;
int k = 0;
for(int i=0;i< actual_sentence.length;i++,k++){

int occurAtIndex = Integer.valueOf((String)mIndex.get(arrayListIndex));

if(i != occurAtIndex){
final_sentence[k]=actual_sentence[i];
}else{
for(int j = 0;j < newArray.length;j++,k++){
final_sentence[k]= newArray[j];
}
arrayListIndex++;
i=i+arrayToBeReplaced.length -1;
k=k-1;
}

}
return new String(final_sentence);
}