I am connecting to an Oracle database and querying multiple tables. My current code creates the connection and calls a PL/SQL function which contains the query. Once I have the result set, I add it to a Vector (as I am unsure the number of records each query will result in).
My problem is that I am unsure how to write a delimited file from the Vector. I imagine once I have added my result set to it, it is simply one gigantic string. I need to be able to receive each field from the query and delimit between them, as well as keep rows separate.
Here is my code:
public static void main(String[] args) throws SQLException {
// instantiate db connection
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
}catch (Exception e) {
throw new SQLException("Oracle JDBC is not available", e);
}
// define connection string and parameters
String url = "jdbc:oracle:thin:#//host:port/sid";
Connection conn = DriverManager.getConnection(url, "USERNAME","PASSWORD");
CallableStatement stmt = conn.prepareCall("{? = CALL <functionname>(?)}");
// get result set and add to a Vector
ResultSet rs = stmt.executeQuery();
Vector<String> results = new Vector();
while ( rs.next() ){
results.add(rs.getString(1));
}
// close result set, sql statement, and connection
rs.close();
stmt.close();
conn.close();
// write Vector to output file,
// where the file name format is MMddyyyy.txt
try {
Calendar cal = Calendar.getInstance();
SimpleDateFormat sdf = new SimpleDateFormat("MMddyyyy");
String dateStr = sdf.format(cal.getTime());
FileWriter fwrite = new FileWriter(dateStr + ".txt");
BufferedWriter out = new BufferedWriter(fwrite);
for(int i = 0; i < results.size(); i++)
{
String temp = results.elementAt(i);
out.write(temp);
}
out.close();
}catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
}
I am just unsure how to go about getting the information from the db and writing it to a delimited file. Thanks in advance!
If you are unsure about the number of fields in each of your rows, then probably, it won't be possible. Because to fetch all the field values from database, you need to know what is the type of each fields, and the number of fields.
But, I'll post an example for when you have fixed number of fields, that you know.
Suppose you have 4 columns per row. Now to display it in tabular form, you would have to use List of List.
If you are using Vector, use Vector of List.
Here's an example for List of List: -
List<List<String>> results = new ArrayList<List<String>>();
while ( rs.next() ) {
List<String> tempList = new ArrayList<String>();
tempList.add(rs.getString(1));
tempList.add(rs.getString(2));
tempList.add(rs.getString(3));
tempList.add(rs.getString(4));
results.add(tempList);
}
Then to print it, use this loop: -
for (List<String> innerList: results) {
for (String fields: innerList) {
System.out.print(fields + "\t");
}
System.out.println();
}
You can write it in the same form to your BufferedWriter.
Use results.toString() and truncate the braces([]) from resulting string to write all values as comma separated at once in the file.
//toString() returns comma separated string values enclosed in []
String resultString = results.toString();
//truncate leading '[' and termincating ']'
resultString = resultString.substring(1, resultString.length()-1);
//if comma is not your delimiter then use String.replaceAll()
//to replace `,` with your delimiter
//write comma separated elements all at once
out.write(resultString);
So here if you have added str1, str2 in the results Vector, then resultString with have value as str1, str2, which you may write at once using your BufferedWriter out.
Also please use Generics in both the sides of initialization as:
Vector<String> results = new Vector<String>();
Related
Suppose csv file contains
1,112,,ASIF
Following code eliminates the null value in between two consecutive commas.
Code provided is more than it is required
String p1=null, p2=null;
while ((lineData = Buffreadr.readLine()) != null)
{
row = new Vector(); int i=0;
StringTokenizer st = new StringTokenizer(lineData, ",");
while(st.hasMoreTokens())
{
row.addElement(st.nextElement());
if (row.get(i).toString().startsWith("\"")==true)
{
while(row.get(i).toString().endsWith("\"")==false)
{
p1= row.get(i).toString();
p2= st.nextElement().toString();
row.set(i,p1+", "+p2);
}
String CellValue= row.get(i).toString();
CellValue= CellValue.substring(1, CellValue.length() - 1);
row.set(i,CellValue);
//System.out.println(" Final Cell Value : "+row.get(i).toString());
}
eror=row.get(i).toString();
try
{
eror=eror.replace('\'',' ');
eror=eror.replace('[' , ' ');
eror=eror.replace(']' , ' ');
//System.out.println("Error "+ eror);
row.remove(i);
row.insertElementAt(eror, i);
}
catch (Exception e)
{
System.out.println("Error exception "+ eror);
}
//}
i++;
}
how to read two consecutive commas from .csv file format as unique value in java.
