### JAVA8 方法引用  ``` // 方法一：传递代码 public class AppleComparator implements Comparator<Apple> { public int compare(Apple a1, Apple a2){ return a1.getWeight().compareTo(a2.getWeight()); } } inventory.sort(new AppleComparator()); // 方法二：实用匿名类 inventory.sort(new Comparator<Apple>() { public int compare(Apple a1, Apple a2){ return a1.getWeight().compareTo(a2.getWeight()); } }); // 方法三：实用lambda表达式 inventory.sort((Apple a1, Apple a2) -> a1.getWeight().compareTo(a2.getWeight()) ); inventory.sort((a1, a2) -> a1.getWeight().compareTo(a2.getWeight())); // 方法四：实用方法引用 inventory.sort(comparing(Apple::getWeight)); // java.util.Comparator.comparing ```