getting error when converting vector to string

[Prabhudatta Choudhury]

Hi Guys,

I faced problem in converting a vector to String. I'm giving the code below. Please let me know how can i do that.

import java.util.*;
public class Test {

private static Vector v1 = new Vector();
private static String[] sarr = null;
private static String   s1 = " ";
private static int count =0;

public static void main(String a[])
{

v1.add("one");
v2.add("Two");
v3.add("Three");

System.out.println("Vector values are::" +v1);

for (count =0; count<=v1.size; count++)

{
if (v1.isEmpty() =! true && v1.size =! 0)
{

sarr = v1.toArray();
System.out.println("String array value is ::" +sarr);

s1 = sarr.toString();
System.out.println("String value are::" +s1);
}

}

}

}

when I tried to print the vector all the value is printing. But when I tried to print the string array its giving "[java.lang.string@16978b" as output. Probably its throwing the address of the particular value its keeping.

please suggest what to do.

[Campbell Ritchie]

. . . and have you read what it says in the Java Language Specification about what members an array has? Or the documentation for toString()? When you have read them, it should be obvious why you are getting that output.

[Ranganathan Kaliyur Mannar]

And please use Code Tags when posting java code.

[Prabhudatta Choudhury]

Campbell Ritchie wrote:. . . and have you read what it says in the Java Language Specification about what members an array has? Or the documentation for toString()? When you have read them, it should be obvious why you are getting that output.

Hi Ritchie,

I have a requirement of getting String values from a vector which contains String objects. When I tried to iterate that vector on vector size to get those values, its giving the address of the values instead of giving real values.

Please let me know how can I get the real value inside the String array. Please refer the code snapet I posted in my earlier post.

[Prabhudatta Choudhury]

Ranganathan Kaliyur Mannar wrote:And please use Code Tags when posting java code.

Hi Ranganathan,

Please find the code with tags below.

[CODE STARTS]

import java.util.*;
public class Test {

private static Vector v1 = new Vector();
private static String[] sarr = null;
private static String s1 = " ";
private static int count =0;

public static void main(String a[])
{

v1.add("one");
v2.add("Two");
v3.add("Three");

System.out.println("Vector values are::" +v1);

for (count =0; count<=v1.size; count++)

{
if (v1.isEmpty() =! true && v1.size =! 0)
{

sarr = v1.toArray();
System.out.println("String array value is ::" +sarr);

s1 = sarr.toString();
System.out.println("String value are::" +s1);
}

}

}

}


[CODE ENDS]

[Jesper de Jong]

Code tags do not look like [CODE STARTS] and [CODE ENDS], but like this:

[code]
... put your code here
[/code]

[Campbell Ritchie]

Jesper de Jong wrote:Code tags do not look like [CODE STARTS] and [CODE ENDS], but like this:

[code]
... put your code here

[/code]

Somebody has added code tags . . . but they don't work because they haven't indented the code.

[Campbell Ritchie]

I, earlier wrote:. . . and have you read what it says in the Java Language Specification about what members an array has? Or the documentation for toString()? When you have read them, it should be obvious why you are getting that output.

Have you read both those links?
And have you read about the Vector#toString() method?
I know what the answer to your problem is, but it will do you no good if I simply tell you. If you have read those links and not understood them, then we are only to happy to try to help you understand, but, as it says on the "Beginning Java" home page, we do not simply give out such answers.

[Prabhudatta Choudhury]

Campbell Ritchie wrote:

I, earlier wrote:. . . and have you read what it says in the Java Language Specification about what members an array has? Or the documentation for toString()? When you have read them, it should be obvious why you are getting that output.

Have you read both those links?
And have you read about the Vector#toString() method?
I know what the answer to your problem is, but it will do you no good if I simply tell you. If you have read those links and not understood them, then we are only to happy to try to help you understand, but, as it says on the "Beginning Java" home page, we do not simply give out such answers.

I already tried with toString() and toArray() method but none of my use.I even tried to iterate the vector and get those data to put into a string variable, but that also no of use.

[Rob Spoor]

What's wrong with toString()? And more importantly, how do you want the Vector to be turned into a String? As in, what should the String look like?

[Campbell Ritchie]

Rob is right to go on about toString().

Like most beginners, you have put lots of code in which you don't actually need. You can for example get rid of all the fields, and the loop which you don't need. When you get rid of the compiler errors too, you will actually see your Vector turned into a String. I am a bit surprised you hadn't noticed that earlier.
Why have you used Vector rather than ArrayList?
Why have you used a raw type, rather than giving the List an actual type parameter?

[Prabhudatta Choudhury]

Campbell Ritchie wrote:Rob is right to go on about toString().

Like most beginners, you have put lots of code in which you don't actually need. You can for example get rid of all the fields, and the loop which you don't need. When you get rid of the compiler errors too, you will actually see your Vector turned into a String. I am a bit surprised you hadn't noticed that earlier.
Why have you used Vector rather than ArrayList?
Why have you used a raw type, rather than giving the List an actual type parameter?

