I am new to JSON and I am learning using the json.simple library. I try to parse a large json file, but all i get is “OutOfMemoryError: GC overhead limit exceeded”. How can i parse large json files?
this is my code:
private static void fillPublications() throws FileNotFoundException, IOException, SQLException {
JSONParser parser = new JSONParser();
try {
String username = System.getProperty("user.name");
String filename = "Datenbank";
Object jsonData = parser.parse(new FileReader("C:\\Users\\" + username + "\\Desktop\\JSON\\" + filename + ".json"));
ArrayList<String[]> list = new ArrayList<String[]>();
JSONArray jsonArray = (JSONArray) jsonData;
Iterator iterator = jsonArray.iterator();
String name = "";
Integer count = 0;
while (iterator.hasNext()) {
String[] database = new String[11];
JSONObject obj = (JSONObject) iterator.next();
if(obj.containsKey("title")){
database[0] = (String) obj.get("title");
}
if(obj.containsKey("year")){
database[1] = obj.get("year").toString();
}
if(obj.containsKey("keywords")){
JSONArray keywords = (JSONArray) obj.get("keywords");
Iterator<String> i = keywords.iterator();
String key = "";
while (i.hasNext()) {
key = key + i.next() + "#";
}
if(key.length() > 0 && key.charAt(key.length()-1)=='#'){
key = key.substring(0, key.length()-1);
}
database[2] = key;
}
if(obj.containsKey("pages")){
database[3] = (String) obj.get("pages");
}
if(obj.containsKey("volume")){
database[4] = (String) obj.get("volume");
}
if(obj.containsKey("abstract")){
database[5] = (String) obj.get("abstract");
}
if(obj.containsKey("identifiers")){
JSONObject identifiers = (JSONObject) obj.get("identifiers");
database[6] = (String) identifiers.get("doi");
}
if(obj.containsKey("type")){
database[8] = (String) obj.get("type");
}
if(obj.containsKey("authors")){
JSONArray arr = (JSONArray) obj.get("authors");
Iterator i = arr.iterator();
while(i.hasNext()){
JSONObject authorObject = (JSONObject) i.next();
name = name + (String) authorObject.get("first_name") + " " + (String) authorObject.get("last_name") + "#";
}
if(name.length() > 0 && name.charAt(name.length()-1)=='#'){
name = name.substring(0, name.length()-1);
}
database[10] = name;
}
list.add(database);
}
System.out.println(Arrays.toString(list.get(0)));
}catch (Exception e) {
System.err.println(e);
}
}
and this is what i get:
Exception in thread "main" java.lang.OutOfMemoryError: GC overhead limit exceeded
at java.lang.StringBuffer.toString(StringBuffer.java:673)
at org.json.simple.parser.Yylex.yylex(Yylex.java:598)
at org.json.simple.parser.JSONParser.nextToken(JSONParser.java:269)
at org.json.simple.parser.JSONParser.parse(JSONParser.java:118)
at org.json.simple.parser.JSONParser.parse(JSONParser.java:92)
at JSONExtraction.fillAuthors(JSONExtraction.java:39)
at JSONExtraction.main(JSONExtraction.java:23)
C:\Users\b\AppData\Local\NetBeans\Cache\8.1\executor-snippets\run.xml:53: Java returned: 1
I built a HashMap in a class like so:
public static HashMap<String, String> makeMap(String file) {
HashMap wordMap = new HashMap<String, String>();
try {
Scanner dictionFile = new Scanner(new FileInputStream(file));
while(dictionFile.hasNextLine()) {
String[] values = new String[2];
values = dictionFile.nextLine().split(",");
wordMap.put(values[0], values[1]);
}
} catch (FileNotFoundException e) {
System.out.println("File not found!");
}
return wordMap;
}
I then call my makeMao function as follows:
HashMap dictionaryMap = Maintainance.makeMap("dictionary.txt");
String button = e.getActionCommand();
String homeUrl = "http://www.catb.org/jargon/html/";
String glossUrl = "http://www.catb.org/jargon/html/go01.html";
String searchedValue;
String completeUrl;
URL searchedUrl;
String msgPart1 = "The word you are searching for cannot be found. ";
String msgPart2 = "You are being rerouted to the glossary.";
String message = msgPart1 + msgPart2;
String title = "word Not Found";
if (button == "Search") {
String searchKey = textField.getText();
searchedValue = dictionaryMap.get(searchKey);
I cannot figure out why it is giving me the error saying:incompatible types it is pointing at my searchKey variable inside of my searchedValue statement. required is String and found is Object.
if (button == "Search")
In your above code its wrong , in Java String are compare as
if(button.equals("Search"))
Referrence
You should type-caste map
HashMap wordMap = new HashMap();
to
Map<Object,Object> wordMap =new HashMap<Object,Object>();
Now in your code
String searchKey = textField.getText();
searchedValue = dictionaryMap.get(searchKey);
I think your dicionarymap is returning an Object but you are setting it to a String.You will need to convert an Object to String first.
