Thread: Spaceship question...

Originally Posted by Norm

Try debugging by adding some println() statements that print out what was read from the file (dist) and what is in the array(distance). The print out will help you understand what the code is doing.
To print the contents of an array:
System.out.println("an ID "+ java.util.Arrays.toString(theArrayNameHere));

yea this is what i got--------------------Configuration: <Default>--------------------
1280
1280
1280
1280
1280
1280
1280
1280
1280
1280
720
720
720
720
720
720
720
720
720
720
900
900
900
900
900
900
900
900
900
900
1400
1400
1400
1400
1400
1400
1400
1400
1400
1400
500
500
500
500
500
500
500
500
500
500
200
200
200
200
200
200
200
200
200
200
360
360
360
360
360
360
360
360
360
360
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100110011001100110011001100110011001100%d [1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100]

Originally Posted by Norm

That shows all the elements in the array have the same value (the value of the last item read).

Now are you ready to work on the logic?
If so work on what was suggested earlier:
Ok, what simple steps should the code take to do that? Can you make a list of the steps that can be used as a guide to write the code?

ut my code is reading data from the file. but why is it only displaying the same value?

Originally Posted by Norm

Because the logic is wrong. You need change the logic.

ok but how. I dont see where im getting the error. and i placed println all over. which line do i have to change?

Originally Posted by Norm

Before writing anymore code, make a list of the steps the code needs to do to read in the values from the file and save them in an array. Once the steps are worked out, then try writing the code.

1.read value from file
2.store in array.

i did that but its not working

Originally Posted by Norm

That logic only shows one record being read from the file. The program must read more than one record.
What are the steps needed to store a value into an array?
For example:
assign a value to the index
store value into array at the location pointed to by the index

The whole program from your logic would be:

  int i=0;                  // define an index for the array
  int dist=in.nextInt();  //read value from file
  distance[i]=dist;       //store in array

If you want to do more than that, you need a loop and code to change the index.

i did that but when i run the program im getting this:

--------------------Configuration: <Default>--------------------
Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:907)
at java.util.Scanner.next(Scanner.java:1530)
at java.util.Scanner.nextInt(Scanner.java:2160)
at java.util.Scanner.nextInt(Scanner.java:2119)
at test.main(test.java:9)

Process completed.

Originally Posted by Norm

I don't know what you did without seeing the code.
Please post the code for the program that gets that error.

ok now its just printing the last number from the file 10 times

int [] distance = new int [10];//array of size 10
int dist=in.nextInt();//read first value from file
int i;
while (dist!=0){//while value is not equal to 0 do
 
	 for(i=0;i<distance.length;i++){//loops from 1st value to last value
	 	   distance[i]=dist;//set dist to 1st location in array       
	 }//end for	 	   
dist=in.nextInt();//read next value
   }//end while
 
int temp,count;
for(i=dist;i <distance.length;i++){
	for(int j=i+1;j<distance.length;j++){
 
		if(distance[j] < distance[i]){
			temp=distance[j];
			distance[j]=distance[i];
			distance[i]=temp;		
		}
	}
	System.out.printf("%d",distance[i]);
}
 
       in.close();
      }//end main
	}//end class

Originally Posted by Norm

Please edit your post and format the code.

Also please post code that will compile and execute for testing, not just a small bit that can't be tested.

import java.util.*;
import java.io.*;
public class Spaceship{
	public static void main(String[]args)throws IOException{
		Scanner in = new Scanner(new FileReader("distances.txt"));	
int [] distance = new int [10];//array of size 10
int dist=in.nextInt();//read first value from file
int i;
while (dist!=0){//while value is not equal to 0 do
 
	 for(i=0;i<distance.length;i++){//loops from 1st value to last value
	 	   distance[i]=dist;//set dist to 1st location in array       
	 }//end for	 	   
dist=in.nextInt();//read next value
   }//end while
 
int temp,count;
for(i=dist;i <distance.length;i++){
	for(int j=i+1;j<distance.length;j++){
 
		if(distance[j] < distance[i]){
			temp=distance[j];
			distance[j]=distance[i];
			distance[i]=temp;		
		}
	}
	System.out.printf("%d",distance[i]);
}
 
       in.close();
      }//end main
	}//end class

its stll only reading and displaying the same value

Originally Posted by Norm

This has been discussed many times.
The logic is wrong. You need to change the logic.
The problem was pointed to in posts#12 and 21

yea i saw the posts but that does not tell me anything. How is the logic incorrect?where? how do i changed the logic?

