使用谓词(Predicate)传递方法为参数，且通过Lambda表达式时间最简洁写法

//定义一个apple类
public class Apple {

    public Apple(int welght, String color) {
        this.color = color;
        this.welght = welght;
    }

    private int welght;
    private String color;

    public int getWelght() {
        return welght;
    }

    public void setWelght(int welght) {
        this.welght = welght;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }
}

class TestDemo {
    /**
     * @param inventory 库存
     * @return 颜色为绿色的所有苹果
     */
    public static List<Apple> filterGreenApples(List<Apple> inventory) {
        List<Apple> result = new ArrayList<>();
        for (Apple apple : inventory) {
            if ("green".equals(apple.getColor())) {
                result.add(apple);
            }
        }
        return result;
    }

    //重量大于150的所有苹果
    public static List<Apple> filterHeavyApples(List<Apple> inventory) {
        List<Apple> result = new ArrayList<>();
        for (Apple apple : inventory) {
            if (apple.getWelght() > 150) {
                result.add(apple);
            }
        }
        return result;
    }

　　//以上查找苹果的2个方法 只有判断苹果条件（颜色、重量）这句代码不同，其他代码一致
   //下面将这些条件作为参数传递给方法，统一代码书写方式

    public static boolean isGreenApple(Apple apple) {
        return "green".equals(apple.getColor());
    }

    public static boolean isHeavyApple(Apple apple) {
        return apple.getWelght() > 150;
    }

    public interface Predicate<T> {
        boolean test(T t);
    }

    static List<Apple> filterApples(List<Apple> inventory, Predicate<Apple> p) {
        List<Apple> result = new ArrayList<>();
        for (Apple apple : inventory) {
            //apple是否符合条件
            if (p.test(apple)) {
                result.add(apple);
            }
        }
        return result;
    }

    static void main(String[] args) {
        List<Apple> appleList = new ArrayList<>();
        //Apple::isGreenApple 接受参数Apple并返回一个boolean
        //filterApples(appleList, Apple::isGreenApple);
        //最简洁filterApples（List<Apple> inventory,Predicate<Apple> p）的写法
        filterApples(appleList, (Apple a) -> "green".equals(a.getColor()));
        filterApples(appleList, (Apple a) -> a.getWelght() > 150 || "brown".equals(a.getColor()));
    }