For example: { "primary:title":"Little Red Riding Hood"}
My Parser in Java (Android) is always getting stuck because of the colon between primary and title. I can parse anything else with ease, I just need help in this.
public class MainActivity extends Activity {
/** Called when the activity is first created. */
TextView txtViewParsedValue;
private JSONObject jsonObject;
private JSONArray jsonArray;
String [] titles, links, mediaDescriptions, mediaCredits, descriptions, dcCreators, pubDates, categories;
String [] permalinks, texts; // guid
String [] rels, hrefs;
String [] urls, media, heights, widths; // media:content
String strParsedValue = "";
private String strJSONValue;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
strJSONValue = readRawTextFile(this, R.raw.jsonextract);
txtViewParsedValue = (TextView) findViewById(R.id.text_view_1);
try {
parseJSON();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void parseJSON() throws JSONException
{
txtViewParsedValue.setText("Parse 1");
jsonObject = new JSONObject(strJSONValue);
jsonArray = jsonObject.getJSONArray("item");
titles = new String[jsonArray.length()];
links = new String[jsonArray.length()];
permalinks = new String[jsonArray.length()];
texts = new String[jsonArray.length()];
mediaDescriptions = new String[jsonArray.length()];
mediaCredits = new String[jsonArray.length()];
descriptions = new String[jsonArray.length()];
dcCreators = new String[jsonArray.length()];
pubDates = new String[jsonArray.length()];
categories = new String[jsonArray.length()];
txtViewParsedValue.setText("Parse 2");
for (int i=0; i<jsonArray.length(); i++)
{
JSONObject object = jsonArray.getJSONObject(i);
titles[i] = object.getString("title");
links[i] = object.getString("link");
JSONObject guidObj = object.getJSONObject("guid");
permalinks[i] = guidObj.getString("isPermaLink");
texts[i] = guidObj.getString("text");
//mediaDescriptions[i] = object.getString("media:description");
//mediaCredits[i] = object.getString("media:credit");
// *** THE PARSER FAILS IF THE COMMENTED LINES ARE IMPLEMENTED BECAUSE
// OF THE : IN BETWEEN THE NAMES ***
descriptions[i] = object.getString("description");
//dcCreators[i] = object.getString("dc:creator");
pubDates[i] = object.getString("pubDate");
categories[i] = object.getString("category");
}
for (int i=0; i<jsonArray.length(); i++)
{
strParsedValue += "\nTitle: " + titles[i];
strParsedValue += "\nLink: " + links[i];
strParsedValue += "\nPermalink: " + permalinks[i];
strParsedValue += "\nText: " + texts[i];
strParsedValue += "\nMedia Description: " + mediaDescriptions[i];
strParsedValue += "\nMedia Credit: " + mediaCredits[i];
strParsedValue += "\nDescription: " + descriptions[i];
strParsedValue += "\nDC Creator: " + dcCreators[i];
strParsedValue += "\nPublication Date: " + pubDates[i];
strParsedValue += "\nCategory: " + categories[i];
strParsedValue += "\n";
}
txtViewParsedValue.setText(strParsedValue);
}
public static String readRawTextFile(Context ctx, int resId)
{
InputStream inputStream = ctx.getResources().openRawResource(resId);
InputStreamReader inputreader = new InputStreamReader(inputStream);
BufferedReader buffreader = new BufferedReader(inputreader);
String line;
StringBuilder text = new StringBuilder();
try {
while (( line = buffreader.readLine()) != null) {
text.append(line);
//text.append('\n');
}
} catch (IOException e) {
return null;
}
return text.toString();
}
For one, and to answer your question, there is no issue with JSONObject and the org.json.* classes parsing keys with colons in them if they're properly formed. The following unit test passed which means it was able to parse your example scenario:
public void testParsingKeysWithColons() throws JSONException {
String raw = "{ \"primary:title\":\"Little Red Riding Hood\"}";
JSONObject obj = new JSONObject(raw);
String primaryTitle = obj.getString("primary:title");
assertEquals("Little Red Riding Hood", primaryTitle);
}
Another suggestion is that using arrays of Strings for your data is clumsy and you'd be much better organized using a data structure to represent your objects. Instead of string arrays for titles, links, descriptions; use an object that has these properties and make a list of the objects. For example:
public class MyDataStructure {
public String title;
public String primaryTitle;
public String link;
public String mediaDescription;
public static class Keys {
public static String title = "title";
public static String primaryTitle = "primary:title";
public static String link = "link";
public static String mediaDescription = "media:description";
}
}
And then you can make a "translator" class that does all the parsing for you and returns a list of your object. This is much easier to work with and keep track of. You never have to think about data misaligning or having more or less data in one of your arrays than you expected. You also have a much easier time testing where the problem is if your input data is missing anything or any of your json is malformed.
