Getting a ArrayIndexOutOfBoundsException.

[Aditya Sirohi]

Hello,

I am getting this error while compiling this class below. The error is:-
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
at Path.getShareableEntFolder(Path.java:52)
at Path.main(Path.java:16)

When i try to change

static String array2[] = new String[getShare()];

to

static String array2[] = new String[520];

it works fine. What might be the issue Help is appreciated.

import java.io.File;


 class Path {
	static String path = "/net/vol/mages/spins/7/";
	static String platform ="nt";
	static String ga_build_number = "7.1";
	
	static String array1[] = new String[arraySize("/net/vol/mages/spins/7/")];
	static String array2[] = new String[getShare()];
	
 public static  void main(String[] args){
	 	arraySize(path);
		pushInArray();
		getShare();
		getShareableEntFolder(); 
		
		//testMethod();
 }
 
 
 public static void testMethod(){
	 for(int i=0; i<array2.length;i++){
		 System.out.println(array2[i]);
	 }
 }
 public static int getShare(){
	 int k = 0;
	 for(int i=0; i<array1.length;i++){
			File su = new File(path+array1[i]+"/"+ga_build_number+"/"+platform+"/"+"ShareableEntities");
			if(su.isDirectory()){
				String[] test = su.list();
				for(int i1=0; i1< test.length; i1++){
					k++;			
				}
			}
	 }
	 return k;
 }
 
 public static void getShareableEntFolder(){
	 int j = 0;
	for(int i=0; i<array1.length;i++){
		//System.out.println(array1[i]);
		File su = new File(path+array1[i]+"/"+ga_build_number+"/"+platform+"/"+"ShareableEntities");
		if(su.isDirectory()){
			String[] test = su.list();
			
			for(int i1=0; i1< test.length; i1++){
				//System.out.println("this is it" +test[i1]);
				String a = path+array1[i]+"/"+ga_build_number+"/"+platform+"/"+"ShareableEntities"+"/"+test[i1];
				array2[j] = a;
				j++;
			}
		}
	}
	System.out.println("this is the value of j" +j);
 }
 
 
 //This method return the Offering inside the stream.
 public static void pushInArray(){
	 int j = 0;
	 File offerings = new File(path);
	 if(offerings.isDirectory()){
		 String[] test = offerings.list();
		 for(int i=0; i< test.length; i++){
			 
			 array1[j] = test[i]; 
			 j++;
		 }
	 }
 }
 

	 
 public static int arraySize(String Path){
	     int j =0;
		 File offerings = new File(Path);
		 if(offerings.isDirectory()){
			 String[] test = offerings.list();
			 for(int i=0; i< test.length; i++){
				// System.out.println(test[i]); 
				 j++;
			 }
		 }
		 return j;
	 }
 
}

[Henry Wong]

Aditya Sirohi wrote:
I am getting this error while compiling this class below. The error is:-
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
at Path.getShareableEntFolder(Path.java:52)
at Path.main(Path.java:16)

The stack trace is telling you most of the story. If you look, you will see that the exception is thrown when trying to access element zero. This means that there isn't an element zero, which states that the array is of size zero. You should probably confirm this by adding a line of debugging code.

Obviously, you didn't want your array to have no elements, so I would recommend to take another look at the initialization to see what is wrong.

Henry

[Aditya Sirohi]

Hello Henry

Obviously, you didn't want your array to have no elements, so I would recommend to take another look at the initialization to see what is wrong.

But when i try to print the value of "k" from getShare() method, i get a value of 512. which should be initialized when array is given a size:- static String array2[] = new String[getShare()];
Could you tell me more what i am doing wrong?

 public static int getShare(){  
     int k = 0;  
      for(int i=0; i<array1.length;i++){  
             File su = new File(path+array1[i]+"/"+ga_build_number+"/"+platform+"/"+"ShareableEntities");  
             if(su.isDirectory()){  
                 String[] test = su.list();  
                 for(int i1=0; i1< test.length; i1++){  
                     k++;              
                 }  
             }  
      }  
      System.out.println(k);
      return k;  
  }  

[Henry Wong]

Aditya Sirohi wrote:
But when i try to print the value of "k" from getShare() method, i get a value of 512. which should be initialized when array is given a size:- static String array2[] = new String[getShare()];
Could you tell me more what i am doing wrong?

Hint: When did you "try to print the value of "k" from getShare() method? At the time that it is called? Or did you call it separately?

Another way to ask it. You call getShare() many times. Do they *all* return 512?

Henry

[Aditya Sirohi]

Humm, its strange array2[] has the value zero. i tried to print its length in the testMethod(). Why is the value of the array zero?

Thanks
Aditya

 public static void testMethod(){
	// for(int i=0; i<array2.length;i++){
		// System.out.println(array2[i]);
	 //}
	 System.out.println(array2.length);
 }

[Henry Wong]

Aditya Sirohi wrote:Why is the value of the array zero?

Same hint: Does all calls to the getShare() method produce the same value? Does one of them return zero? What is different about that call?

Another hint: What happens when not all of the resources used by getShare() are initialized yet?

Henry

[Aditya Sirohi]

Hello Henry,

I have a potential problem here, the getShare() method printed value of k as zero and 512. Why is that so?

Thanks
Aditya

 public static int getShare(){  
      int k = 0;  
      for(int i=0; i<array1.length;i++){  
             File su = new File(path+array1[i]+"/"+ga_build_number+"/"+platform+"/"+"ShareableEntities");  
             if(su.isDirectory()){  
                 String[] test = su.list();  
                 for(int i1=0; i1< test.length; i1++){  
                     k++;              
                 }  
             }  
      }
      System.out.println(k);  
      return k;  
  } 

[Henry Wong]

Read my hints again

[Rob Prime]

Does it always print 512, or just the last time you call it?

