lambdaj框架使用示例，lambdaj框架示例,lambdaj框架使用示

lambdaj框架使用示例，lambdaj框架示例,lambdaj框架使用示

lambdaj框架使用示例

测试用Bean类：产品

package cn.outofmemory;/** * 测试用bean对象，产品 * @author 乔学士 * */public class Product {    private int id;    private String name;    private double price;    private double weight;    private String type;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public double getPrice() {        return price;    }    public void setPrice(double price) {        this.price = price;    }    public double getWeight() {        return weight;    }    public void setWeight(double weight) {        this.weight = weight;    }    public String getType() {        return type;    }    public void setType(String type) {        this.type = type;    }    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    @Override    public String toString() {        return "Product [id=" + id + ", name=" + name + ", price=" + price                + ", type=" + type + ", weight=" + weight + "]";    }}

生产产品的工厂

package info.yiwen.data;import java.util.ArrayList;import java.util.List;import java.util.Random;/** * 生产产品的工厂 * @author 乔学士 * */public class ProductFactory {    public static List<Product> genRandomProduct(int amount){        if(amount < 0 ){            amount = 1;        }        Random random = new Random();        List<Product> ps = new ArrayList<Product>(amount);        for(int i = 0; i < amount; i++){            Product p = new Product();            int randomNum = random.nextInt(100);             p.setId(i+1);            p.setId(i+1);            p.setName("name" + randomNum);            p.setPrice(Math.round(random.nextDouble() * 1000));            p.setWeight(Math.round(random.nextDouble() * 1000));            p.setType("type" + randomNum);            ps.add(p);        }        return ps;    }}

测试类

package info.yiwen.test;import java.util.Iterator;import java.util.List;import java.util.Map;import ch.lambdaj.function.closure.Closure;import info.yiwen.data.Product;import info.yiwen.data.ProductFactory;import static ch.lambdaj.Lambda.*;import static ch.lambdaj.collection.LambdaCollections.*;import static org.hamcrest.Matchers.*;/** * 测试类，方便起见，没有用jUnit * @author 乔学士 * */public class Test {    public static void main(String[] args) {        List<Product> ps = ProductFactory.genRandomProduct(10);        printl(1);        //1.简单例子        //对每个product都设置price为100        //forEach(ps).setPrice(100); //对每个product都设置setPrice为100        //按重量从小到大进行排序        ps = sort(ps, on(Product.class).getWeight());         print(ps);        printl(2);        //2.joinFrom 连接某个属性,中间默认用逗号加空格(", "), 可以自定义分隔符        //连接每个product对象的name        String names = joinFrom(ps).getName();        //连接每个product对象的name，间隔符为 ":"        String names2 = joinFrom(ps,":").getName();        System.out.println(names);        System.out.println(names2);        printl(3);        //3.select        //从ps中选择出重量大于等于500的        List<Product> ps2 = select(ps,                //注意下面greaterThanOrEqualTo方法中参数的类型一定要和getWeight严格相等                having(on(Product.class).getWeight(), greaterThanOrEqualTo(new Double(500)))        );        System.out.println(ps2);        printl(4);        //4.selectMin找到最小的, also selectMax        //找到重量最轻的产品        Product p = selectMin(ps, on(Product.class).getWeight());        System.out.println(p);        printl(5);        //5.max and maxFrom, also min and minFrom        //找到最重的产品的重量（两种方法）        //5.1        double weight1 = max(ps, on(Product.class).getWeight());        //5.2        double weight2 = maxFrom(ps).getWeight();        System.out.println(weight1 + "," + weight2);        printl(6);        //6.extract,抽取所有对象的某一列返回值        //得到每个产品的id        //6.1 使用on        List<Integer> ids = extract(ps, on(Product.class).getId());        System.out.println(ids);        //6.2 使用属性名        List<?> ids2 = extractProperty(ps, "id");        System.out.println(ids2);        printl(7);        //7.index 返回一个map，value是每个对象，key是对象的某个属性        //返回一个key为id，value是对象的Map        Map<Integer, ?> map = index(ps, on(Product.class).getId());         print(map);        printl(8);        //8.with 使用更为流畅的方法        //找到重量大于400的产品的id列表，并排序        //8.1原始方法        List<Double> prices1 = sort(                                extract(                                    select(ps, having(on(Product.class).getWeight(), greaterThan(400.0))),                                    on(Product.class).getPrice()                                ),                                 on(Double.class).doubleValue()                            );        //8.2使用with的方法        List<Double> prices2 = with(ps)                            .retain(having(on(Product.class).getWeight(), greaterThan(400.0)))                            .extract(on(Product.class).getPrice())                            .sort(on(Double.class).doubleValue());        System.out.println(prices1);        System.out.println(prices2);        printl(9);        //9.闭包 ，of(T t) 返回T类型        Closure println = closure(); //创建一个closure，放到ThreadLocal中        of(System.out).println(var(String.class)); //of方法从ThreadLocal中得到这个Closure        println.apply("hello");        println.each("hello","oschina");    }    static void print(Iterable<?> ps){        Iterator<?> it = ps.iterator();        while(it.hasNext()){            System.out.println(it.next());        }    }    static void print(Map<?, ?> map){        for(Map.Entry<?, ?> e :map.entrySet()){            System.out.println(e.getKey() + ":" + e.getValue());        }    }    static void printl(int itemNo){        System.out.println("--------------------" + itemNo + "---------------------");    }}