public class MyDataStructureTranslator {
public static List<MyDataStructure> parseJson(String rawJsonData) throws JSONException {
List<MyDataStructure> list = new ArrayList<MyDataStructure>();
JSONObject obj = new JSONObject(rawJsonData);
JSONArray arr = obj.getJSONArray("item");
for(int i = 0; i < arr.length(); i++) {
JSONObject current = arr.getJSONObject(i);
MyDataStructure item = new MyDataStructure();
item.title = current.getString(MyDataStructure.Keys.title);
item.primaryTitle = current.getString(MyDataStructure.Keys.primaryTitle);
item.link = current.getString(MyDataStructure.Keys.link);
item.mediaDescription = current.getString(MyDataStructure.Keys.mediaDescription);
list.add(item);
}
return list;
}
}
Since Java identifiers cannot have colons, just specify a json property name that maps to the exact json name like:
#JsonProperty("primary:title")
public String primaryTitle;
I was looking for a simple Java example using the Twitter 1.1 API and couldn't find one. Using the PHP sample posted here: Simplest PHP example for retrieving user_timeline with Twitter API version 1.1 and a few other Stackoverflow posts, I was able to come up with the following working example.
public void testUserTimelineWithAuthSample() throws Exception {
//This will read the timeline of your account.
String method = "GET";
String url = "https://api.twitter.com/1.1/statuses/user_timeline.json";
String oAuthConsumerKey = "Your value here.";
String oAuthConsumerSecret = "Your value here."; //<--- DO NOT SHARE THIS VALUE
String oAuthAccessToken = "Your value here.";
String oAuthAccessTokenSecret = "Your value here."; //<--- DO NOT SHARE THIS VALUE
String oAuthNonce = String.valueOf(System.currentTimeMillis());
String oAuthSignatureMethod = "HMAC-SHA1";
String oAuthTimestamp = time();
String oAuthVersion = "1.0";
String signatureBaseString1 = method;
String signatureBaseString2 = url;
String signatureBaseString3Templ = "oauth_consumer_key=%s&oauth_nonce=%s&oauth_signature_method=%s&oauth_timestamp=%s&oauth_token=%s&oauth_version=%s";
String signatureBaseString3 = String.format(signatureBaseString3Templ,
oAuthConsumerKey,
oAuthNonce,
oAuthSignatureMethod,
oAuthTimestamp,
oAuthAccessToken,
oAuthVersion);
String signatureBaseStringTemplate = "%s&%s&%s";
String signatureBaseString = String.format(signatureBaseStringTemplate,
URLEncoder.encode(signatureBaseString1, "UTF-8"),
URLEncoder.encode(signatureBaseString2, "UTF-8"),
URLEncoder.encode(signatureBaseString3, "UTF-8"));
System.out.println("signatureBaseString: "+signatureBaseString);
String compositeKey = URLEncoder.encode(oAuthConsumerSecret, "UTF-8") + "&" + URLEncoder.encode(oAuthAccessTokenSecret, "UTF-8");
String oAuthSignature = computeSignature(signatureBaseString, compositeKey);
System.out.println("oAuthSignature : "+oAuthSignature);
String oAuthSignatureEncoded = URLEncoder.encode(oAuthSignature, "UTF-8");
System.out.println("oAuthSignatureEncoded: "+oAuthSignatureEncoded);
String authorizationHeaderValueTempl = "OAuth oauth_consumer_key=\"%s\", oauth_nonce=\"%s\", oauth_signature=\"%s\", oauth_signature_method=\"%s\", oauth_timestamp=\"%s\", oauth_token=\"%s\", oauth_version=\"%s\"";
String authorizationHeaderValue = String.format(authorizationHeaderValueTempl,
oAuthConsumerKey,
oAuthNonce,
oAuthSignatureEncoded,
oAuthSignatureMethod,
oAuthTimestamp,
oAuthAccessToken,
oAuthVersion);
System.out.println("authorizationHeaderValue: "+authorizationHeaderValue);
System.out.println("url: "+url);
System.out.println("authorizationHeaderValue:"+authorizationHeaderValue);
GetMethod getMethod = new GetMethod(url);
getMethod.addRequestHeader("Authorization", authorizationHeaderValue);
HttpClient cli = new HttpClient();
