Develop Reference

How to load saved item from JSON file in java

I am making an app where user can change theme (dark and light mood) as per his convenience. And the theme that the user chooses will be saved and the saved theme will be there when the app is opened again later.
I have saved the data to file using JSON.
And when the user clicks on the theme change button, the data will be written to the file.
The code of the theme:
private void darkTheme() {
FlatDarkLaf.setup();
UIManager.put("TextField.foreground", new ColorUIResource(Color.WHITE));
UIManager.put("Label.foreground", new ColorUIResource(Color.WHITE));
UIManager.put("Button.foreground", new ColorUIResource(Color.WHITE));
SwingUtilities.updateComponentTreeUI(contentPane);
for(int i=0; i<arList.size(); i++) {
((JLabel)arList.get(i).getRenderer()).setHorizontalAlignment(SwingConstants.CENTER);
}
}
And the Code for the theme change and write to the file button:
btnDark.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String path = "resources/config.cfg";
JSONObject json = new JSONObject();
try {
json.put("Theme", "darkTheme();");
} catch (JSONException ex) {
ex.printStackTrace();
}
try (PrintWriter out = new PrintWriter(new FileWriter(path))) {
out.write(json.toString());
} catch (Exception ex) {
ex.printStackTrace();
}
darkTheme();
}
});
I can read the file but can't Load the save data.
Here the code for read the file:
private void readData() {
try {
String path = "resources/config.cfg";
InputStream is = Button.class.getResourceAsStream(path);
if (is == null) {
throw new NullPointerException("Cannot find resource file " + path);
}
JSONTokener tokener = new JSONTokener(is);
JSONObject object = new JSONObject(tokener);
// object.getString("darkTheme();");
object.getJSONObject("Theme");
}
catch (Exception e) {
}
}
Can anyone please help me how to do this correctly.

Ok Finally I've got a solution by my own and someone's idea.
I have changed the line in btnDark
json.put("Theme", "darkTheme();");
to
json.put("Theme", "Dark");
and in the readData() method I write like this
private void readData() {
String jsonText;
try {
String path = "resources/config.cfg";
jsonText = IOUtils.toString(new FileInputStream(new File(path)));
int i = jsonText.indexOf("{");
jsonText = jsonText.substring(i);
JSONObject ob = new JSONObject(jsonText);
String Theme = ob.getString("Theme");
if(Theme.equals("Dark")) {
darkTheme();
}
else if(Theme.equals("Light")) {
lightTheme();
}
}catch(Exception ex) {
ex.printStackTrace();
}
}
And now it's work perfectly

Error writing a file in Android 11 passing a variable as file name

I am trying to save files created in a specific directory I choose. I have many reason why I am doing this not locally.
My app had as target up to Android 10, but now I am trying to target Android 11 as well and so far everything works, except for one thing, the files are not saved if I pass a string variable as file name instead of a written name in the StringBuilder.
Let me explain you showing the working code and the not working code:
////WORKING
public class MyLoggerUtility {
private static String filename = "MyMonitoring_Log";
static boolean isExternalStorageAvailable = false;
static boolean isExternalStorageWriteable = false;
static String state = Environment.getExternalStorageState();
public static void addRecordToLog(String var0) {
if ("mounted".equals(state)) {
isExternalStorageWriteable = true;
isExternalStorageAvailable = true;
} else if ("mounted_ro".equals(state)) {
isExternalStorageAvailable = true;
isExternalStorageWriteable = false;
} else {
isExternalStorageWriteable = false;
isExternalStorageAvailable = false;
}
File var1 = new File("/sdcard/MYPATH/LOG");
if ("mounted".equals(state)) {
if (!var1.exists()) {
Log.d("Dir created ", "Dir created ");
var1.mkdirs();
}
StringBuilder var6 = new StringBuilder();
var6.append("/sdcard/MYPATH/LOG/");
var6.append(filename);
var6.append(".txt");
File var2 = new File(var6.toString());
if (!var2.exists()) {
try {
Log.d("File created ", "File created ");
var2.createNewFile();
} catch (IOException var5) {
var5.printStackTrace();
}
}
try {
FileWriter var3 = new FileWriter(var2, true);
BufferedWriter var7 = new BufferedWriter(var3);
StringBuilder var8 = new StringBuilder();
var8.append(var0);
var8.append("\r\n");
var7.write(var8.toString());
var7.flush();
var7.close();
} catch (IOException var4) {
var4.printStackTrace();
}
}
}
}
And the not working one:
////NOT WORKING
public class MyLoggerUtility {
static boolean isExternalStorageAvailable = false;
static boolean isExternalStorageWriteable = false;
static String state = Environment.getExternalStorageState();
public static void addRecordToLog(String var0, String fileName) {
if ("mounted".equals(state)) {
isExternalStorageWriteable = true;
isExternalStorageAvailable = true;
} else if ("mounted_ro".equals(state)) {
isExternalStorageAvailable = true;
isExternalStorageWriteable = false;
} else {
isExternalStorageWriteable = false;
isExternalStorageAvailable = false;
}
File var1 = new File("/sdcard/MYPATH/LOG");
if ("mounted".equals(state)) {
if (!var1.exists()) {
Log.d("Dir created ", "Dir created ");
var1.mkdirs();
}
StringBuilder var6 = new StringBuilder();
var6.append("/sdcard/MYPATH/LOG/");
var6.append(fileName); ================> USING THIS IT DOES NOT WRITE THE FILE
var6.append(".txt");
File var2 = new File(var6.toString());
if (!var2.exists()) {
try {
Log.d("File created ", "File created ");
var2.createNewFile();
} catch (IOException var5) {
var5.printStackTrace();
}
}
try {
FileWriter var3 = new FileWriter(var2, true);
BufferedWriter var7 = new BufferedWriter(var3);
StringBuilder var8 = new StringBuilder();
var8.append(var0);
var8.append("\r\n");
var7.write(var8.toString());
var7.flush();
var7.close();
} catch (IOException var4) {
var4.printStackTrace();
}
}
}
}
I have no idea why this does not works only in Android 11. I have all the permits, as I said it does work with the first example, the problem happens only when using the second one.
If i run the log to watch errors i get the Exception: Operation not permitted.
But it does not make any sense to me because if i use "123" instead of my variable it does create it.
Thank you in advance for everyone who will have a look.
UPDATE: Solved thanks to the user #blackapps, answer in the comments.
I was using ":" character in the file name, it was working up to Android 10 but in Android 11 it caused the file not being created.