Originally Posted by Norm

What does that for loop do?
What is the contents of the array after the for loop executes? Print its contents with this statement:
System.out.println("an ID "+ java.util.Arrays.toString(theArrayName));
immediately after the for loop ends.

this is what it printed
--------------------Configuration: <Default>--------------------
%d [1280, 0, 0, 0, 0, 0, 0, 0, 0, 0]
%d [1280, 1280, 0, 0, 0, 0, 0, 0, 0, 0]
%d [1280, 1280, 1280, 0, 0, 0, 0, 0, 0, 0]
%d [1280, 1280, 1280, 1280, 0, 0, 0, 0, 0, 0]
%d [1280, 1280, 1280, 1280, 1280, 0, 0, 0, 0, 0]
%d [1280, 1280, 1280, 1280, 1280, 1280, 0, 0, 0, 0]
%d [1280, 1280, 1280, 1280, 1280, 1280, 1280, 0, 0, 0]
%d [1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 0, 0]
%d [1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 0]
%d [1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280]
%d [720, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280]
%d [720, 720, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280]
%d [720, 720, 720, 1280, 1280, 1280, 1280, 1280, 1280, 1280]
%d [720, 720, 720, 720, 1280, 1280, 1280, 1280, 1280, 1280]
%d [720, 720, 720, 720, 720, 1280, 1280, 1280, 1280, 1280]
%d [720, 720, 720, 720, 720, 720, 1280, 1280, 1280, 1280]
%d [720, 720, 720, 720, 720, 720, 720, 1280, 1280, 1280]
%d [720, 720, 720, 720, 720, 720, 720, 720, 1280, 1280]
%d [720, 720, 720, 720, 720, 720, 720, 720, 720, 1280]
%d [720, 720, 720, 720, 720, 720, 720, 720, 720, 720]
%d [900, 720, 720, 720, 720, 720, 720, 720, 720, 720]
%d [900, 900, 720, 720, 720, 720, 720, 720, 720, 720]
%d [900, 900, 900, 720, 720, 720, 720, 720, 720, 720]
%d [900, 900, 900, 900, 720, 720, 720, 720, 720, 720]
%d [900, 900, 900, 900, 900, 720, 720, 720, 720, 720]
%d [900, 900, 900, 900, 900, 900, 720, 720, 720, 720]
%d [900, 900, 900, 900, 900, 900, 900, 720, 720, 720]
%d [900, 900, 900, 900, 900, 900, 900, 900, 720, 720]
%d [900, 900, 900, 900, 900, 900, 900, 900, 900, 720]
%d [900, 900, 900, 900, 900, 900, 900, 900, 900, 900]
%d [1400, 900, 900, 900, 900, 900, 900, 900, 900, 900]
%d [1400, 1400, 900, 900, 900, 900, 900, 900, 900, 900]
%d [1400, 1400, 1400, 900, 900, 900, 900, 900, 900, 900]
%d [1400, 1400, 1400, 1400, 900, 900, 900, 900, 900, 900]
%d [1400, 1400, 1400, 1400, 1400, 900, 900, 900, 900, 900]
%d [1400, 1400, 1400, 1400, 1400, 1400, 900, 900, 900, 900]
%d [1400, 1400, 1400, 1400, 1400, 1400, 1400, 900, 900, 900]
%d [1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 900, 900]
%d [1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 900]
%d [1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400]
%d [500, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400]
%d [500, 500, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400]
%d [500, 500, 500, 1400, 1400, 1400, 1400, 1400, 1400, 1400]
%d [500, 500, 500, 500, 1400, 1400, 1400, 1400, 1400, 1400]
%d [500, 500, 500, 500, 500, 1400, 1400, 1400, 1400, 1400]
%d [500, 500, 500, 500, 500, 500, 1400, 1400, 1400, 1400]
%d [500, 500, 500, 500, 500, 500, 500, 1400, 1400, 1400]
%d [500, 500, 500, 500, 500, 500, 500, 500, 1400, 1400]
%d [500, 500, 500, 500, 500, 500, 500, 500, 500, 1400]
%d [500, 500, 500, 500, 500, 500, 500, 500, 500, 500]
%d [200, 500, 500, 500, 500, 500, 500, 500, 500, 500]
%d [200, 200, 500, 500, 500, 500, 500, 500, 500, 500]
%d [200, 200, 200, 500, 500, 500, 500, 500, 500, 500]
%d [200, 200, 200, 200, 500, 500, 500, 500, 500, 500]
%d [200, 200, 200, 200, 200, 500, 500, 500, 500, 500]
%d [200, 200, 200, 200, 200, 200, 500, 500, 500, 500]
%d [200, 200, 200, 200, 200, 200, 200, 500, 500, 500]
%d [200, 200, 200, 200, 200, 200, 200, 200, 500, 500]
%d [200, 200, 200, 200, 200, 200, 200, 200, 200, 500]
%d [200, 200, 200, 200, 200, 200, 200, 200, 200, 200]
%d [360, 200, 200, 200, 200, 200, 200, 200, 200, 200]
%d [360, 360, 200, 200, 200, 200, 200, 200, 200, 200]
%d [360, 360, 360, 200, 200, 200, 200, 200, 200, 200]
%d [360, 360, 360, 360, 200, 200, 200, 200, 200, 200]
%d [360, 360, 360, 360, 360, 200, 200, 200, 200, 200]
%d [360, 360, 360, 360, 360, 360, 200, 200, 200, 200]
%d [360, 360, 360, 360, 360, 360, 360, 200, 200, 200]
%d [360, 360, 360, 360, 360, 360, 360, 360, 200, 200]
%d [360, 360, 360, 360, 360, 360, 360, 360, 360, 200]
%d [360, 360, 360, 360, 360, 360, 360, 360, 360, 360]
%d [1100, 360, 360, 360, 360, 360, 360, 360, 360, 360]
%d [1100, 1100, 360, 360, 360, 360, 360, 360, 360, 360]
%d [1100, 1100, 1100, 360, 360, 360, 360, 360, 360, 360]
%d [1100, 1100, 1100, 1100, 360, 360, 360, 360, 360, 360]
%d [1100, 1100, 1100, 1100, 1100, 360, 360, 360, 360, 360]
%d [1100, 1100, 1100, 1100, 1100, 1100, 360, 360, 360, 360]
%d [1100, 1100, 1100, 1100, 1100, 1100, 1100, 360, 360, 360]
%d [1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100, 360, 360]
%d [1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100, 360]
%d [1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100]

