// interface Sortable -- makes an array of objects sortable by providing
// a function that can compare them, assuming that compare returns:
// a negative number if invoking obj < parm
// 0 if invoking obj == parm
// a positive number if invoking obj > parm
public interface Sortable {
public int compare(Sortable other);
}
// class Sort -- a class containing static sorting methods that can
// sort any array of Sortable objects
public class Sort {
// selection sort function
static void selection_sort(Sortable[] values) {
int minloc;
Sortable temp;
int size = values.length;
for (int j = 0 ; j < size - 1 ; j++) {
minloc = j;
for (int k = j + 1 ; k < size ; k++)
if (values[k].compare(values[minloc]) < 0)
minloc = k;
if (minloc != j) {
temp = values[minloc];
values[minloc] = values[j];
values[j] = temp;
}
}
}
// we could add other sorting methods here
} // end class Sort
// class IntNum -- a class for Sortable ints
public class IntNum implements Sortable {
private int theNum; // field to hold the integer
public IntNum() {
theNum = 0;
}
public IntNum(int number) {
theNum = number;
}
// compare function required by Sortable interface
public int compare(Sortable another) {
return ((IntNum)this).theNum - ((IntNum) another).theNum;
}
// allows us to print an IntNum
public String toString() {
return Integer.toString(theNum);
}
} // end class IntNum
// class Employee -- a class for Employees
public class Employee implements Sortable {
private int SSNum; // the social security number
private String firstname;
private String lastname;
private int salary;
public Employee() { }
public Employee(int SSN, String first, String last, int sal) {
SSNum = SSN;
firstname = first;
lastname = last;
salary = sal;
}
// compare function required by Sortable interface
// orders Employees by social security number
public int compare(Sortable another) {
return ((Employee)this).SSNum - ((Employee) another).SSNum;
}
// allows us to print an Employee
public String toString() {
String emp;
emp = Integer.toString(SSNum) + " " + lastname + " "
+ firstname + " " + Integer.toString(salary);
return emp;
}
} // end class Employee
// class to show use of Sortable interface
public class SortTest {
public static void main(String[] args) {
// create an array of IntNums, print them, sort them, and print them again
IntNum[] nums = new IntNum[5];
nums[0] = new IntNum(8);
nums[1] = new IntNum(3);
nums[2] = new IntNum(6);
nums[3] = new IntNum(1);
nums[4] = new IntNum(5);
System.out.println("Values before sorting:");
for (int i = 0 ; i < nums.length ; i++)
System.out.println(nums[i]);
Sort.selection_sort(nums);
System.out.println("Values after sorting:");
for (int i = 0 ; i < nums.length ; i++)
System.out.println(nums[i]);
// create an array of Employees, print them, sort them, and print them again
Employee[] people = new Employee[4];
people[0] = new Employee(444556666,"Shiva","Chaudhuri",75000);
people[1] = new Employee(222334444,"Rosie","Rubel ",64000);
people[2] = new Employee(888776666,"Sofia","Palacios ",67000);
people[3] = new Employee(555667777,"Seham","Gorab ",84000);
System.out.println("Values before sorting:");
for (int i = 0 ; i < people.length ; i++)
System.out.println(people[i]);
Sort.selection_sort(people);
System.out.println("Values after sorting:");
for (int i = 0 ; i < people.length ; i++)
System.out.println(people[i]);
}
} // end class SortTest
Values before sorting: 8 3 6 1 5 Values after sorting: 1 3 5 6 8 Values before sorting: 444556666 Chaudhuri Shiva 75000 222334444 Rubel Rosie 64000 888776666 Palacios Sofia 67000 555667777 Gorab Seham 84000 Values after sorting: 222334444 Rubel Rosie 64000 444556666 Chaudhuri Shiva 75000 555667777 Gorab Seham 84000 888776666 Palacios Sofia 67000