java 双重循环处理

List<TestOne> oneList = new ArrayList<TestOne>();

List<TestTwo> twoList = new ArrayList<TestTwo>();

oneList  赋值到 twoList .oneList属性内，根据oneList  中 id 与twoList 的 id2 判断

for (TestTwo testTwo : twoList) {

testTwo.setTestList(
oneList.stream().filter(one1 -> one1.getId() == testTwo.getId2()).collect(Collectors.toList()));

}

处理调整：

List<TestOne> oneList = new ArrayList<TestOne>();
List<TestTwo> twoList = new ArrayList<TestTwo>();

// Create a map of id2 to TestOne elements for faster lookup
Map<Integer, List<TestOne>> id2ToTestOneMap = oneList.stream()
        .collect(Collectors.groupingBy(TestOne::getId2));

// Set the testList for each element in twoList using the map
for (TestTwo testTwo : twoList) {
    int id2 = testTwo.getId2();
    testTwo.setTestList(id2ToTestOneMap.getOrDefault(id2, Collections.emptyList()));
}
 

如果更好的解决方案，请大神指点。