import static com.google.common.base.Preconditions.checkNotNull;

import java.util.Collection;

import com.google.common.collect.Lists;

/**
 * Math工具類
 * 
 * @version 1.0
 * @since 1.0
 */
public class MathUtil {

 /**
  * @see MathUtil#min(Collection)
  * @param ts
  * @return
  */
 public static <T extends Comparable<T>> T min(T... ts) {
  return min(Lists.newArrayList(ts));
 }

 /**
  * 取最小值
  * @param values
  * @throws NullPointerException if (values == null || values.contain(null))
  * @return
  */
 public static <T extends Comparable<T>> T min(Collection<T> values) {
  checkNotNull(values);
  T min = null;

  for (T t : values) {
   checkNotNull(t);
   if (min == null) {
    min = t;
   } else {
    min = min.compareTo(t) < 0 ? min : t;
   }
  }
  return min;
 }

 /**
  * @see MathUtil#max(Collection)
  * @param ts
  * @return
  */
 public static <T extends Comparable<T>> T max(T... ts) {
  return max(Lists.newArrayList(ts));
 }

 /**
  * 取最大值
  * @param values
  * @throws NullPointerException if (values == null || values.contain(null))
  * @return
  */
 public static <T extends Comparable<T>> T max(Collection<T> values) {
  checkNotNull(values);
  T max = null;

  for (T t : values) {
   checkNotNull(t);
   if (max == null) {
    max = t;
   } else {
    max = max.compareTo(t) > 0 ? max : t;
   }
  }
  return max;
 }

 /**
  * 求和
  * @param values
  * @throws NullPointerException if (values == null || values.contain(null))
  * @return
  */
 public static Integer sum(Collection<Integer> values) {
  checkNotNull(values);
  int sum = 0;
  for (Integer integer : values) {
   checkNotNull(integer);
   sum += integer;
  }
  return sum;
 }

 /**
  * @see MathUtil#sum(Collection)
  * @param ts
  * @return
  */
 public static Integer sum(Integer... ts) {
  return sum(Lists.newArrayList(ts));
 }

}