第一个java8 lambda表达式例子

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public class Test {
    public static <T> List<T> filter(List<T> list, Predicate<T> p){
        List<T> result = new ArrayList<T>();
        for(T e: list){
            if(p.test(e)){
                result.add(e);
            }
        }
        return result;
    }

    public static void main(String[] args) {
        List<Apple> inventory = new ArrayList<Apple>();
        inventory.add(new Apple("red",155));
        inventory.add(new Apple("green",100));
        List<Apple> redApples =
                filter(inventory, (Apple apple) -> "red".equals(apple.getColor()));
//        List<Integer> evenNumbers =
//                filter(numbers, (Integer i) -> i % 2 == 0);
    }

}

public class Apple {
    private String color;
    private Integer weight;


    public Apple(String color,Integer weight){
        this.color = color;
        this.weight = weight;
    }

    public String getColor() {
        return color;
    }

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

    public Integer getWeight() {
        return weight;
    }

    public void setWeight(Integer weight) {
        this.weight = weight;
    }
}

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

如果idea报错：

lambda expressions are not supported at this language level

那么解决方式：