Print To File in Java

i have a problem in my java exercise.
i need to print a multiply contact information to a file, but when i print more then 1 contact, only 1 contact is displayed in the file..
i tried to debug that but i cant find any mistake
i will put the code of my classes here:
This is Demo Class which i run the code from
public class Demo {
public static void main(String[] args) {
System.out.println("Insert number of Contacts:");
Scanner scanner = new Scanner(System.in);
int val = scanner.nextInt();
Contact[] contacts = new Contact[val];
for(int i = 0 ; i < val; i++) {
System.out.println("Contact #"+(i+1));
System.out.print("Owner: \n");
String owner = scanner.next();
System.out.print("Phone number: \n");
String phoneNum = scanner.next();
System.out.print("Please Select Group:\n"
+ "1 For FRIENDS,\n" +
"2 For FAMILY,\n" +
"3 For WORK,\n" +
"4 For OTHERS");
int enumNum = scanner.nextInt();
Group group;
switch(enumNum) {
case 1:
group=Group.FRIENDS;
break;
case 2:
group=Group.FAMILY;
break;
case 3:
group=Group.WORK;
break;
default:
group=Group.OTHERS;
}//switch end
contacts[i] = new Contact(owner,phoneNum,group);
}//loop end
System.out.println("Insert File name");
String fileName = scanner.next();
File f=null;
for(int i = 0 ; i < val; i++) {
if(i==0) {
f = new File(fileName);
contacts[0].Save(fileName);
}
else {
contacts[i].Save(f);
}
}
}
}
This is Contact Class:
enum Group {
FRIENDS,
FAMILY,
WORK,
OTHERS
};
public class Contact {
private String phoneNumber,owner;
private Group group;
PrintWriter pw = null;
public Contact(String owner ,String phoneNumber,Group group) {
setPhoneNumber(phoneNumber);
setOwner(owner);
setGroup(group);
}
public Contact(String fileName) {
File file = new File(fileName+".txt");
try {
Scanner scanner = new Scanner(file);
phoneNumber=scanner.nextLine();
owner=scanner.nextLine();
String str=scanner.nextLine();
group = Group.valueOf(str);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
catch(Exception e) {
e.printStackTrace();
}
}
public Contact(File file) {
try {
Scanner scanner = new Scanner(file);
phoneNumber=scanner.nextLine();
owner=scanner.nextLine();
String str=scanner.nextLine();
group = Group.valueOf(str);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
catch(Exception e) {
e.printStackTrace();
}
}
public String getPhoneNumber() {
return phoneNumber;
}
public void setPhoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
}
public String getOwner() {
return owner;
}
public void setOwner(String owner) {
this.owner = owner;
}
public Group getGroup() {
return group;
}
public void setGroup(Group group) {
this.group = group;
}
public void Save(String fileName) {
File f = new File(fileName+".txt");
try {
if(f.createNewFile()) {
System.out.println("File created");
pw = new PrintWriter(f); //יצירת מדפסת לקובץ
pw.println(phoneNumber+"\n"+owner+"\n"+group+"\n\n\n");
}
} catch (IOException e) {
e.printStackTrace();
}
pw.close();
}
public void Save(File f) {
PrintWriter pw=null;
try {
pw = new PrintWriter(f);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
pw.println(phoneNumber+"\n"+owner+"\n"+group);
pw.close();
}
public String toString() {
return phoneNumber+"\n"+owner+"\n"+group;
}
}

