CODEWITHSUNDEEP
javastringstring-parsing
Raghuram Vadapalli
Raghuram Vadapalli

Reputation: 1240

Java Replace multiple substrings(based on indexes)

I have a string like 

'John is a student. He is also a researcher. He is also a human.'

I have start and end indexes of John and first He. Is there a way to replace these substrings simultaneously with x. Note that I should not replace second He because I have indexes only for the first He.

We can obviously iterate over string, copy whenever the pointer is not in the window of substring and putting x instead. But, is there a better way than this?

Also, note that indexes are non-overlapping.

Upvotes: 0

Views: 1498

Answers (4)

Raghuram Vadapalli
Raghuram Vadapalli

Reputation: 1240

Replacing from the end is the best solution.

public class NE {
     public Integer startIndex;
     public Integer endIndex;
}

public class CustomComparator implements Comparator<NE> {
    public int compare(NE n1, NE n2) {
        return n1.startIndex.compareTo(n2.startIndex);
    }
}

ArrayList<NE> NEList = getIndexes();
Collections.sort(NEList, ner.new CustomComparator());

String finalString = 'John is a student. He is also a researcher. He is also a human.';
for(int i=NEList.size()-1;i>=0;i--){
    NE ne = ner.new NE();
    ne = NEList.get(i);
    finalString = new StringBuilder(finalString).replace(ne.startIndex, ne.endIndex, 'x').toString();
}
System.out.println(finalString);

Credits: @AndyTurner

Upvotes: 3

Mario Cairone
Mario Cairone

Reputation: 1144

You can use a placeholder with the same lenght of the word to replace.Then replace the placeholders with x and get the result.

 String s = "John is a student. He is also a researcher.";
 int firstStart = 0,firstEnd =4,secondStart=19,secondEnd=21;

 String firstPlaceholder = String.format("%"+(firstEnd - firstStart )+"s", " ").replaceAll(" ", "x");
 String secondPlaceholder = String.format("%"+(secondEnd -secondStart)+"s", " ").replaceAll(" ", "x");

 String result = new StringBuilder(s).replace(firstStart, firstEnd, firstPlaceholder)
                                        .replace(secondStart, secondEnd, secondPlaceholder)
                                        .toString().replaceAll("x[x]+", "x");
 System.out.println( result);

output:

x is a student. x is also a researcher.

hope this can help.

Upvotes: 0

Amar Bessalah
Amar Bessalah

Reputation: 119

try this :

String s="John is a student. He is also a researcher.";

        int beginIndex=s.indexOf("He");
        s=s.substring(0, beginIndex)+"x"+s.substring(beginIndex+2,s.length());

Output : John is a student. x is also a researcher.

Upvotes: 0

Robert van der Spek
Robert van der Spek

Reputation: 1227

I do not know about a way to change both with the index. But hey, you probably first found the index by searching for the substrings John and He. So you could skip that and use the Strings static method replaceAll.

String test = "John is a student. He is also a researcher.";
System.out.println(test.replaceAll("(John)|(He)", "x"));

In fact you are checking if (John)|(He) ("John" or "He") are in the string test. If so they are replaced by "x".

replaceAll returns a reference to a new String object looking like:

x is a student. x is also a researcher.

Upvotes: 0

Related Questions