如何在Java 8中遍历JSONArray

Question

我有以下代码，它使用for loop来遍历中的元素JSONArray。

import org.apache.log4j.Logger;
import org.json.JSONArray;
import org.json.JSONObject;

import java.util.stream.IntStream;
    public class Pmt {
    private String[] patchInformation_svnRevisionpublic;
    private final Logger logger = Logger.getLogger(Pmt.class.getName());

        private static final String COMMITS_IN_PATCH_IDENTIFIER = "patchInformation_svnRevisionpublic";  //key used to identify the commits in a patch from JSON response received from PMT
        private static final String KEY_STRING = "name";
        private static final String VALUE_STRING = "value";

         public String[] getPublicGitCommitHashes(JSONArray jsonArray) {

            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject jsonObject = (JSONObject) jsonArray.get(i);
                String tempName = (String) jsonObject.get(KEY_STRING);
                if (tempName.equals(COMMITS_IN_PATCH_IDENTIFIER)) {
                    JSONArray tempCommitsJSONArray = (JSONArray) jsonObject.get(VALUE_STRING);
                    //initializing the patchInformation_svnRevisionpublic array
                    patchInformation_svnRevisionpublic = new String[tempCommitsJSONArray.length()];
                    // for ommiting the white spaces at the begingin and end of the commits
                    IntStream.range(0, tempCommitsJSONArray.length()).forEach(j -> patchInformation_svnRevisionpublic[j] = ((String) tempCommitsJSONArray.get(j)).trim());

                    logger.info(" The commits hashes obtained from WSO2 PMT are successfully saved to an array");

                    System.out.println("The commit Ids are");
                    //            for printing all the commits ID associated with a patch
                    IntStream.range(0, patchInformation_svnRevisionpublic.length).mapToObj(i1 -> patchInformation_svnRevisionpublic[i1]).forEach(System.out::println);
                    System.out.println();
                    break;
                }
            }
            //to prevent from internaal representation by returning referecnce to mutable object
            String clonedPatchInformation_svnRevisionpublic[] = patchInformation_svnRevisionpublic.clone();
            return clonedPatchInformation_svnRevisionpublic;
        }
    }

我如何使用Java 8like中的新功能streams API或forEach执行相同任务。提前致谢

Answer 1

这等效于Java 8流API中的代码。不是100％等效，但是您可以了解主要思想。

private static final String COMMITS_IN_PATCH_IDENTIFIER = "patchInformation_svnRevisionpublic";  //key used to identify the commits in a patch from JSON response received from PMT
private static final String KEY_STRING = "name";
private static final String VALUE_STRING = "value";

public List<String> getCommitIds (JSONArray array) {
     return arrayToStream(array)
            .map(JSONObject.class::cast)
            .filter(o -> o.get(KEY_STRING).equals(COMMITS_IN_PATCH_IDENTIFIER))
            .findFirst()
            .map(o -> (JSONArray) o.get(VALUE_STRING))
            .map(Main::arrayToStream)
            .map(commits ->
                    commits.map(Object::toString)
                            .map(String::trim)
                            .collect(Collectors.toList())
            )
            .orElseGet(Collections::emptyList);
}

@Nonnull
private static Stream<Object> arrayToStream(JSONArray array) {
    return StreamSupport.stream(array.spliterator(), false);
}