Every time you create PrintWriter the file is being overwritten. Since you create a new PrintWriter for each contact, the file contains only the last contact information. What you should do is to create PrintWriter only once and use it for all contacts.
Firstly, let's create a new save method with such signature:
public void save(PrintWriter writer)
I have also used the lowercase name of the method due to Java naming convention.
Now the implementation of save method will look like this:
writer.println(phoneNumber);
writer.println(owner);
writer.println(group + "\n\n\n");
Then we should replace the usage of Save method with the new one. Here is your code:
String fileName = scanner.next();
File f = null;
for (int i = 0; i < val; i++) {
if(i == 0) {
f = new File(fileName);
contacts[0].Save(fileName);
} else {
contacts[i].Save(f);
}
}
In order to fix the issue we can change it like this:
String fileName = scanner.next();
File file = new File(fileName);
try (PrintWriter writer = new PrintWriter(file)) {
for (int i = 0; i < val; i++) {
contacts[i].save(writer);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
I have also used try-with-resources which closes the PrintWriter automatically.

From the Javadoc of the constructor of PrintWriter:
public PrintWriter​(File file)
Parameters: file - The file to use as the destination of this writer. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
In the Save function you create a PrintWriter everytime. So everytime the file is truncated, and then you lose the contact you saved before.

Since File I/O classes in java use Decorator Design pattern, you can use a FileWriter to take advantage of appending to a file. So you can use this code for Save() method :
public void Save(String fileName) {
File f = new File(fileName+".txt");
try {
//System.out.println("File created"); You don't need to create new file.
FileWriter fw=new FileWriter(f,true):// second argument enables append mode
pw = new PrintWriter(fw); //יצירת מדפסת לקובץ
pw.println(phoneNumber+"\n"+owner+"\n"+group+"\n\n\n");
} catch (IOException e) {
e.printStackTrace();
}
pw.close();
}

how to remove 503 exceptions in java

I have a list of names in the form of a CSV and I am up for google searching those names using java. But the problem that i am facing is that when i initially run the code i am able to search the query but in the middle of the code the code starts to throw 503 exceptions and when i again run the code it starts throwing 503 exceptions from the very beginning.Here is the code that i am using.
public class ExtractInformation
{
static String firstname,middlename,lastname;
public static final int PAGE_NUMBERS = 10;
public static void readCSV()
{
boolean first = true;
try
{
String splitBy = ",";
BufferedReader br = new BufferedReader(new FileReader("E:\\KOLDump\\names.csv"));
String line = null;
String site = null;
while((line=br.readLine())!=null)
{
if(first)
{
first = false;
continue;
}
String[] b = line.split(splitBy);
firstname = b[0];
middlename = b[1];
lastname = b[2];
String name = null;
if(middlename == null || middlename.length() == 0)
{
name = firstname+" "+lastname+" OR "+lastname+" "+firstname.charAt(0);
}
else
{
name = firstname+" "+lastname+" OR "+lastname+" "+firstname.charAt(0)+" OR "+firstname+" "+middlename.charAt(0)+". "+lastname;
}
BufferedReader brs = new BufferedReader(new FileReader("E:\\KOLDump\\site.csv"));
while((site = brs.readLine()) != null)
{
if(first)
{
first = false;
continue;
}
String [] s = site.split(splitBy);
String siteName = s[0];
siteName = (siteName.replace("www.", ""));
siteName = (siteName.replace("http://", ""));
getDataFromGoogle(name.trim(), siteName.trim());
}
brs.close();
}
//br.close();
}
catch(Exception e)
{
System.out.println("unable to read file...some problem in the csv");
}
}
public static void main(String[] args)
{
readCSV();
}
private static void getDataFromGoogle(String query,String siteName)
{
Set<String> result = new HashSet<String>();
String request = "http://www.google.co.in/search?q="+query+" "+siteName;
try
{
Document doc = Jsoup.connect(request).userAgent("Chrome").timeout(10000).get();
Element query_results = doc.getElementById("ires");
Elements gees = query_results.getElementsByClass("g");
for(Element gee : gees)
{
Element h3 = gee.getElementsByTag("h3").get(0);
String annotation = h3.getElementsByTag("a").get(0).attr("href");
if(annotation.split("q=",2)[1].contains(siteName))
{
System.out.println(annotation.split("q=",2)[1]);
}
}
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
any suggestions on how to remove this exceptions from the code would really be helpful.

