java:implement 8 queen using depth first search

Question

i am try to implement 8 queen using depth search for any initial state it work fine for empty board(no queen on the board) ,but i need it to work for initial state if there

Answer 1

[EDIT: Added conditional output tip.]

To add to @StephenC's answer:

This is a heck of a complicated piece of code, especially if you're not experienced in programming Java.

I executed your code, and it outputs this over and over and over and over (and over)

back at (0,0)
 01234567
0
1 Q
2  Q
3   Q
4    Q
5     Q
6      Q
7       Q
back at (0,0)

And then crashes with this

Exception in thread "main" java.lang.StackOverflowError
    at java.nio.Buffer.(Unknown Source)
    ...
    at java.io.PrintStream.print(Unknown Source)
    at java.io.PrintStream.println(Unknown Source)
    at Depth.eightQueen(Depth.java:56)
    at Depth.eightQueen(Depth.java:60)
    at Depth.eightQueen(Depth.java:60)
    at Depth.eightQueen(Depth.java:60)
    at Depth.eightQueen(Depth.java:60)
    ...

My first instinct is always to add some System.out.println(...)s to figure out where stuff is going wrong, but that won't work here.

The only two options I see are to

• Get familiar with a debugger and use it to step through and analyze why it's never stopping the loop
• Break it down man! How can you hope to deal with a massive problem like this without breaking it into digestible chunks???

Not to mention that the concept of 8-queens is complicated to begin with.

---

One further thought:

System.out.println()s are not useful as currently implemented, because there's infinite output. A debugger is the better solution here, but another option is to somehow limit your output. For example, create a counter at the top

private static final int iITERATIONS = 0;

and instead of

System.out.println("[ANUMBERFORTRACING]: ... USEFUL INFORMATION ...")

use

conditionalSDO((iITERATIONS < 5), "[ANUMBERFORTRACING]: ... USEFUL INFORMATION");

Here is the function:

private static final void conditionalSDO(boolean b_condition, String s_message)  {
   if(b_condition)  {
       System.out.println(s_message);
   }
}

Another alternative is to not limit the output, but to write it to a file.

I hope this information helps you.

(Note: I edited the OP's code to be compilable.)