int status = cli.executeMethod(getMethod);
System.out.println("Status:"+status);
long responseContentLength = getMethod.getResponseContentLength();
System.out.println("responseContentLength:"+responseContentLength);
String response = getMethod.getResponseBodyAsString();
System.out.println("response: "+response);
}
private static String computeSignature(String baseString, String keyString) throws GeneralSecurityException, UnsupportedEncodingException, Exception
{
SecretKey secretKey = null;
byte[] keyBytes = keyString.getBytes();
secretKey = new SecretKeySpec(keyBytes, "HmacSHA1");
Mac mac = Mac.getInstance("HmacSHA1");
mac.init(secretKey);
byte[] text = baseString.getBytes();
return new String(Base64.encodeBase64(mac.doFinal(text))).trim();
}
private String time() {
long millis = System.currentTimeMillis();
long secs = millis / 1000;
return String.valueOf( secs );
}
However, if I add parameters to the url like:
String url = "https://api.twitter.com/1.1/statuses/user_timeline.json?screen_name=twitterapi&count=2";
I get:
response: {"errors":[{"message":"Could not authenticate you","code":32}]}
Any idea where this is going wrong?
This works excellent for Timeline with the new Twitter API 1.1
1) Download twitter4j-core-3.0.3.jar in http://twitter4j.org/en/
2) Try use this code:
private static final String TWITTER_CONSUMER_KEY = "xxxxxxxxxxxxxxxxxx";
private static final String TWITTER_SECRET_KEY = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
private static final String TWITTER_ACCESS_TOKEN = "xxxxxxxxxxxxxxxxxxxxxxx";
private static final String TWITTER_ACCESS_TOKEN_SECRET = "xxxxxxxxxxxxxxxxxxxxxxxxx";
ConfigurationBuilder cb = new ConfigurationBuilder();
cb.setDebugEnabled(true)
.setOAuthConsumerKey(TWITTER_CONSUMER_KEY)
.setOAuthConsumerSecret(TWITTER_SECRET_KEY)
.setOAuthAccessToken(TWITTER_ACCESS_TOKEN)
.setOAuthAccessTokenSecret(TWITTER_ACCESS_TOKEN_SECRET);
TwitterFactory tf = new TwitterFactory(cb.build());
Twitter twitter = tf.getInstance();
try {
Query query = new Query("MrEdPanama");
QueryResult result;
do {
result = twitter.search(query);
List<Status> tweets = result.getTweets();
for (Status tweet : tweets) {
System.out.println("#" + tweet.getUser().getScreenName() + " - " + tweet.getText());
}
} while ((query = result.nextQuery()) != null);
System.exit(0);
} catch (TwitterException te) {
te.printStackTrace();
System.out.println("Failed to search tweets: " + te.getMessage());
System.exit(-1);
}
You are wrong with the oauth_nonce. It is a random 32 bytes string encoded in base 64.
You can build them like this :
public String generateNonce() {
Random gen = new Random(System.currentTimeMillis());
StringBuilder nonceBuilder = new StringBuilder("");
String base = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
int baseLength = base.length();
// Taking random word characters
for (int i = 0; i < 32; ++i) {
int position = gen.nextInt(baseLength);
nonceBuilder.append(base.charAt(position));
}
String nonce = toBase64(nonceBuilder.toString());
return nonce;
}
// In your code :
String oAuthNonce = generateNonce();
With String toBase64(String); which is a method to encode a String with Base 64.
Here's a Twitter 1.1 API example that works with parameters. The issue was not related to the nonce. It was the signatureBaseString. Think of the signatureBaseString as a 3 part string delimited by the ampersand (METHOD&URL&PARAMS). The api parameters are NOT to be included in the 2nd part of the signatureBaseString, they are to be included (with the other 6 security parameters) in the last part of signatureBaseString (Also, those params must be in alphabetic order).
public void testUserTimelineWithParams() throws Exception {
//This will read the timeline of the 'twitterapi' account.
