【Java】两个 List 遍历匹配数据的优化处理

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首先，举个例子：例如有一个List<Student>，另外一个是List<Husband>，你现在要筛选出来自同一个家庭的丈夫和妻子，组成一个家庭的数据全集（一个家庭包含丈夫、妻子），这样就是吧数据赋值给另外一个List<Family>（这个例子可能不恰当，欢迎评论给出更好的例子）;

说明：代码采用java8的Stream和Lambda处理List，如果对Stream和Lambda不太了解的，先查阅另外一篇文章：http://blog.csdn.net/qi_lin7/article/details/52958123

好吧，大家还是结合代码来看吧

Wife.java

import java.io.Serializable;

/**
 * Author: 
 * Date: 2016/11/23.
 * Time: 18:08
 */
public class Wife implements Serializable {
    private int id;
    /**妻子名字**/
    private String wifeName;
    /**家庭ID**/
    private String familyId;

    public Wife() {

    }

    public Wife(int id, String wifeName, String familyId) {
        this.id = id;
        this.wifeName = wifeName;
        this.familyId = familyId;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getWifeName() {
        return wifeName;
    }

    public void setWifeName(String wifeName) {
        this.wifeName = wifeName;
    }

    public String getFamilyId() {
        return familyId;
    }

    public void setFamilyId(String familyId) {
        this.familyId = familyId;
    }

    @Override
    public String toString() {
        return "";
    }
}

Husband.java

import java.io.Serializable;

/**
 * Author: 
 * Date: 2016/11/23.
 * Time: 18:08
 */
public class Husband implements Serializable {
    private int id;
    /**丈夫名字**/
    private String husbandName;
    /**家庭ID**/
    private String familyId;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Husband(){
        
    }

    public Husband(int id, String wifeName, String familyId) {
        this.id = id;
        this.husbandName = wifeName;
        this.familyId = familyId;
    }

    public String getHusbandName() {
        return husbandName;
    }

    public void setHusbandName(String husbandName) {
        this.husbandName = husbandName;
    }

    public String getFamilyId() {
        return familyId;
    }

    public void setFamilyId(String familyId) {
        this.familyId = familyId;
    }

    @Override
    public String toString() {
        return "";
    }
}

Family.java

import java.io.Serializable;

/**
 * Author: 
 * Date: 2016/11/23.
 * Time: 18:08
 */
public class Family implements Serializable {
    /**妻子名字**/
    private String wifeName;
    /**丈夫名字**/
    private String husbandName;
    /**家庭ID**/
    private String familyId;

    public String getWifeName() {
        return wifeName;
    }

    public void setWifeName(String wifeName) {
        this.wifeName = wifeName;
    }

    public String getHusbandName() {
        return husbandName;
    }

    public void setHusbandName(String husbandName) {
        this.husbandName = husbandName;
    }

    public String getFamilyId() {
        return familyId;
    }

    public void setFamilyId(String familyId) {
        this.familyId = familyId;
    }

    @Override
    public String toString() {
        return "";
    }
}

TestFamily.java

import com.xxx.bean.Family;
import com.xxx.bean.Husband;
import com.xxx.bean.Wife;
import com.google.common.collect.Lists;
import org.junit.Test;

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

/**
 * Author: 
 * Date: 2016/11/23.
 * Time: 18:17
 */
public class TestFamily {
    @Test
    public void familyTest() {
        List<Wife> wife = Lists.newArrayList();
        wife.add(new Wife(0, "我是张三的妻子", "0001"));
        wife.add(new Wife(0, "我是李四的妻子", "0002"));
        wife.add(new Wife(0, "我是王五的妻子", "0003"));

        List<Husband> husband = Lists.newArrayList();
        husband.add(new Husband(0, "我是张三", "0001"));
        husband.add(new Husband(0, "我是李四", "0002"));
        husband.add(new Husband(0, "我是王五", "0003"));

        List<Family> families = Lists.newArrayList();
        // 将list转为Map,这里key一定要为唯一值
        Map<String, Wife> wifeMap = wife.stream().collect(
                Collectors.toMap(w -> w.getFamilyId(),
                        w -> w));
        // 匹配家庭
        families = husband.stream().map(h -> {
            return toFamily(wifeMap.get(h.getFamilyId()), h);
        }).collect(Collectors.toList());

        families.stream().forEach(family -> {
            System.out.println("家庭ID：" + family.getFamilyId() + ",丈夫：" + family.getHusbandName() + ",妻子：" + family.getWifeName());
        });
    }

    private Family toFamily(Wife wife, Husband husband) {
        Family family = new Family();
        family.setFamilyId(wife.getFamilyId());
        family.setHusbandName(husband.getHusbandName());
        family.setWifeName(wife.getWifeName());
        return family;
    }
}

最后输出结果：

家庭ID：0001,丈夫：我是张三,妻子：我是张三的妻子
家庭ID：0002,丈夫：我是李四,妻子：我是李四的妻子
家庭ID：0003,丈夫：我是王五,妻子：我是王五的妻子

这种处理办法，可以将处理此类问题的循环次数由N*N，变为2*N

如果不理解或者有更好的解决办法处理此类问题的