String Replace Problem

[Eric Paul]

Hi, I'm rather new to Java. I would like to know why the following code doesn't work. I'm trying to parse the String named "string". My delimiters are topic, location, presenter and end. I try to loop through the string to grab all three instances (you'll notice there are three topics). However, after the second loop, it resets itself and gives me the same output as the first pass. Any ideas?

public class test
{
      public static void main(String[] args) 
		{
			int a,b,c,d;
		  	String result = "";
		  	String result2 = "";
		  	String result3 = ""; 
		  	String topic = "Topic:"; 	
			String location = "Location:"; 
		  	String presenter = "Presenter:";
			String end = "NEXT";
		    String string = "Topic: Science Location: West Presenter: Joe  NEXT "
                  + "Topic: Math Location: East Presenter: Sally NEXT Topic: Algebra Location: Central Presenter: Mike NEXT"; 

		  	a = string.indexOf(topic);
		  	b = string.indexOf(location);
		  	c = string.indexOf(presenter);
			d = string.indexOf(end);


		  	result = string.substring(a, b);
        	   result2 = string.substring(b, c); 
		result3 = string.substring(c, d);
			
			for(int i=0; i < 3; i++) {
			  	String s = new String(result + result2 + result3 + end);
			  	String newStmt = string.replaceAll(s,"");
				a = newStmt.indexOf(topic);
			  	b = newStmt.indexOf(location);
			  	c = newStmt.indexOf(presenter);
				d = newStmt.indexOf(end);
				result = newStmt.substring(a,b);
			        result2 = newStmt.substring(b,c);
			       result3 = newStmt.substring(c,d);
				System.out.println(result + result2 + result3);
			//Current Output
                            //Topic: Math Location: East Presenter: Sally 
    			     //Topic: Science Location: West Presenter: Joe  
    			       //Topic: Math Location: East Presenter: Sally
			}
	}

[Ulf Dittmer]

Welcome to JavaRanch.

I'll bet that the replaceAll statement does nothing, and so newStmt = string.

Try something like "string = string.substring(string.indexOf(end) + end.length())". Then you don't need "newStmt".

[Henry Wong]

Basically...

First, outside of the loop, you extract the first item, but you don't print it...

Next, when you enter the loop, you remove the first item from the string, and you extract the second item. This (second item) is the first item that will be printed.

Next, on the next iteration of the loop, you remove the second item from the string. However, this is the orginal string, so all three items are still present, so you extract the first item again. This (first item) is the second item that will be printed.

Next, on the next iteration of the loop, you remove the first item from the string. However, this is the orginal string, so all three items are still present, so you extract the second item again. This (second item) is the third item that will be printed.

If your loop kept going, your program will be toggling between the first and second items...

Henry

[Eric Paul]

Ahh, I see now. So, I'm only removing a piece of the string at any time. I actually need to:

1. Print the line I selected
2. Completely delete that from the string
3. Print the next line
etc.

I'll give it a shot. I may have more questions.

[Eric Paul]

Hi guys, thanks for your help on this. This is how I ended up completing it. Probably not the most efficient way, but it works.

public class SubstringExample4
{
      public static void main(String[] args) 
		{
			int a,b,c;
		  	String result = "";
		  	String result2 = "";
		  	String result3 = "";
			String str = "";
		  	String topic = "Topic:"; 	
			String location = "Location:"; 
		  	String presenter = "Presenter:";

		   String string = "Topic: Science Location: West Presenter: Joe  NEXT Topic: Math Location: East Presenter: Sally NEXT Topic: Algebra Location: Central Presenter: Mike NEXT"; 

			String[] temp;

			String delimeter = "NEXT";
			
			temp = string.split(delimeter);
						
		   for(int i =0; i < temp.length ; i++) {
		   		str = temp[i];
					a = str.indexOf(topic);
		  			b = str.indexOf(location);
		  			c = str.indexOf(presenter);
					result = str.substring(a, b);
        			result2 = str.substring(b, c); 
					result3 = str.substring(c);
					System.out.println(result);
					System.out.println(result2);
					System.out.println(result3);
					System.out.println("---------");
				}
		}
}