If you wait a little do the 503's go away? If so, then you're probably being rate-limited by Google. https://support.google.com/gsa/answer/2686272?hl=en
You may need to put some kind of delay between requests.

Do Not Crawl certain page in a particular link(exclude certain url from crawling)

This is the below code in my MyCrawler.java and it is crawling all those links that I have provided in href.startsWith but suppose If I do not want to crawl this particular page http://inv.somehost.com/people/index.html then how can I do this in my code..
public MyCrawler() {
}
public boolean shouldVisit(WebURL url) {
String href = url.getURL().toLowerCase();
if (href.startsWith("http://www.somehost.com/") || href.startsWith("http://inv.somehost.com/") || href.startsWith("http://jo.somehost.com/")) {
//And If I do not want to crawl this page http://inv.somehost.com/data/index.html then how it can be done..
return true;
}
return false;
}
public void visit(Page page) {
int docid = page.getWebURL().getDocid();
String url = page.getWebURL().getURL();
String text = page.getText();
List<WebURL> links = page.getURLs();
int parentDocid = page.getWebURL().getParentDocid();
try {
URL url1 = new URL(url);
System.out.println("URL:- " +url1);
URLConnection connection = url1.openConnection();
Map responseMap = connection.getHeaderFields();
Iterator iterator = responseMap.entrySet().iterator();
while (iterator.hasNext())
{
String key = iterator.next().toString();
if (key.contains("text/html") || key.contains("text/xhtml"))
{
System.out.println(key);
// Content-Type=[text/html; charset=ISO-8859-1]
if (filters.matcher(key) != null){
System.out.println(url1);
try {
final File parentDir = new File("crawl_html");
parentDir.mkdir();
final String hash = MD5Util.md5Hex(url1.toString());
final String fileName = hash + ".txt";
final File file = new File(parentDir, fileName);
boolean success =file.createNewFile(); // Creates file crawl_html/abc.txt
System.out.println("hash:-" + hash);
System.out.println(file);
// Create file if it does not exist
// File did not exist and was created
FileOutputStream fos = new FileOutputStream(file, true);
PrintWriter out = new PrintWriter(fos);
// Also could be written as follows on one line
// Printwriter out = new PrintWriter(new FileWriter(args[0]));
// Write text to file
Tika t = new Tika();
String content= t.parseToString(new URL(url1.toString()));
out.println("===============================================================");
out.println(url1);
out.println(key);
//out.println(success);
out.println(content);
out.println("===============================================================");
out.close();
fos.flush();
fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TikaException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// http://google.com
}
}
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
System.out.println("=============");
}
And this is my Controller.java code from where MyCrawler is getting called..
public class Controller {
public static void main(String[] args) throws Exception {
CrawlController controller = new CrawlController("/data/crawl/root");
controller.addSeed("http://www.somehost.com/");
controller.addSeed("http://inv.somehost.com/");
controller.addSeed("http://jo.somehost.com/");
controller.start(MyCrawler.class, 20);
controller.setPolitenessDelay(200);
controller.setMaximumCrawlDepth(2);
}
}
Any suggestions will be appreciated..

How about adding a property to tell which urls you want to exclude.
Add to your exclusions list all the pages that you don't want them to get crawled.
Here is an example:
public class MyCrawler extends WebCrawler {
List<Pattern> exclusionsPatterns;
public MyCrawler() {
exclusionsPatterns = new ArrayList<Pattern>();
//Add here all your exclusions using Regular Expresssions
exclusionsPatterns.add(Pattern.compile("http://investor\\.somehost\\.com.*"));
}
/*
* You should implement this function to specify
* whether the given URL should be visited or not.
*/
public boolean shouldVisit(WebURL url) {
String href = url.getURL().toLowerCase();
//Iterate the patterns to find if the url is excluded.
for (Pattern exclusionPattern : exclusionsPatterns) {
Matcher matcher = exclusionPattern.matcher(href);
if (matcher.matches()) {
return false;
}
}
if (href.startsWith("http://www.ics.uci.edu/")) {
return true;
}
return false;
}
}
In this example we are telling that all urls that start with http://investor.somehost.com should not be crawled.
So these wont be crawled:
http://investor.somehost.com/index.html
http://investor.somehost.com/something/else
I recommend you reading about regular expresions.