Here is an example of doing this by splitting to String array. Changed lines are marked as comments.
// Start of your code.
row = new Vector(); int i=0;
String[] st = lineData.split(","); // Changed
for (String s : st) { // Changed
row.addElement(s); // Changed
if (row.get(i).toString().startsWith("\"") == true) {
while (row.get(i).toString().endsWith("\"") == false) {
p1 = row.get(i).toString();
p2 = s.toString(); // Changed
row.set(i, p1 + ", " + p2);
}
...// Rest of Code here
}
The StringTokenizer skpis empty tokens. This is their behavious. From the JLS
StringTokenizer is a legacy class that is retained for compatibility reasons although its use is discouraged in new code. It is recommended that anyone seeking this functionality use the split method of String or the java.util.regex package instead.
Just use String.split(",") and you are done.
Just read the whole line into a string then do string.split(",").
The resulting array should have exactly what you are looking for...
If you need to check for "escaped" commas then you will need some regex for the query instead of a simple ",".
while ((lineData = Buffreadr.readLine()) != null) {
String[] row = line.split(",");
// Now process the array however you like, each cell in the csv is one entry in the array
I have a pretty introductory question that I hope can get answered rather easily.
Currently I am trying to write something that queries my DB, returns result set (list of account id's) and then sets those account id's into an array so that I can populate an object with the values.
My object is going to be used as input into another method I have written but I can't figure out how I go about populating my account_id field on it with the values in my array that I returned in the result set. There doesn't seem to be any "setter" methods for lack of a better term on my array of type String.
I was able to get the array to populate with acct_id's from the result set and print them out so I know that I do have information coming back.
Below is the snippet I currently have, any help/improvements I could make would be greatly appreciated!
try {
connection = DriverManager.getConnection(url, user, password);
st = connection.createStatement();
rs = st.executeQuery(sql);
List<Long> array = new ArrayList<Long>();
while (rs.next()) {
array.add((long) rs.getLong("acct_id"));
for (Integer i = 0; i < array.size(); i++) {
System.out.println(array.get(i));
GetSummaryRequest request = new GetSummaryRequest();
request.accountKey = new AccountDTO(array[i]);
}
}
} catch (SQLException e) {
System.out.println("Connection failed.");
e.printStackTrace();
return;
}
if (rs.next()) {
System.out.println(rs.getString(1));
} else
System.out.print("Failed. Try again");
}
If my understanding is correct you may need the code below which is used to store all the account id's inside an array and you can use this to pass as a parameter to another method.
ArrayList<GetSummaryRequest> array1=new ArrayList<GetSummaryRequest>();
GetSummaryRequest request = new GetSummaryRequest();
while (rs.next())
{
request=new GetSummaryRequest();
request.accountKey=rs.getString("acct_id");
array1.add(request);
}
Now you have ArrayList of GetSummaryRequest with accountKey for each object.
if i understand correctly accountkey is integer right?
you can use Integer.parseint('your string!') class to convert the string to int.
i hope it helps
First of all , storing newline separated values in one column is not a good practice. This is against atomicity principle and will lead you to problems soon - ex., total number of accounts? how do you find it?
Once you convince yourself with this, you can use only one loop like this
List<GetSummaryRequest> summaryRequests = new ArrayList<GetSummaryRequest>();
while (rs.next()) {
String em = rs.getString("acct_id");
GetSummaryRequest request = new GetSummaryRequest();
request.accountKey = em;
summaryRequests.add(request);
}
return summaryRequests;
Probably you need something like that:
// First you get all ids
List<String> accountsIds = new ArrayList<String>();
while (rs.next()) {
accountsIds.add(rs.getString("acct_id"));
}
// Then iterate ids
for (String id : accountsIds) {
GetSummaryRequest request = new GetSummaryRequest();
request.accountKey = id;
}
In my Java code I have embedded a SQL query which fetches data from a database and stores it in a result-set. I want to add a function or a piece of code which will take only non-negative data from the result-set for further processing.
