/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {
        String text = "Текст#abc\nТекст#abc\nТекст#abc";
        String toReplace = "abc";
 
        System.out.println(text);
        System.out.println();
 
        int number = 1;
 
        while (text.contains(toReplace)) {
            text = text.replaceFirst(toReplace, "" + number);
            number++;
        }
 
        System.out.println(text);
    }
}

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