Originally Posted by Norm

Now what about the for loop.
What is the for loop supposed to do? The printout shows you what it does.
This is what the array should have in it after the first record is read and saved:
[1280, 0, 0, 0, 0, 0, 0, 0, 0, 0]
and this is what it should have in it after the second record:
[1280, 720, 0, 0, 0, 0, 0, 0, 0, 0]
and after the third:
[1280, 720, 900, 0, 0, 0, 0, 0, 0, 0]

Where is the println() that printed what's in post#42? It looks like it is inside of the for loop,
not after the for loop as suggested in post#41

yea i mis read when u said to place it outside the loop.
this is what it prints
--------------------Configuration: <Default>--------------------
an ID [1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280, 1280]
an ID [720, 720, 720, 720, 720, 720, 720, 720, 720, 720]
an ID [900, 900, 900, 900, 900, 900, 900, 900, 900, 900]
an ID [1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400, 1400]
an ID [500, 500, 500, 500, 500, 500, 500, 500, 500, 500]
an ID [200, 200, 200, 200, 200, 200, 200, 200, 200, 200]
an ID [360, 360, 360, 360, 360, 360, 360, 360, 360, 360]
an ID [1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100, 1100]

Originally Posted by Norm

Actually the other post's print out showed more.

what about the for loop?

i think the for loop increments to store the next value in the array. But my time is up anyway. Submitted 5 mins ago. :/