Remove all Occurrence

This is number 2 from handout #4 : string processing.

/*
* RemoveAllOccurences
*/

import acm.program.*;

public class RemoveAllOccurences extends ConsoleProgram{
	public void run(){	
		while(true){													// infinite loop
			String str1 = readLine("Give me a string(q to exit): ");	// q as a sentinel to break out of the loop
			if(str1.equals("q"))				
				break;
			String str2 = readLine("Give me a character to remove: ");	// give me the char
			
			int charIndex = 0;											// get the first char only
			char ch = str2.charAt(charIndex);							// 
			
			println(removeAllOccurrence(str1,ch));						// call removeAllOccurence
		}
	}
	
	// remove all occurrence of a char in a string
	private String removeAllOccurrence(String str, char ch){
		String result = ""; 								// declare a new String object result
		int firstIndex = 0;									// beginning of the string
		int indexChar =str.indexOf(ch);						// find the index of the first occurrence
		while(indexChar!=-1){ 								//loop through the string str until we find all occurrence
			result+=str.substring(firstIndex,indexChar);	//iterate 
			firstIndex = indexChar+1;						// skip the char
			indexChar = str.indexOf(ch, firstIndex);		// get the next index of the next substring
		}
		return result+str.substring(firstIndex);			//add the end of the result string and return it
	}
}