OnJava8-Examples/arrays/ComparatorTest.java

// arrays/ComparatorTest.java
// <20>2015 MindView LLC: see Copyright.txt
// Implementing a Comparator for a class.
import java.util.*;
import com.mindviewinc.util.*;
import static com.mindviewinc.util.Print.*;

class CompTypeComparator implements Comparator<CompType> {
  public int compare(CompType o1, CompType o2) {
    return (o1.j < o2.j ? -1 : (o1.j == o2.j ? 0 : 1));
  }
}

public class ComparatorTest {
  public static void main(String[] args) {
    CompType[] a = Generated.array(
      new CompType[12], CompType.generator());
    print("before sorting:");
    print(Arrays.toString(a));
    Arrays.sort(a, new CompTypeComparator());
    print("after sorting:");
    print(Arrays.toString(a));
  }
}
/* Output:
before sorting:
[[i = 58, j = 55], [i = 93, j = 61], [i = 61, j = 29]
, [i = 68, j = 0], [i = 22, j = 7], [i = 88, j = 28]
, [i = 51, j = 89], [i = 9, j = 78], [i = 98, j = 61]
, [i = 20, j = 58], [i = 16, j = 40], [i = 11, j = 22]
]
after sorting:
[[i = 68, j = 0], [i = 22, j = 7], [i = 11, j = 22]
, [i = 88, j = 28], [i = 61, j = 29], [i = 16, j = 40]
, [i = 58, j = 55], [i = 20, j = 58], [i = 93, j = 61]
, [i = 98, j = 61], [i = 9, j = 78], [i = 51, j = 89]
]
*/