JDK 1.5 特性使用实例3－－AutoBoxing

package maoxiang.examples.jdk15;

import java.util.AbstractList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

/**
* @author 毛翔
*
* box 将primitive 类型转换成复合对象 ，如将int 转换成Integer
* unbox 将复合对象转换成primitive Integer.intValue()
*/
public class AutoBoxing {

public static void main(String[] args) {
AutoBoxing test = new AutoBoxing();
test.Test1();
}

public void Test1() {
String[] args = new String[] { "1", "2", "3", "4", "5", "6", "7", "8" };
Map<String, Integer> m = new TreeMap<String, Integer>();
for (String word : args) {
Integer freq = m.get(word);
m.put(word, (freq == null ? 1 : freq + 1));
}
System.out.println(m);

}

// List adapter for primitive int array
public static List<Integer> asList(final int[] a) {
return new AbstractList<Integer>() {
public Integer get(int i) {
return a[i];
}

// Throws NullPointerException if val == null
public Integer set(int i, Integer val) {
Integer oldVal = a[i];
a[i] = val;
return oldVal;
}

public int size() {
return a.length;
}
};
}

}