结果

--------------------1---------------------Product [id=4, name=name22, price=56.0, type=type22, weight=193.0]Product [id=6, name=name24, price=35.0, type=type24, weight=194.0]Product [id=9, name=name48, price=371.0, type=type48, weight=417.0]Product [id=8, name=name95, price=981.0, type=type95, weight=434.0]Product [id=5, name=name22, price=566.0, type=type22, weight=594.0]Product [id=2, name=name83, price=249.0, type=type83, weight=764.0]Product [id=10, name=name17, price=359.0, type=type17, weight=855.0]Product [id=7, name=name30, price=203.0, type=type30, weight=877.0]Product [id=3, name=name94, price=897.0, type=type94, weight=981.0]Product [id=1, name=name55, price=714.0, type=type55, weight=991.0]--------------------2---------------------name22, name24, name48, name95, name22, name83, name17, name30, name94, name55name22:name24:name48:name95:name22:name83:name17:name30:name94:name55--------------------3---------------------[Product [id=5, name=name22, price=566.0, type=type22, weight=594.0], Product [id=2, name=name83, price=249.0, type=type83, weight=764.0], Product [id=10, name=name17, price=359.0, type=type17, weight=855.0], Product [id=7, name=name30, price=203.0, type=type30, weight=877.0], Product [id=3, name=name94, price=897.0, type=type94, weight=981.0], Product [id=1, name=name55, price=714.0, type=type55, weight=991.0]]--------------------4---------------------Product [id=4, name=name22, price=56.0, type=type22, weight=193.0]--------------------5---------------------991.0,991.0--------------------6---------------------[4, 6, 9, 8, 5, 2, 10, 7, 3, 1][4, 6, 9, 8, 5, 2, 10, 7, 3, 1]--------------------7---------------------1:Product [id=1, name=name55, price=714.0, type=type55, weight=991.0]2:Product [id=2, name=name83, price=249.0, type=type83, weight=764.0]3:Product [id=3, name=name94, price=897.0, type=type94, weight=981.0]4:Product [id=4, name=name22, price=56.0, type=type22, weight=193.0]5:Product [id=5, name=name22, price=566.0, type=type22, weight=594.0]6:Product [id=6, name=name24, price=35.0, type=type24, weight=194.0]7:Product [id=7, name=name30, price=203.0, type=type30, weight=877.0]8:Product [id=8, name=name95, price=981.0, type=type95, weight=434.0]9:Product [id=9, name=name48, price=371.0, type=type48, weight=417.0]10:Product [id=10, name=name17, price=359.0, type=type17, weight=855.0]--------------------8---------------------[203.0, 249.0, 359.0, 371.0, 566.0, 714.0, 897.0, 981.0][203.0, 249.0, 359.0, 371.0, 566.0, 714.0, 897.0, 981.0]--------------------9---------------------hellohellooschina