Assumption: The result set can contain positive/negative/zero data values as well as characters. Also i cannot change the SQL query as its out of my scope.
try something like this, i think it will do the job
private ArrayList getNegativeNumbers(ResultSet rs, String coulumnName ) throws SQLException
{
ArrayList ret = new ArrayList();
while(rs.next()){
try {
int x = rs.getInt(coulumnName);
if(x>=0){
ret.add(new Integer(x));
}
} catch (Exception ex) {
String x = rs.getString(coulumnName);
ret.add(x);
}
}
return ret;
}
UPDATED 2. Sorry for my edits, i missread the question
while (resultSet.next()) {
if(resultSet.getInt("Column name") > 0);
Processmethod(resultSet.getInt("Column name") );
}
i have a collection of raw text in a table in database, i need to replace some words in this collection using a set of words.
i put all the term to be replace and its substitutes in a text file as below
min=admin
lelet=lambat
lemot=lambat
nii=nih
ntu=itu
and so on.
i have successfully initiate a variabel of File and Scanner to read the collection of the term and its substitutes.
i loop all the dataset and save the raw text in a string
in the same loop
i loop all the term collection and save its row to a string name 'pattern', and split the pattern into two string named 'term' and 'replacer'
in this loop i initiate a new string which its value is the string from the dataset modified by replaceAll(term,replacer)
end loop for term collection
then i insert the new string to another table in database
end loop for dataset
i do it manualy as below
replaceAll("min","admin")
and its works but its really something to code it manually for almost 2000 terms to be replace it.
anyone ever face this kind of really something..
i really need a help now desperate :(
package sentimenrepo;
import javax.swing.*;
import java.sql.*;
import java.io.*;
//import java.util.HashMap;
import java.util.Scanner;
//import java.util.Map;
/**
*
* #author herman
*/
public class synonimReplaceV2 extends SwingWorker {
protected Object doInBackground() throws Exception {
new skripsisentimen.sentimenttwitter().setVisible(true);
Integer row = 0;
File synonimV2 = new File("synV2/catatan_kata_sinonim.txt");
String newTweet = "";
DB db = new DB();
Connection conn = db.dbConnect("jdbc:mysql://localhost:3306/tweet", "root", "");
try{
Statement select = conn.createStatement();
select.executeQuery("select * from synonimtweet");
ResultSet RS = select.getResultSet();
Scanner scSynV2 = new Scanner(synonimV2);
while(RS.next()){
row++;
String no = RS.getString("no");
String tweet = " "+ RS.getString("tweet");
String published = RS.getString("published");
String label = RS.getString("label");
clean2 cleanv2 = new clean2();
newTweet = cleanv2.cleanTweet(tweet);
try{
Statement insert = conn.createStatement();
insert.executeUpdate("INSERT INTO synonimtweet_v2(no,tweet,published,label) values('"
+no+"','"+newTweet+"','"+published+"','"+label+"')");
String current = skripsisentimen.sentimenttwitter.txtAreaResult.getText();
skripsisentimen.sentimenttwitter.txtAreaResult.setText(current+"\n"+row+"original : "+tweet+"\n"+newTweet+"\n______________________\n");
skripsisentimen.sentimenttwitter.lblStat.setText(row+" tweet read");
skripsisentimen.sentimenttwitter.txtAreaResult.setCaretPosition(skripsisentimen.sentimenttwitter.txtAreaResult.getText().length() - 1);
}catch(Exception e){
skripsisentimen.sentimenttwitter.lblStat.setText(e.getMessage());
}
skripsisentimen.sentimenttwitter.lblStat.setText(e.getMessage());
}
}catch(Exception e){
skripsisentimen.sentimenttwitter.lblStat.setText(e.getMessage());
}
return row;
}
class clean2{
public clean2(){}
public String cleanTweet(String tweet){
File synonimV2 = new File("synV2/catatan_kata_sinonim.txt");
String pattern = "";
String term = "";
String replacer = "";
String newTweet="";
try{
Scanner scSynV2 = new Scanner(synonimV2);
