Making a concat operator to add char array to a string. Printing a reference variable of a string object

Question

So far, if I try to use the concat operator I get this error Tester.java:14: cannot find symbol symbol : method concat(MyString) location: class MyString System.out.println(hello.concat(goodbye)); // prints "hellogoodbye"

and when I try to print the "hello" object of MyString I get MyString@558ee9d6 I feel like its soo close to working..

public class MyString

{
     private char[] charString;
     private String oneString;


      public  MyString(String string) 
      {
        this.oneString = string;


      }

//second constructor for overloading
    public MyString(char[] s) 
    {

        this.charString = s;
        this.oneString = charString.toString();
    }

//methods
    public String toString( char [] s)
    {
        return new String(s);
    }

    public char charAt(int i) {

        char [] temp = new char[oneString.length()];
        for ( int j = 0; j < oneString.length() ;  j++)
        temp[j] = oneString.charAt(i);
        return temp[i];
    }

    public String concat ( char[] s)
    {
        s.toString();
        String result = oneString + s;
        return result;
    }

    public String concat ( String s)
    {
        String result = oneString + s;
        return result;
    }


}

public class Tester { public static void main (String[] args)

    {
    MyString hello = new MyString("hello");
    System.out.println(hello);  // right now this prints MyString@558ee9d6
    System.out.println(hello.charAt(0));    // works, prints 'h'
    char[] arr = {'g','o','o','d','b','y','e' };
    MyString goodbye = new MyString(arr);
   // System.out.println(hello.concat(goodbye)); // i can't get this line to work
    System.out.println(hello.equals(goodbye)); // works, prints false
    System.out.println(hello.equals(hello));  //works, prints true
    }
    }

You should probably proofread your code a little bit before posting it. There are a lot of problems that a simple compile could help you with. — Shawn Shroyer
– Shawn Shroyer, Commented Nov 14, 2012 at 1:51
The internal charString is that required? It's just complicating your internal state, keeping just a String makes it much simpler. — zapl
– zapl, Commented Nov 14, 2012 at 1:51

dreamcrash · Accepted Answer · 2012-11-14 01:49:05Z

You are trying to print an Object :

System.out.println(hello);  // right now this prints MyString@558ee9d6

In this case your MyString class

Make the get method to your variable oneString.

public String getOneString() {return this.oneString;}

and then call

System.out.println(hello.getOneString());

Another problem

System.out.println(hello.concat(goodbye));

You concat method receives a string and not a MyString class

You may want to do this

System.out.println(hello.concat(goodbye.getOneString()));

or

public String concat ( MyString myS)
    {
        String s = myS.getOneString();
        String result = oneString + s;
        return result;
    }

Final result:

public class Tester { public static void main (String[] args)

    {
    MyString hello = new MyString("hello");
    System.out.println(hello.getOneString());
    System.out.println(hello.getOneString().charAt(0)); 
    char[] arr = {'g','o','o','d','b','y','e' };
    MyString goodbye = new MyString(arr);
    System.out.println(hello.concat(goodbye.getOneString()));
    System.out.println(hello.equals(goodbye)); // works, prints false
    System.out.println(hello.equals(hello));  //works, prints true
    }
    }

Luiggi Mendoza · Accepted Answer · 2012-11-14 01:43:45Z

1

charString.toString() will give you the String representation of the char[] object, it won't convert your char[] into a String.

If you want/need that oneString attribute contains the String representation of your charString, then you could create a String using your char array:

this.oneString = new String(charString);

Also, this line

System.out.println(hello);

would print the String representation of your object. You need to override the public String toString() method in Object class in your MyString class:

@Override
public String toString() {
    return this.oneString; //or similar
}

answered Nov 14, 2012 at 1:43

Luiggi Mendoza

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2 Comments

Fred V Over a year ago

do you know why does do i get a "cannot find symbol" error for concat when i try to run it?

Luiggi Mendoza Over a year ago

@FredV that's because your concat method receives a char[] or a String parameter, not a MyString, and you have MyString goodbye.

Shawn Shroyer · Accepted Answer · 2012-11-14 01:48:37Z

0

I would say that right now, you are trying to add a character array to a string. Calling s.toString() wouldn't make the char[] a String. That won't work the way you have it. Try

result = oneString + new String(s);

answered Nov 14, 2012 at 1:48

Shawn Shroyer

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