如何为程序转换流API中的嵌套for循环

Question

List<Emp> list = Arrays.asList(
                   new Emp(123, "ABC"), new Emp(123, "BCD"), new Emp(1243, "AUBC"), 
                   new Emp(1233, "ABEC"), new Emp(1233, "ABLC")
                 );
List<Emp> listNew = new ArrayList<>();

for (int i = 0; i < list.size(); i++) {
    for (Emp emp : list) {
        if (list.get(i).getCommitId() == emp.getCommitId() && (!list.get(i).getHost().equals(emp.getHost()))) {
            Emp emp1 = new Emp();
            emp1.setCommitId(list.get(i).getCommitId());
            emp1.setHost(list.get(i).getHost());
            listNew.add(emp1);
        }
    }
}

我只需要比较两个 commitid，如果它们相同并且 host 不同，那么 return 这些数据以 emp 列表的形式出现。

Answer 1

您可以创建一个谓词来过滤具有相同提交 ID 和不同主机的 Emp，过滤流并收集到新列表

public static void main(String[] args) {
    List<Emp> list = Arrays.asList(new Emp(123, "ABC"), new Emp(123, "BCD"),
            new Emp(1243, "AUBC"), new Emp(1233, "ABEC"), new Emp(1233, "ABLC"));


    Predicate<Emp> sameCommitIdWithDifferentHost = (Emp emp) -> list.stream()
            .anyMatch(l -> l.getCommitId() == emp.getCommitId() &&
                    (!l.getHost().equals(emp.getHost())));

    List<Emp> listNew = list.stream().filter(sameCommitIdWithDifferentHost).collect(Collectors.toList());

 
}

如何为程序转换流API中的嵌套for循环

how to convert nested for loop in stream API for the program

java

collections

java-8

java-stream