How to sort an array of objects?

Question

I need to sort an array of objects. Each object has serial number, and other properties. I need to sort it by serial number.

Answer 1

Do a java.util.Arrays.sort(). The method has quite a few overloads, so I'll give a complete example this time:import java.util.*
public class SortDemo {
    public static void main(String args) {
        SimpleObject[] objs = new SimpleObject[10];
        for (int i=0; i<10; i++)
            objs=new SimpleObject();
dump(objs);
Comparator c = new SimpleComparator();
Arrays.sort(objs, c);
dump(objs);
static void dump(Object[] o) {
for (int i=0; i<o.length; i++)
System.out.print(o[i] + " ");
/** Object to demonstrate comparing with **/
class SimpleObject {
private int n = (int) (10*Math.random());
public String toString() {
return String.valueOf(getNumber());
public int getNumber() {return n;}
/** The custom comparator **/
class SimpleComparator implements Comparator {
public int compare(Object o1, Object o2) {
return ((SimpleObject) o1).getNumber() - ((SimpleObject) o2).getNumber();
public boolean equals(Object o) {return false;}
}I could have made the SimpleObject class "Comparable", but a design like this allows more flexibility so I decided to use another class for the Comparator.