サンプル
* Enumを逆順でソートさせる(もっとスマートにやりたいが)
SignalType
* Enum
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public enum SignalType {
None(-2),
Red(-1),
Yellow(0),
Green(1);
public static final int DESCENDENT = -1;
private int value;
private SignalType(int value) {
this.value = value;
}
public int getValue() {
return this.value;
}
/** ★ここがポイント. */
public static void sort(List<SignalType> list) {
Collections.sort(list, new Comparator<SignalType>() {
@Override
public int compare(SignalType source, SignalType distination) {
int sortOrderOfSource = source.ordinal();
int sortOrderOfDistination = distination.ordinal();
int returnValue;
if (sortOrderOfSource > sortOrderOfDistination) {
returnValue = 1;
} else if (sortOrderOfSource == sortOrderOfDistination) {
returnValue = 0;
} else {
returnValue = -1;
}
return returnValue * DESCENDENT;
}
});
}
}
* 呼び出し側
import java.util.ArrayList;
import java.util.List;
public class Main {
public static void main(String[] args) {
List<SignalType> list = new ArrayList<SignalType>() {
private static final long serialVersionUID = 1L;
{
add(SignalType.Red);
add(SignalType.Green);
add(SignalType.Yellow);
}
};
System.out.println("Before sorting");
for (SignalType type : list) {
System.out.println(type);
}
System.out.println();
System.out.println("After sorting");
SignalType.sort(list);
for (SignalType type : list) {
System.out.println(type);
}
}
}
出力結果
Before sorting
Red
Green
Yellow
After sorting
Green
Yellow
Red