String method = "GET";
String url = "https://api.twitter.com/1.1/statuses/user_timeline.json";
List<NameValuePair> urlParams = new ArrayList<NameValuePair>();
urlParams.add( new NameValuePair("screen_name","twitterapi") );
urlParams.add( new NameValuePair("count", "10") );
String oAuthConsumerKey = "Your value";
String oAuthConsumerSecret = "Your value"; //<--- DO NOT SHARE THIS VALUE
String oAuthAccessToken = "Your value";
String oAuthAccessTokenSecret = "Your value"; //<--DO NOT SHARE THIS VALUE
String oAuthNonce = String.valueOf(System.currentTimeMillis());
String oAuthSignatureMethod = "HMAC-SHA1";
String oAuthTimestamp = time();
String oAuthVersion = "1.0";
String signatureBaseString1 = method;
String signatureBaseString2 = url;
List<NameValuePair> allParams = new ArrayList<NameValuePair>();
allParams.add(new NameValuePair("oauth_consumer_key", oAuthConsumerKey));
allParams.add(new NameValuePair("oauth_nonce", oAuthNonce));
allParams.add(new NameValuePair("oauth_signature_method", oAuthSignatureMethod));
allParams.add(new NameValuePair("oauth_timestamp", oAuthTimestamp));
allParams.add(new NameValuePair("oauth_token", oAuthAccessToken));
allParams.add(new NameValuePair("oauth_version", oAuthVersion));
allParams.addAll(urlParams);
Collections.sort(allParams, new NvpComparator());
StringBuffer signatureBaseString3 = new StringBuffer();
for(int i=0;i<allParams.size();i++)
{
NameValuePair nvp = allParams.get(i);
if (i>0) {
signatureBaseString3.append("&");
}
signatureBaseString3.append(nvp.getName() + "=" + nvp.getValue());
}
String signatureBaseStringTemplate = "%s&%s&%s";
String signatureBaseString = String.format(signatureBaseStringTemplate,
URLEncoder.encode(signatureBaseString1, "UTF-8"),
URLEncoder.encode(signatureBaseString2, "UTF-8"),
URLEncoder.encode(signatureBaseString3.toString(), "UTF-8"));
System.out.println("signatureBaseString: "+signatureBaseString);
String compositeKey = URLEncoder.encode(oAuthConsumerSecret, "UTF-8") + "&" + URLEncoder.encode(oAuthAccessTokenSecret, "UTF-8");
String oAuthSignature = computeSignature(signatureBaseString, compositeKey);
System.out.println("oAuthSignature : "+oAuthSignature);
String oAuthSignatureEncoded = URLEncoder.encode(oAuthSignature, "UTF-8");
System.out.println("oAuthSignatureEncoded: "+oAuthSignatureEncoded);
String authorizationHeaderValueTempl = "OAuth oauth_consumer_key=\"%s\", oauth_nonce=\"%s\", oauth_signature=\"%s\", oauth_signature_method=\"%s\", oauth_timestamp=\"%s\", oauth_token=\"%s\", oauth_version=\"%s\"";
String authorizationHeaderValue = String.format(authorizationHeaderValueTempl,
oAuthConsumerKey,
oAuthNonce,
oAuthSignatureEncoded,
oAuthSignatureMethod,
oAuthTimestamp,
oAuthAccessToken,
oAuthVersion);
System.out.println("authorizationHeaderValue: "+authorizationHeaderValue);
StringBuffer urlWithParams = new StringBuffer(url);
for(int i=0;i<urlParams.size();i++) {
if(i==0)
{
urlWithParams.append("?");
}
else
{
urlWithParams.append("&");
}
NameValuePair urlParam = urlParams.get(i);
urlWithParams.append(urlParam.getName() + "=" + urlParam.getValue());
}
System.out.println("urlWithParams: "+urlWithParams.toString());
System.out.println("authorizationHeaderValue:"+authorizationHeaderValue);
GetMethod getMethod = new GetMethod(urlWithParams.toString());
getMethod.addRequestHeader("Authorization", authorizationHeaderValue);
HttpClient cli = new HttpClient();
int status = cli.executeMethod(getMethod);
System.out.println("Status:"+status);
long responseContentLength = getMethod.getResponseContentLength();
System.out.println("responseContentLength:"+responseContentLength);
String response = getMethod.getResponseBodyAsString();
System.out.println("response: "+response);
}
private static String computeSignature(String baseString, String keyString) throws GeneralSecurityException, UnsupportedEncodingException, Exception
{
SecretKey secretKey = null;
byte[] keyBytes = keyString.getBytes();
secretKey = new SecretKeySpec(keyBytes, "HmacSHA1");
Mac mac = Mac.getInstance("HmacSHA1");
mac.init(secretKey);
