/* 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 myString = "hello_AD123.mp3";
		myString = myString.replaceFirst("_.*[.]", ".");
		// OR myString = myString.replaceFirst("_[^.]*", "");
		System.out.println(myString);
	}
}

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