while(scSynV2.hasNext()){
pattern = scSynV2.next();
term = pattern.split("=")[0];
replacer = pattern.split("=")[1];
newTweet = tweet.replace(term, replacer);
}
}catch(Exception e){
e.printStackTrace();
}
System.out.println(newTweet+"\n"+tweet);
return newTweet;
}
}
}
update
ive just realize that the code actually works but only for the first row in database, the second row and so on stand still. here is i update the newest code i ve build
public class synonimReplaceV2 extends SwingWorker {
protected Object doInBackground() throws Exception {
new skripsisentimen.sentimenttwitter().setVisible(true);
Integer row = 0;
String newTweet = "";
DB db = new DB();
Connection conn = db.dbConnect("jdbc:mysql://localhost:3306/tweet", "root", "");
try{
Statement select = conn.createStatement();
select.executeQuery("select * from synonimtweet limit 2,10");
ResultSet RS = select.getResultSet();
FileReader readSyn = new FileReader("synV2/catatan_kata_sinonim.txt");
BufferedReader buffSyn = new BufferedReader(readSyn);
while(RS.next()){
row++;
String no = RS.getString("no");
String tweet = " "+ RS.getString("tweet");
String published = RS.getString("published");
String label = RS.getString("label");
String pattern = "";
while((pattern=buffSyn.readLine())!=null){
String patternTerm = pattern.split("=")[0];
String patternSubs = pattern.split("=")[1];
tweet = tweet.replaceAll("\\s"+patternTerm, patternSubs);
}
try{
Statement insert = conn.createStatement();
insert.executeUpdate("INSERT INTO synonimtweet_v2(no,tweet,published,label) values('"
+no+"','"+tweet+"','"+published+"','"+label+"')");
String current = skripsisentimen.sentimenttwitter.txtAreaResult.getText();
skripsisentimen.sentimenttwitter.txtAreaResult.setText(current+"\n"+row+"original : "+tweet+"\n"+newTweet+"\n______________________\n");
skripsisentimen.sentimenttwitter.lblStat.setText(row+" tweet read");
skripsisentimen.sentimenttwitter.txtAreaResult.setCaretPosition(skripsisentimen.sentimenttwitter.txtAreaResult.getText().length() - 1);
}catch(Exception e){
skripsisentimen.sentimenttwitter.lblStat.setText(e.getMessage());
}
}
}catch(Exception e){
skripsisentimen.sentimenttwitter.lblStat.setText(e.getMessage());
// System.out.println(e.getMessage());
}
Thread.sleep(100);
return row;
}
}
Opening the synonym file and iterating over 2,000 lines for every row in your ResultSet is a bit wasteful.
Load your synonyms into an in-memory Map once, keyed by unique misspelt term, then do a lookup on the map for every row in your result set, and replace as necessary.
Let us use both solutions to build a single solution for you:
First, you create a HashMap with all your keys:
public static HashMap<String, String> getMap() {
//your version would read from the file
HashMap<String,String> myMap=new HashMap<String,String>();
myMap.put("min", "admin");
myMap.put("lelet", "lambat");
myMap.put("lemot", "lambat");
myMap.put("nii", "nih");
myMap.put("ntu", "itu");
return(myMap);
}
Second, you create a pattern that contains all the keys in your hashmap:
public static String getPattern(HashMap<String,String> mapReplacement) {
String pattern="";
for (String s : mapReplacement.keySet()) {
if (!pattern.isEmpty()) {
pattern=pattern+"|";
}
pattern=pattern+s;
}
return(pattern);
}
Next, you can create a cleanTweet method that uses both structures you created:
public static String cleanTweet(String tweet, Pattern pattern,HashMap<String, String> myMap) {
String newTweet=tweet;
Matcher matcher = pattern.matcher(newTweet);
int start=0;
while (matcher.find()) {
String key=matcher.group();
String replacement=myMap.get(key);
if (replacement!=null) {
newTweet=newTweet.replace(key, replacement );
}
}
return(newTweet);
}
This might require some tweaking to perfect (I onyl tested a few cases), but the point is that you are going to iterate a single time in your keys and then iterate only on your tweets.