byte[] text = baseString.getBytes();
return new String(Base64.encodeBase64(mac.doFinal(text))).trim();
}
private String time() {
long millis = System.currentTimeMillis();
long secs = millis / 1000;
return String.valueOf( secs );
}
Where the NvpComparator is:
public class NvpComparator implements Comparator<NameValuePair> {
public int compare(NameValuePair arg0, NameValuePair arg1) {
String name0 = arg0.getName();
String name1 = arg1.getName();
return name0.compareTo(name1);
}
}
Here is my solution using twitter4j lib
Twitter twitter = new TwitterFactory().getInstance();
AccessToken accessToken = new AccessToken(accessTokenStr, accessTokenSecretStr);
twitter.setOAuthConsumer(consumerKeyStr, consumerSecretStr);
twitter.setOAuthAccessToken(accessToken);
try {
Query query = new Query("#<HASHTAG TO SEARCH>");
QueryResult result;
result = twitter.search(query);
List<Status> tweets = result.getTweets();
for (Status tweet : tweets) {
System.out.println("#" + tweet.getUser().getScreenName() + " - " + tweet.getText());
}
}
catch (TwitterException te) {
te.printStackTrace();
System.out.println("Failed to search tweets: " + te.getMessage());
System.exit(-1);
}
public class Readparam
{
private static String method_name;
public static HashMap<String, Vector<String>> getParameters(String file_name)
{
HashMap temp_map = new HashMap();
String current_dir = System.getProperty("user.dir");
File new_file = new File(current_dir + "\\parameters\\" + file_name);
StringTokenizer stringtok = null;
StringBuffer temp_contents = new StringBuffer();
BufferedReader input = null;
try
{
input = new BufferedReader(new FileReader(new_file));
String current_line = null;
while (((current_line = input.readLine()) != null) && (current_line.length() > 0))
{
stringtok = new StringTokenizer(current_line, "(");
method_name = stringtok.nextToken();
String parsed_parameters = current_line.subSequence(current_line.indexOf("(") + 1, current_line.indexOf(")")).toString();
StringTokenizer paramtok = new StringTokenizer(parsed_parameters, ",");
String[] parsed_string = parsed_parameters.split(", ");
String parsing = method_name + "(";
for (int i = 0; i < parsed_string.length; i++)
{
String[] temp_parse = parsed_string[i].split(" ");
if (i < parsed_string.length - 1)
parsing = parsing + temp_parse[0] + ", ";
else {
parsing = parsing + temp_parse[0];
}
}
parsing = parsing + ")";
Vector temp_vector = new Vector();
for (String s : parsed_string) {
temp_vector.add(s);
}
temp_map.put(parsing, temp_vector);
}
}
catch (FileNotFoundException ex)
{
System.out.println("File not found: " + file_name);
String method_name = null;
return method_name;
}
any help on this is aprreciated
I have the last line "return method_name that does not compile
i recieve an error incompatible types, expected java.util.hashmap found java.lang.String
the last line return method_name does not compile
System.out.println("File not found: " + file_name);
HashMap<String, Vector<String>> method_name = null;
return method_name;
Since your method is of a certain type, you need to 'cast' the value that's being returned to that type.
If you are coding using Eclipse, you can just click on the little error icon, and it will offer to fix the error for you, and it will cast it for you. If you are not using Eclipse, you might consider it in the future. (NetBeans works in a similar manner)
Your method is declared to return HashMap<String, Vector<String>> (which is odd to start with - usually you'd use List rather than Vector if you're using the Java 2 collections). But then your only return statement is here:
String method_name = null;
return method_name;
That's clearly not returning a HashMap<String, Vector<String>>, is it? What do you expect that to do? You could just write
return null;
which would return a null reference as a HashMap<String, Vector<String>>. (Personally I'd just let the exception bubble up, but that's a different matter.)
(It also doesn't help that you haven't shown the end of your method, and that some of the indentation is decidedly odd.)