// string Comparable example

import java.util.*;


class String implements Comparable {

    ...

    public int compareTo( Object obj ) {

	String other = (String) obj;

	// Search for a differing character

	int i;
	for (i=0; i<this.length() && i<other.length(); i++)
	    if (this.charAt(i) != other.charAt(i))
		break;

	if (i == this.length() && i == other.length())
	    return 0;		// none found; both end at same place

	else if (i == this.length())
	    return -1;		// this ends first with no differences

	else if (i == other.length())
	    return +1;		// other ends first with no differences

	else			// difference found at position i
	    return (this.charAt(i) - other.charAt(i));
    }

    ...
}