Java 6のNavigableSetとNavigableMapを使用する方法
最新のJava 6のコレクションAPIを使用して、セットをナビゲートしてコレクションをマップできます。 これらのAPIは、コレクションから必要な結果を見つけるための柔軟性を提供します。
1. NavigableMapの例
package com.example.collection;
import java.util.NavigableMap;
import java.util.TreeMap;
public class NavigableMapDemo {
public static void main(String[] args) {
NavigableMap navigableMap=new TreeMap();
navigableMap.put("X", 500);
navigableMap.put("B", 600);
navigableMap.put("A", 700);
navigableMap.put("T", 800);
navigableMap.put("Y", 900);
navigableMap.put("Z", 200);
System.out.printf("Descending Set : %s%n",navigableMap.descendingKeySet());
System.out.printf("Floor Entry : %s%n",navigableMap.floorEntry("L"));
System.out.printf("First Entry : %s%n",navigableMap.firstEntry());
System.out.printf("Last Key : %s%n",navigableMap.lastKey());
System.out.printf("First Key : %s%n",navigableMap.firstKey());
System.out.printf("Original Map : %s%n",navigableMap);
System.out.printf("Reverse Map : %s%n",navigableMap.descendingMap());
}
}
出力
Descending Set : [Z, Y, X, T, B, A]
Floor Entry : B=600
First Entry : A=700
Last Key : Z
First Key : A
Original Map : {A=700, B=600, T=800, X=500, Y=900, Z=200}
Reverse Map : {Z=200, Y=900, X=500, T=800, B=600, A=700}
2. NavigableSetの例
package com.example.collection;
import java.util.Arrays;
import java.util.Iterator;
import java.util.NavigableSet;
import java.util.TreeSet;
public class NavigableSetDemo {
public static void main(String[] args) {
NavigableSet navigableSet = new TreeSet(Arrays.asList(
"X", "B", "A", "Z", "T"));
Iterator iterator = navigableSet.descendingIterator();
System.out.println("Original Set :");
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
iterator = navigableSet.iterator();
System.out.println("Sorted Navigable Set :");
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
System.out.printf("Head Set : %s.%n", navigableSet.headSet("X"));
System.out.printf("Tail Set : %s.%n", navigableSet.tailSet("T", false));
System.out.printf("Sub Set : %s.%n",
navigableSet.subSet("B", true, "X", true));
System.out.printf("Last Element : %s%n", navigableSet.last());
System.out.printf("First Element : %s%n", navigableSet.first());
System.out.printf("Reverse Set : %s%n", navigableSet.descendingSet());
System.out.printf("Original Set : %s%n", navigableSet);
}
}
出力
Original Set : Z X T B A Sorted Navigable Set : A B T X Z Head Set : [A, B, T]. Tail Set : [X, Z]. Sub Set : [B, T, X]. Last Element : Z First Element : A Reverse Set : [Z, X, T, B, A] Original Set : [A, B, T, X, Z]
ソースコードをダウンロード
ダウンロード–Navigable-Collection-Example.zip（1kb）