I hope it helps.
I didn't try, but it seems to me that you've almost got it - just replace this line:
newTweet = tweet.replace(term, replacer);
with this:
tweet = tweet.replaceAll(term, replacer);
As you're not using newTweet any more, return tweet:
return tweet;
You should also delete the newTweet declaration.
Also, you shouldn't read Scanner to read lines. Use FileReader instead.
thanks folks
i ve found the answer why the code is not working,
the txt file containing terms and its substitutes should be initiated each time the program read a row from database.
the code would be like this
public class synonimReplaceV2 extends SwingWorker {
protected Object doInBackground() throws Exception {
new skripsisentimen.sentimenttwitter().setVisible(true);
Integer row = 0;
String newTweet = "";
DB db = new DB();
Connection conn = db.dbConnect("jdbc:mysql://localhost:3306/tweet", "root", "");
try{
Statement select = conn.createStatement();
select.executeQuery("select * from synonimtweet limit 2,10");
ResultSet RS = select.getResultSet();
while(RS.next()){
row++;
FileReader readSyn = new FileReader("synV2/catatan_kata_sinonim.txt");
BufferedReader buffSyn = new BufferedReader(readSyn);
String no = RS.getString("no");
String tweet = " "+ RS.getString("tweet");
String published = RS.getString("published");
String label = RS.getString("label");
String pattern = "";
while((pattern=buffSyn.readLine())!=null){
String patternTerm = pattern.split("=")[0];
String patternSubs = pattern.split("=")[1];
tweet = tweet.replaceAll("\\s"+patternTerm, patternSubs);
}
try{
Statement insert = conn.createStatement();
insert.executeUpdate("INSERT INTO synonimtweet_v2(no,tweet,published,label) values('"
+no+"','"+tweet+"','"+published+"','"+label+"')");
String current = skripsisentimen.sentimenttwitter.txtAreaResult.getText();
skripsisentimen.sentimenttwitter.txtAreaResult.setText(current+"\n"+row+"original : "+tweet+"\n"+newTweet+"\n______________________\n");
skripsisentimen.sentimenttwitter.lblStat.setText(row+" tweet read");
skripsisentimen.sentimenttwitter.txtAreaResult.setCaretPosition(skripsisentimen.sentimenttwitter.txtAreaResult.getText().length() - 1);
}catch(Exception e){
skripsisentimen.sentimenttwitter.lblStat.setText(e.getMessage());
}
}
}catch(Exception e){
skripsisentimen.sentimenttwitter.lblStat.setText(e.getMessage());
// System.out.println(e.getMessage());
}
Thread.sleep(100);
return row;
}
}
but im actually want to apply the code in which rlinden made above, but cant figure it out how to call the cleanTweet function.
I've been working with SQLite on android and I would like to add an arraylist to a column in a table, and then fetch the data back as an arraylist. The arraylist is a list of Longs. I've noticed that SQL has an option for storing BLOBS, however it looks like I need to convert the arraylist to a byte[] first before being able to store it as a blob in my SQLite database.
If anyone has a solution on how to save arraylists into an SQLite database that would be greatly appreciated. Or is there any other option for saving my array of data, i should consider?
To Insert :
ArrayList<String> inputArray=new ArrayList<String>();
//....Add Values to inputArray
Gson gson = new Gson();
String inputString= gson.toJson(inputArray);
System.out.println("inputString= " + inputString);
use "inputString" to save the value of ArrayList in SQLite Database
To retreive:
Get the String from the SQLiteDatabse what you saved and changed into ArrayList type like below:
outputarray is a String which is get from SQLiteDatabase for this example.
Type type = new TypeToken<ArrayList<String>>() {}.getType();
ArrayList<String> finalOutputString = gson.fromJson(outputarray, type);
In SQLite use text as format to store the string Value.....
Please forgive me for savagely plagiarizing my previous answer to BLOB vs. VARCHAR for storing arrays in a MySQL table. The other answers over there are also very pertinent.
