I use such a mechanism in my application: get random string from string array and put it in the SQLite database. Then I send this new string to the widget and to ArrayList for ListActivity representation. Before the putting new object to the database I need to check if it is no object with the same text field value. My Quote object:
public class Quote {
private String text;
private String date;
public Quote(String text, String date)
{
this.text = text;
this.date = date;
}
public Quote(){}
public String getText()
{return this.text;}
public String getDate()
{return this.date;}
public void setText(String text)
{
this.text = text;
}
public void setDate(String date)
{
this.date = date;
}
@Override
public String toString() {
return text + "" + date;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
final Quote other = (Quote) obj;
if (text.equalsIgnoreCase(other.text))
return false;
return true;
}
@Override
public int hashCode() {
int hash = 7;
hash = 89 * hash + (this.text != null ? this.text.hashCode() : 0);
hash = 89 * hash + (this.date != null ? this.date.hashCode() : 0);
return hash;
}
}
and this is how I get my random string with checking mechanism:
private String getRandomString(Context context)
{
String l = "";
String[] a = context.getResources().getStringArray(R.array.quotes);
l = a[rgenerator.nextInt(a.length)];
Quote quote = new Quote(l,mydate);
ArrayList<Quote> intermediate = getQuotes(context);
if (intermediate.contains(quote))
l=getRandomString(context);
return l;
}
but when I do it like this, I've got StackOverflowError. How can I solve it?
I solved this by Singletone pattern using.
public class StringSingletone {
static int i;
String []a;
private static StringSingletone instance;
LinkedList<String> quotes ;
// Private constructor prevents instantiation from other classes
private StringSingletone(Context context) {
a = context.getResources().getStringArray(R.array.quotes);
quotes = new LinkedList<String>(Arrays.asList(a));
Collections.shuffle(quotes);
}
/**
* SingletonHolder is loaded on the first execution of Singleton.getInstance()
* or the first access to SingletonHolder.INSTANCE, not before.
*/
public static StringSingletone getInstance() {
return instance;
}
public static void initInstance(Context context)
{
if (instance == null)
{
// Create the instance
instance = new StringSingletone(context);
}
}
private void remakeObj(Context context)
{
a = context.getResources().getStringArray(R.array.quotes);
quotes = new LinkedList<String>(Arrays.asList(a));
Collections.shuffle(quotes);
}
public String getRandomString(Context context)
{
if (quotes.size()==0)
{
remakeObj( context);
}
String l = quotes.pop();
return l;
}
}