Simple to use Java Lambda filter foreach of

Simple to use Java Lambda filter foreach of

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List of Java in the collection by the time the query conditions, often think of using for loop.

Since the introduction of Java 8 Lambda, simplifies the use of the loop.

Lambda illustrates a simple use of the foreach and filter.

 

1, custom class Hero

/**
 * Created by Miracle Luna on 2020/3/8
 */
public class Hero {
    private String name;
    private String country;

    public Hero(String name, String country) {
        this.name = name;
        this.country = country;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    @Override
    public String toString() {
        return "Hero{" +
                "name='" + name + '\'' +
                ", country='" + country + '\'' +
                '}';
    }
}

 

2, foreach loop

import java.util.ArrayList;
import java.util.List;

/**
 * Created by Miracle Luna on 2020/3/8
 */
public class LambdaForeachDemo {
    public static void main(String[] args) {
        List<Hero> heroList = new ArrayList<>();
        List<Hero> resultList = new ArrayList<>();

        Hero liubei = new Hero("刘备", "蜀国");
        Hero guanyu = new Hero("关羽", "蜀国");=
        Zhangfei Heronew new Hero ( "Zhang", "Shu" ); 
        Hero Sunce = new new Hero ( "Sun Ce", "Wu" ); 

        heroList.add (liubei); 
        heroList.add (Guanyu); 
        heroList.add (Zhangfei) ; 
        heroList.add (Sunce); 

        // query is not a hero Wu 
        heroList.forEach (hero -> {
             IF ( "Wu"! .equals (hero.getCountry ())) { 
                resultList.add (hero); 
            } 
        }); 

        // print the results set 
        resultList.forEach (Hero -> System.out.println (hero.toString ())); 
    } 
}

 

3, filter filter

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

/**
 * Created by Miracle Luna on 2020/3/8
 */
public class LambdaFilterDemo {
    public static void main(String[] args) {
        List<Hero> heroList = new ArrayList<>();
        List<Hero> resultList = new ArrayList<>();

        Hero liubei = new Hero("刘备", "蜀国");
        Hero guanyu = new Hero("关羽", "蜀国");
        Zhangfei Hero = new new Hero ( "Zhang", "Shu" ); 
        Hero Sunce = new new Hero ( "Sun Ce", "Wu" ); 

        heroList.add (liubei); 
        heroList.add (Guanyu); 
        heroList.add (Zhangfei); 
        heroList.add (Sunce); 

        // query is not a hero Wu 
        resultList = heroList.stream () 
                (hero .filter ! -> "Wu" .equals (hero.getCountry ())) 
                .collect ( Collectors.toList ()); 

        // print the results set 
        resultList.forEach (Hero -> System.out.println (hero.toString ())); 
    } 
}

 

4, the results are as follows:

Hero {name = 'Bei', country = 'Shu' } 
Hero {name = 'Guan', country = 'Shu' } 
Hero {name = 'Zhang', country = 'Shu'}