目录
一、主程序
二、辅助类
三、其他辅助类
四、执行结果
一、主程序
package xyz.jangle.thread.test.n6_4.collect;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.stream.Collectors;
import xyz.jangle.thread.test.n6_2.create.Person;
import xyz.jangle.thread.test.n6_2.create.PersonGenerator;
/**
* 6.4、收集流
*
* @author jangle
* @email jangle@jangle.xyz
* @time 2020年9月3日 下午9:27:11
*
*/
public class M {
public static void main(String[] args) {
// 1、收集成一个Map
List<Person> persons = PersonGenerator.generatePersonList(100);
ConcurrentMap<String, List<Person>> personByName = persons.parallelStream()
.collect(Collectors.groupingByConcurrent(Person::getFirstName));
// 遍历这个Map，并打印相关信息
personByName.keySet().forEach(key -> {
List<Person> list = personByName.get(key);
System.out.println(key + " : " + list.size());
});
// 2、串联方式收集
String resultName = persons.parallelStream().map(p -> p.toString()).collect(Collectors.joining(","));
System.out.println("串联方式收集的名称：" + resultName);
// 3、拆分为2组 薪资大于50000 和小于等于50000的
Map<Boolean, List<Person>> part = persons.parallelStream()
.collect(Collectors.partitioningBy(p -> p.getSalary() > 50000));
part.keySet().forEach(k -> {
List<Person> list = part.get(k);
System.out.println(k + ":" + list.size());
});
// 4、收集成一个Map (firstName作key， LastName做value ,当存在相同的key时，将2个value用s1+","+s2的方式拼接
Map<String, String> map = persons.parallelStream()
.collect(Collectors.toMap(p -> p.getFirstName(), p -> p.getLastName(), (s1, s2) -> s1 + "," + s2));
map.forEach((k, v) -> {
System.out.println(k + ":" + v);
});
// 5、并行处理列表，再合并列表
ArrayList<Object> highSalaryPerson = persons.parallelStream().collect(ArrayList::new, (list, p) -> {
if (p.getSalary() > 50000) {
list.add(p);
}
}, ArrayList::addAll);
System.out.println("高新人数：" + highSalaryPerson.size());
// 6、收集为ConcurrentHashMap
ConcurrentHashMap<String, Counter> peopleNames = persons.parallelStream().collect(
// 构造一个ConcurrentHashMap
ConcurrentHashMap::new,
// 向m中添加p
(m, p) -> {
// key存在时
m.computeIfPresent(p.getFirstName(), (name, counter) -> {
counter.increment();
return counter;
});
// key不存在时
m.computeIfAbsent(p.getFirstName(), name -> {
Counter counter = new Counter();
counter.setValue(name);
return counter;
});
}, (map1, map2) -> {
// 合并2个map
map2.forEach(10, (k, v) -> {
map1.merge(k, v, (v1, v2) -> {
v1.setCounter(v1.getCounter() + v2.getCounter());
return v1;
});
});
});
peopleNames.forEach((name, counter) -> {
System.out.println(name + ":" + counter.getCounter());
});
}
}
二、辅助类
package xyz.jangle.thread.test.n6_4.collect;
/**
* 辅助类
* @author jangle
* @email jangle@jangle.xyz
* @time 2020年9月3日 下午9:28:51
*
*/
public class Counter {
private String value;
private int counter;
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
public int getCounter() {
return counter;
}
public void setCounter(int counter) {
this.counter = counter;
}
public synchronized void increment() {
counter++;
}
}
三、其他辅助类
https://blog.csdn.net/Bof_jangle/article/details/108350870
四、执行结果
A : 12
B : 14
C : 12
D : 15
E : 15
F : 12
G : 20
串联方式收集的名称：D T,F Y,F X,G Y,D X,G Y,A Z,D T,G U,C Z,G Z,F V,B T,A W,E T,G Z,B U,F U,C Y,F Y,A X,G W,E W,E Y,E V,E Z,B Z,A W,C T,G X,G Y,D V,E T,C T,D T,B Y,G V,C X,E V,A U,C X,B X,E V,D U,C T,E W,E V,G Z,B V,B T,F V,E U,A Z,B T,G T,C U,B U,A V,G X,C W,G W,E W,F Z,F T,B Y,B Z,D Y,E Y,B T,E X,A T,E V,G Z,C T,D Z,D Z,A X,D Z,F Y,G X,G T,D V,D V,A V,B T,F Z,B Z,D V,A U,D T,G V,A T,G W,C U,C T,G T,F W,D T,G X,F X
false:50
true:50
A:Z,W,X,W,U,Z,V,T,X,V,U,T
B:T,U,Z,Y,X,V,T,T,U,Y,Z,T,T,Z
C:Z,Y,T,T,X,X,T,U,W,T,U,T
D:T,X,T,V,T,U,Y,Z,Z,Z,V,V,V,T,T
E:T,W,Y,V,Z,T,V,V,W,V,U,W,Y,X,V
F:Y,X,V,U,Y,V,Z,T,Y,Z,W,X
G:Y,Y,U,Z,Z,W,X,Y,V,Z,T,X,W,Z,X,T,V,W,T,X
高新人数：50
A:0
B:2
C:1
D:3
E:1
F:2
G:4
