wordsFront challenge

gudii9
gudii9 used Ask the Experts™
on
Hi,

I am working on below challenge
http://codingbat.com/prob/p183837

Psedo code:
1. create new array of given n size
2. loop through given array
3. fill the new array with given array
4. return new array
I wrote my code as below

public String[] wordsFront(String[] words, int n) {
 int count=0;
 String[] arr=new String[n];
for(int i=0;i<n;i++){
  arr[i]=words[i];
  
 
}
return arr;
}

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I am passing all tests

How to improve/modify my design, code and any other alternate approaches. please advise
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CPColinSenior Java Architect
Commented:
Your line 2 there does nothing. The only way you could really change anything here is by using System.arrayCopy(), which performs essentially the same operation as the loop you've written. Looks like that website doesn't let you do that, though.
Yes, you could make it a bit shorter . . .

public String[] wordsFront(String[] words, int n) {
  return Arrays.copyOfRange(words,  0,  n);
}

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using System.arrayCopy(),

I have said before that Codingbat does not permit System calls ! How could it? Where do you suppose that  output would go ??
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CPColinSenior Java Architect

Commented:
Well arrayCopy() doesn't do output, so there's no technical reason to disallow that specific method. Interesting that they allowed Arrays, without a package name; they must be importing stuff from java.util behind the scenes.
It's the SYSTEM API call that's wrong!!!
CPColinSenior Java Architect

Commented:
I'm not sure what you're on about. I know the site disallows use of members of the System class, seeing as I mentioned that in my first comment.

Author

Commented:
package com.solution;



	import java.lang.*;

	public class SystemDemo {

	   public static void main(String[] args) {

	   int arr1[] = { 0, 1, 2, 3, 4, 5 };
	   int arr2[] = { 5, 10, 20, 30, 40, 50 };
	    
	   // copies an array from the specified source array
	   System.arraycopy(arr1, 0, arr2, 0, 2);
	   System.out.print("array2 = ");
	   System.out.print(arr2[0] + " ");
	   System.out.print(arr2[1] + " ");
	   System.out.print(arr2[2] + " ");
	   System.out.print(arr2[3] + " ");
	   System.out.print(arr2[4] + " ");
	   }
	}

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array2 = 0 1 20 30 40
something like above instead of 2 give n but coding bat wont allow with System class methods but allows Array class methods which is bit strange

Author

Commented:
package com.solution;

import java.lang.*;
import java.util.Arrays;

public class SystemDemo2 {

	public static void main(String[] args) {
		String words[] = { "a", "b", "c", "d" };
		System.out.println("vslue is--->" + Arrays.toString(wordsFront(words, 1)));		

	}

	public static String[] wordsFront(String[] words, int n) {
		String[] newwords = new String[n];
		// copies an array from the specified source array
		System.arraycopy(words, 0, newwords, 0, 1);
		// System.out.print("array2 = ");
		System.out.print(newwords[0] + " ");
		// System.out.print(newwords[1] + " ");
		// System.out.print(arr2[2] + " ");
		// System.out.print(arr2[3] + " ");
		// System.out.print(arr2[4] + " ");
		// return System.arraycopy(words, 0,newwords,0, n);
		return newwords;

	}

}

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eclipse it is working fine

a vslue is--->[a]

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