[Aditya Sirohi]

Hello Rob/Henry,

I have faced this issue first time So i want some ideas and reason what wrong i am doing here. So in this class below getShare() method print value of XX as 512.

import java.io.File;

 class Path {
	 
	static String path = "/net/vol/local/spins/7/";
	static String platform ="nt_i386";
	static String ga_build_number = "7.1.1.D091201A";
	
	
	static String array1[] = new String[arraySize("/net/vol/local/spins/7/")];
	
 public static  void main(String[] args){
		pushInArray();
		getShare();
 }

 public static int getShare(){
	 int XX = 0;
	 for(int a=0; a<array1.length;a++){
			File su = new File(path+array1[a]+"/"+ga_build_number+"/"+platform+"/"+"ShareableEntities");
			boolean exists = su.exists();
			if(exists){
				String[] test = su.list();
				for(int b=0; b< test.length; b++){
					XX++;			
				}
			}
	 }
	 System.out.println(XX);
	 return XX;
 }
 
 public static int arraySize(String Path){
	     int j =0;
		 File offerings = new File(Path);
		 if(offerings.isDirectory()){
			 String[] test = offerings.list();
			 for(int i=0; i< test.length; i++){
				 j++;
			 }
		 }
		 return j;
	 }
 
 public static void pushInArray(){
	 int j = 0;
	 File offerings = new File(path);
	 if(offerings.isDirectory()){
		 String[] test = offerings.list();
		 for(int i=0; i< test.length; i++){
			 array1[j] = test[i]; 
			 j++;
		 }
	 }
 }
 
 
}

But when i change the code and try to call the getShare() method inside array2[] so that array2[] can be initialized to the value of XX i get from getShare(). But length for array2[] is zero where at it should be value of XX which is returned from getShare(), ie 512. What is the problem. I want array2[] to get the value of getShare(). I need to tweek something let me know.

import java.io.File;

 class Path {
	 
	static String path = "/net/vol/local/spins/7/";
	static String platform ="nt_i386";
	static String ga_build_number = "7.1.1.D091201A";
	
	
	static String array1[] = new String[arraySize("/net/vol/local/spins/7/")];
	static String array2[] = new String[getShare()];
	
 public static  void main(String[] args){
		pushInArray()
		testMethod();
 }
 
 
 public static void testMethod(){
	
	 System.out.println("array2 length" +array2.length);
 }
 

 public static int getShare(){
	 int XX = 0;
	 for(int a=0; a<array1.length;a++){
			File su = new File(path+array1[a]+"/"+ga_build_number+"/"+platform+"/"+"ShareableEntities");
			boolean exists = su.exists();
			if(exists){
				String[] test = su.list();
				for(int b=0; b< test.length; b++){
					XX++;			
				}
			}
	 }
	 System.out.println(XX);
	 return XX;
 }
 
 public static int arraySize(String Path){
	     int j =0;
		 File offerings = new File(Path);
		 if(offerings.isDirectory()){
			 String[] test = offerings.list();
			 for(int i=0; i< test.length; i++){
				 j++;
			 }
		 }
		 return j;
	 }
 
 public static void pushInArray(){
	 int j = 0;
	 File offerings = new File(path);
	 if(offerings.isDirectory()){
		 String[] test = offerings.list();
		 for(int i=0; i< test.length; i++){
			 array1[j] = test[i]; 
			 j++;
		 }
	 }
 }
 
 
}

[Henry Wong]

Note: I am not just giving you hints because I want to make you jump through hoops. I know exactly what the problem is, and is trying to get you to see it. Please take a look at the hints. The answer is there. So....


hint: What happens when not all of the resources used by getShare() are initialized yet?

[Aditya Sirohi]

hint: What happens when not all of the resources used by getShare() are initialized yet?

I guess array2[] is initialized to value to a value zero. But what is that resource, i really cant see it.

[Henry Wong]

Aditya Sirohi wrote:
But what is that resource, i really cant see it.

Take a look at the getShare() method, and tell me, what variables, that are external to the method, that it depends on?


And BTW, I am going to ignore the sarcastic part of your answer.

Henry

[Aditya Sirohi]

Henry asked?
Take a look at the getShare() method, and tell me, what variables, that are external to the method, that it depends on?

I think they are array1, platform, ga_build_number and path.

[Henry Wong]

Aditya Sirohi wrote:
I think they are array1, platform, ga_build_number and path.

Now... next question... when are all four of those variables all initialized?


And since I am going to bed now... the next next question is... At the time the getShare() method is called to create the array2 array, did that [ANSWER_FROM_FIRST_QUESTION] get called yet?

Henry

[Aditya Sirohi]

Thanks Henry,

You are a great guide . So it was my eyes that could not figure this out. So i called pushInArray(). Have a good night. Marking this String as resolved.

Thanks
Aditya

 public static int getShare(){  
    pushInArray();
      int XX = 0;  
      for(int a=0; a<array1.length;a++){  
             File su = new File(path+array1[a]+"/"+ga_build_number+"/"+platform+"/"+"ShareableEntities");  
             boolean exists = su.exists();  
             if(exists){  
                 String[] test = su.list();  
                for(int b=0; b< test.length; b++){  
                     XX++;             
                 }  
             }  
      }  
      System.out.println(XX);  
      return XX;  
 }