Question

Consider the following program that creates an ArrayList of objects of a type A, and sorst them. Supply the missing code. Sample output when you run the program is shown below.

import java.util.*;

class A

{ int i, j, k;

public A(int i, int j, int k){

this.i=i;

this.j=j;

this.k=k;

}

public String toString(){

return "A("+i+","+j+","+k+")";

}

}

class SortA {

public static void main(String[] args){

ArrayList aL=new ArrayList();

Random rand= new Random(1000); //1000 is a seed value

for (int p=0; p<10; p++){

int i = rand.nextInt(100);

int j = rand.nextInt(200);

int k = rand.nextInt(300);

aL.add(new A(i, j, k));

}

System.out.println("----- Original arraylist------");

for (A a: aL){

System.out.println(a);

}

System.out.println("----- Sorting by first integer-------");

/*YOUR CODE - Use anonymous interface types to sort by first integer Field in A, and then print the resulting ArrayList */

System.out.println("----- Sorting by second integer-------");

/*YOUR CODE - Use anonymous interface types to sort by the second integer Field in A, and then print the resulting ArrayList */

System.out.println("----- Sorting by third integer-------"); /*YOUR CODE - Use anonymous interface types to sort by the third integer Field in A, and then print the resulting ArrayList */

} }

Output

----- Original list -------

A(87,135,276)

A(24,192,149)

A(41,45,164)

A(50,179,259)

A(72,183,36)

A(75,46,202)

A(23,41,222)

A(71,189,202)

A(93,142,49)

A(42,35,176)

----- Sorting by first integer-------

A(23,41,222)

A(24,192,149)

A(41,45,164)

A(42,35,176)

A(50,179,259)

A(71,189,202)

A(72,183,36)

A(75,46,202)

A(87,135,276)

A(93,142,49)

----- Sorting by second integer-------

A(42,35,176)

A(23,41,222)

A(41,45,164)

A(75,46,202)

A(87,135,276)

A(93,142,49)

A(50,179,259)

A(72,183,36)

A(71,189,202)

A(24,192,149)

----- Sorting by third integer-------

A(72,183,36)

A(93,142,49)

A(24,192,149)

A(41,45,164)

A(42,35,176)

A(75,46,202)

A(71,189,202)

A(23,41,222)

A(50,179,259)

A(87,135,276)

Answer 1

The code is

import java.util.*;

class A

{
int i, j, k;

public A(int i, int j, int k) {

this.i = i;

this.j = j;

this.k = k;

}

public String toString() {

return "A(" + i + "," + j + "," + k + ")";

}

}

public class SortA {

public static void main(String[] args) {

ArrayList<A> aL = new ArrayList<A>();

Random rand = new Random(1000); //1000 is a seed value

for (int p = 0; p < 10; p++) {

int i = rand.nextInt(100);

int j = rand.nextInt(200);

int k = rand.nextInt(300);

aL.add(new A(i, j, k));

}

System.out.println("----- Original arraylist------");

for (A a: aL) {

System.out.println(a);

}

System.out.println("----- Sorting by first integer-------");
Collections.sort(aL,new Comparator()
{

public int compare(Object o1, Object o2)
{
A sa = (A)o1;
A sb = (A)o2;
return sa.i-sb.i;   

// it can also return 0, and 1
}
});
for (A a: aL) {

System.out.println(a);

}

/*YOUR CODE - Use anonymous interface types to sort by first integer Field in A, and then print the resulting ArrayList */

System.out.println("----- Sorting by second integer-------");

/*YOUR CODE - Use anonymous interface types to sort by the second integer Field in A, and then print the resulting ArrayList */
Collections.sort(aL,new Comparator()
{

public int compare(Object o1, Object o2)
{
A sa = (A)o1;
A sb = (A)o2;
return sa.j-sb.j;   

// it can also return 0, and 1
}
});
for (A a: aL) {

System.out.println(a);

}
System.out.println("----- Sorting by third integer-------"); /*YOUR CODE - Use anonymous interface types to sort by the third integer Field in A, and then print the resulting ArrayList */
Collections.sort(aL,new Comparator()
{

public int compare(Object o1, Object o2)
{
A sa = (A)o1;
A sb = (A)o2;
return sa.k-sb.k;   

// it can also return 0, and 1
}
});
for (A a: aL) {

System.out.println(a);

}
}
}

The output is