Mega Code Archive
Utilities for generic ArrayList
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import java.awt.Polygon;
import java.awt.Rectangle;
import java.awt.Shape;
import java.util.ArrayList;
import java.util.GregorianCalendar;
public class UtilsTester {
public static void main(String[] args) throws InstantiationException,
IllegalAccessException {
ArrayList<String> ids = new ArrayList<String>();
Utils.fill(ids, "default", 10);
System.out.println(ids);
ArrayList<Shape> shapes = new ArrayList<Shape>();
Utils.fill(shapes, new Rectangle(5, 10, 20, 30), 2);
System.out.println(shapes);
ArrayList<Polygon> polys = new ArrayList<Polygon>();
Utils.fillWithDefaults(polys, Polygon.class, 10);
Utils.append(shapes, polys, 2);
System.out.println(shapes);
ArrayList<GregorianCalendar> dates = new ArrayList<GregorianCalendar>();
Utils.fillWithDefaults(dates, GregorianCalendar.class, 5);
System.out.println(Utils.getMax(dates));
}
}
class Utils {
public static <E> void fill(ArrayList<E> a, E value, int count) {
for (int i = 0; i < count; i++)
a.add(value);
}
public static <E, F extends E> void append(ArrayList<E> a, ArrayList<F> b,
int count) {
for (int i = 0; i < count && i < b.size(); i++)
a.add(b.get(i));
}
public static <E extends Comparable<? super E>> E getMax(ArrayList<E> a) {
E max = a.get(0);
for (int i = 1; i < a.size(); i++)
if (a.get(i).compareTo(max) > 0)
max = a.get(i);
return max;
}
public static <E> void fillWithDefaults(ArrayList<E> a,
Class<? extends E> cl, int count) throws InstantiationException,
IllegalAccessException {
for (int i = 0; i < count; i++)
a.add(cl.newInstance());
}
}
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