I think Con's approach is probably better than using java serialization since java's builtin serialization will need additional bytes, and non-java applications will have a harder time dealing with the data.
public static void storeInDB(ArrayList<Long> longs) throws IOException, SQLException {
ByteArrayOutputStream bout = new ByteArrayOutputStream();
DataOutputStream dout = new DataOutputStream(bout);
for (long l : longs) {
dout.writeLong(l);
}
dout.close();
byte[] asBytes = bout.toByteArray();
PreparedStatement stmt = null; // however you get this...
stmt.setBytes(1, asBytes);
stmt.executeUpdate();
stmt.close();
}
public static ArrayList<Long> readFromDB() throws IOException, SQLException {
ArrayList<Long> longs = new ArrayList<Long>();
ResultSet rs = null; // however you get this...
while (rs.next()) {
byte[] asBytes = rs.getBytes("myLongs");
ByteArrayInputStream bin = new ByteArrayInputStream(asBytes);
DataInputStream din = new DataInputStream(bin);
for (int i = 0; i < asBytes.length/8; i++) {
longs.add(din.readLong());
}
return longs;
}
}
Note: If your lists will sometimes contain more than 31 longs (248 bytes), then you'll need to use BLOB. You cannot use BINARY() or VARBINARY() in MySQL. I realize you're asking about SQLite, but in the spirit of completely plagiarizing my previous answer, I will pretend you're asking about MySQL:
mysql> CREATE TABLE t (a VARBINARY(2400)) ;
ERROR 1074 (42000): Column length too big for column 'a' (max = 255);
use BLOB or TEXT instead
I had two ArrayList<String>, both will 1000+ entries. I looked at blobs and bytes, but for me the solution to speeding up the process and making it usable was by changing the insert method and getting rid of database.insert - Credit for this is here.
private static final String INSERT = "insert into "
+ YOUR_TABLE_NAME+ " (" + COLUMN_1 + ", "
+ COLUMN_2 + ") values (?, ?)";
public void insertArrayData(ArrayList<String> array1,
ArrayList<String> array2) {
try {
database.open();
} catch (SQLException e) {
e.printStackTrace();
}
int aSize = array1.size();
database.beginTransaction();
try {
SQLiteStatement insert = database.compileStatement(INSERT);
for (int i = 0; i < aSize; i++) {
insert.bindString(1, array1.get(i));
insert.bindString(2, array2.get(i));
insert.executeInsert();
}
database.setTransactionSuccessful();
} catch (SQLException e) {
e.printStackTrace();
} finally {
database.endTransaction();
}
try {
database.close();
} catch (Exception e) {
e.printStackTrace();
}
}
It's easily adaptable to Longs and Integers etc and lightening quick. So thankfully I didn't have to scratch my head any longer about blobs and bytes! Hope it helps.
There is an easier way that do such thing in completely another way.
you can make an string that consists of all your array values.
for that make an StringBuilder and append the values continuously and offcource with a separator (like a simbole you which you won't use in your array values . for example virtual '|' .
in code for example :
double[] mylist = new double[]{23, 554, 55};
StringBuilder str = null;
str = new StringBuilder();
for(int i=0;i<mylist.length;i++){
str.append(mylist[i]+"|");
}
String result = str.toString();
db.open();
db.insert(result);
db.close();
when you want to fetch them and use the values. get the column from database pure it to String and with the splite() opration pure each values of array in a column of array than u can easily use it :)
lets do it in code :
String str = db.getdata();
String[] list = str.split("|");
with a simple convert you can use them as double;
double mydouble = Double.parsDouble(list[1].toString());
maybe it is not standard but it is helpfull, hope help ;)
Sounds like you want to serialize the List. Here is a tutorial/intro to the Java Serialization API.
You'll have to do it manually, go through each item in the list and change it to byte before storing it in the database
for (long l : array<long>){
//change to byte here
//Store in database here
}
ArrayList<String> list = new ArrayList<String>();
list.add("Item 1");
list.add("Item 2");
list.add("Item 3");
String joined = TextUtils.join(",", list);
Log.i(TAG, "joined strings: " + joined);
String[] array = TextUtils.split(joined, ",");
Log.i(TAG, "joined strings: " + array[0] + array[1] + array[2]);