if statement comparing strings in java android [duplicate]

Question

Possible Duplicate:
Java String.equals versus ==

I'm trying to write a method in az DBOpenHelper extends SQLOpenHelper class. It supposed to evaluate if there's an entry in the DB with the same name.

public boolean existsContact(Contact contact) {

    SQLiteDatabase db = this.getReadableDatabase();
    String selectQuery = "SELECT  * FROM " + TABLE_CONTACTS;
    Cursor cursor = db.rawQuery(selectQuery, null);
    if (cursor.moveToFirst()) {
        do {

            String name = cursor.getString(1);
            String cname = contact.getName();
            if (name == cname) {

                cursor.close();
                db.close();
                return true;
            }

        } while (cursor.moveToNext());
    }

    db.close();

    return false;
}

Here's the relevant part of Contact class:

 public class Contact {

    String _name;
    public String getName(){
        return this._name;
    }
    }

Now here's the strange thing:

Scenario A : if (name == cname) where name = "foo" and cname = "foo" equals false. Eclipse debugger show name's foo and cname's foo have different id's. both variables filled as seen before in code.

Scenario B: if(name == cname) where variabales are loaded like this:

String name = "foo";
String cname = "foo";
         statement equals true as it's supposed to.

Scenario C: if("foo" == "foo") equals true...BUT...debugger goes out the window. LogCat show debugger connected, but there's no activity in eclipse's Debug perspective. Breakpoints have no effect. No Threads shown.

Answer 1

In java, when using == on two objects, you're not actually comparing the strings themselves. You'll need to use .equals(String).

== actually compares the two object's references, not their values.

string1.equals(String target) compares the two strings based off of the actual characters in the strings.

See: http://www.leepoint.net/notes-java/data/expressions/22compareobjects.html

Answer 2

== operator check object reference are equal or not but equals() method check values are same or not

    if (name == cname) 
   {    
    cursor.close();
    db.close();
    return true;
  }

change with it

 if (name.equals(cname)){        
    cursor.close();
    db.close();
   return true;
}