Ritchie,

I used Vector as I need my collection to be synchronized after some part. If I would have taken ArrayList, I had to convert that arraylist to synchronized one. In my Vector only Bigdecimals are there with alphabets as well.I want them to be in one String variable so that I can append them as and when I need to.

[Prabhudatta Choudhury]

Rob Spoor wrote:What's wrong with toString()? And more importantly, how do you want the Vector to be turned into a String? As in, what should the String look like?

Rob,

There is nothing wrong with toString(). But when I tried that it gave me "Type mismatch" error. That's why I tried to convert that vector to String araay and then String array to String. In my Vector only Bigdecimals are there with alphabets as well. I want them to be in one String variable so that I can append them as and when I need to.

[Campbell Ritchie]

Let's have another look at your initial code, copied and pasted without alteration

import java.util.*;
public class Test {

private static Vector v1 = new Vector();
private static String[] sarr = null;
private static String   s1 = " ";
private static int count =0;

public static void main(String a[])
{

v1.add("one");
v2.add("Two");
v3.add("Three");

System.out.println("Vector values are::" +v1);

for (count =0; count<=v1.size; count++)

{
if (v1.isEmpty() =! true && v1.size =! 0)
{

sarr = v1.toArray();
System.out.println("String array value is ::" +sarr);

s1 = sarr.toString();
System.out.println("String value are::" +s1);
}

}

}

}

Now, let's have the same code with indentation corrected

import java.util.*;
public class Test
{
    private static Vector v1 = new Vector();
    private static String[] sarr = null;
    private static String   s1 = " ";
    private static int count =0;

    public static void main(String a[])
    {
        v1.add("one");
        v2.add("Two");
        v3.add("Three");
        System.out.println("Vector values are::" +v1);

       for (count =0; count<=v1.size; count++)
       {
           if (v1.isEmpty() =! true && v1.size =! 0)
          {
              sarr = v1.toArray();
              System.out.println("String array value is ::" +sarr);
              s1 = sarr.toString();
              System.out.println("String value are::" +s1);
           }
       }
   }
}

Now we start commenting out code

import java.util.*;
public class Test
{
//    private static Vector v1 = new Vector();
//    private static String[] sarr = null;
//    private static String   s1 = " ";
//    private static int count =0;

    public static void main(String a[])
    {
        Vector v = new Vector();
        v.add("one");
        v.add("Two");
        v.add("Three");
        System.out.println("Vector values are::" +v1);

//       for (count =0; count<=v1.size; count++)
//       {
//           if (v1.isEmpty() =! true && v1.size =! 0)
//          {
//              sarr = v1.toArray();
//              System.out.println("String array value is ::" +sarr);
//              s1 = sarr.toString();
//              System.out.println("String value are::" +s1);
//           }
//       }
   }
}

You don't need the loop. You can loop through the entire Vector and append the values to a StringBuilder, if you prefer. What you are doing is repeatedly going through your Vector, turning it into an array, printing the array, and then repeating it.
That is, if your Vector isn't empty. But if the Vector were empty, you would never get to the test about isEmpty() because the loop won't start. Then you test whether its size (it should be size() not size) is 0, but you know it isn't 0 because you have just tested it isn't empty.
By the way, it isn't =!. It's !=
So you have got all this code which you don't actually need. If you delete enough code, you will get something which will actually compile. Try it. Note I have changed the Vector to be a local variable, and called it v.

If you declared it as List<String> and initialised it as Vector<String>, you can be sure it only takes Strings. Then you can fiddle the toArray method by passing it a String[]. You will have to look in the List interface because the hyperlink doesn't copy to our tags correctly.

import java.util.*;
public class Test
{
//    private static Vector v1 = new Vector();
//    private static String[] sarr = null;
//    private static String   s1 = " ";
//    private static int count =0;

    public static void main(String a[])
    {
        List<String> v = new Vector<String>();
        v.add("one");
        v.add("Two");
        v.add("Three");
        System.out.println("Vector values are::" +v1);
        System.out.print("Array: ");                   // new code
        System.out.println(v.toArray(new String[]{})); //new code

//       for (count =0; count<=v1.size; count++)
//       {
//           if (v1.isEmpty() =! true && v1.size =! 0)
//          {
//              sarr = v1.toArray();
//              System.out.println("String array value is ::" +sarr);
//              s1 = sarr.toString();
//              System.out.println("String value are::" +s1);
//           }
//       }
   }
}

The good news is, you have now got a String[] out of that for one line of code, rather than about 8 lines. If you want to use that String[] again, you will have to give it a name (identifier).
The bad news is, your String[] doesn't have an overridden toString() method. But I don't think you need that array at all. Look at the line of output above where it says[Ljava.lang.String@abdc1234.

Why are you trying to put BigDecimals and Strings into the same List? That sounds like suspect design to me.