I need to add a ResultSet to a list of lists. The string passed to the method is an SQL select statement. The DB connection methods work perfectly with all other methods in this class so that's not the problem here. I know I can replace some of the ArrayList declarations with List but I don't think that matters in this case.
public static ArrayList<ArrayList> selectStatement(String string) throws SQLException {
ArrayList<ArrayList> listOfLists = null;
ArrayList list;
String[] record = null;
try {
rs = null;
dBConnectionOpen();
rs = st.executeQuery(string);
ResultSetMetaData metaData = rs.getMetaData();
int columns = metaData.getColumnCount();
while (rs.next()) {
list = null;
record = new String[columns];
for (int i = 1; i < columns; i++) {
record[i - 1] = rs.getString(i);
}
list = new ArrayList(Arrays.asList(record));
listOfLists.add(list);
}
} catch (Exception e) {
} finally {
dBConnectionClose();
}
return listOfLists;
}
I have done this before, but for some reason it just won't work this time. What am I missing here?
You initialize listOfLists with null value. Try instantiating it from the beginning:
ArrayList<ArrayList> listOfLists = new ArrayList<ArrayList>();
Also, it would be better:
Use List interface instead of plain ArrayList class implementation
Use List<String> instead of raw List.
Instead of using String[] record, save the data directly in the List<String>.
Keep the variable scope as short as possible. List<String> list can be directly inside the while loop.
Knowing this, the code can change to:
List<List<String>> listOfLists = new ArrayList<List<String>>();
...
while (rs.next()) {
List<String> list = new ArrayList<String>();
for (int i = 1; i < columns; i++) {
list.add(rs.getString(i));
}
listOfLists.add(list);
}
More info:
What does it mean to "program to an interface"?
Related
I have to get 'tags' from the database and store them in an array so I could check if my document contains them. Due to the number of tag categories (customers, system_dependencies, keywords) I have multiple arrays to compare my document with. Is there an easy way to simplify and make my code look nicer?
This is my approach but it looks terrible with all the repetitive for loops.
ArrayList<String> KEYWORDS2 = new ArrayList<String>();
ArrayList<String> CUSTOMERS = new ArrayList<String>();
ArrayList<String> SYSTEM_DEPS = new ArrayList<String>();
ArrayList<String> MODULES = new ArrayList<String>();
ArrayList<String> DRIVE_DEFS = new ArrayList<String>();
ArrayList<String> PROCESS_IDS = new ArrayList<String>();
while (resultSet2.next()) {
CUSTOMERS.add(resultSet2.getString(1));
}
sql = "SELECT da_tag_name FROM da_tags WHERE da_tag_type_id = 6";
stmt = conn.prepareStatement(sql);
resultSet2 = stmt.executeQuery();
while (resultSet2.next()) {
SYSTEM_DEPS.add(resultSet2.getString(1));
}
while (resultSet.next()) {
String da_document_id = resultSet.getString(1);
String file_name = resultSet.getString(2);
try {
if(file_name.endsWith(".docx") || file_name.endsWith(".docm")) {
System.out.println(file_name);
XWPFDocument document = new XWPFDocument(resultSet.getBinaryStream(3));
XWPFWordExtractor wordExtractor = new XWPFWordExtractor(document);
//Return what's inside the document
System.out.println("Keywords found in the document:");
for (String keyword : KEYWORDS) {
if (wordExtractor.getText().contains(keyword)) {
System.out.println(keyword);
}
}
System.out.println("\nCustomers found in the document:");
for (String customer : CUSTOMERS) {
if (wordExtractor.getText().contains(customer)) {
System.out.println(customer);
}
}
System.out.println("\nSystem dependencies found in the document:");
for (String systemDeps : SYSTEM_DEPS) {
if (wordExtractor.getText().contains(systemDeps)) {
System.out.println(systemDeps);
}
}
System.out.println("Log number: " + findLogNumber(wordExtractor));
System.out.println("------------------------------------------");
wordExtractor.close();
}
As you can see there are 3 more to come and this doesn't look good already. Maybe there's a way to compare all of them at the same time.
I have made another attempt at this creating this method:
public void genericForEachLoop(ArrayList<String> al, POITextExtractor te) {
for (String item : al) {
if (te.getText().contains(item)) {
System.out.println(item);
}
}
}
Then calling it like so: genericForEachLoop(MODULES, wordExtractor);
Any better solutions?
I've got two ideas to shorten this: first of all you can write a general for-loop in a separate method that has an ArrayList as a parameter. Then you pass it each of your ArrayLists successively, which would mean that at least you do not have to repeat the for-loops. Secondly, you can create an ArrayList of type ArrayList and store your ArrayLists inside it. Then you can iterate over the whole thing. Only apparent disadvantage of both ideas (or a combination of them) would be, that you need to name the variable for your query string alike for the search of each ArrayList.
What you could do is use a Map and an enum like this:
enum TagType {
KEYWORDS2(2), // or whatever its da_tag_type_id is
CUSTOMERS(4),
SYSTEM_DEPS(6),
MODULES(8),
DRIVE_DEFS(10),
PROCESS_IDS(12);
public final daTagTypeId; // this will be used in queries
TagType(int daTagTypeId) {
this.daTagTypeId = daTagTypeId;
}
}
Map<TagType, List<String>> tags = new HashMap<>();
XWPFDocument document = new XWPFDocument(resultSet.getBinaryStream(3));
XWPFWordExtractor wordExtractor = new XWPFWordExtractor(document);
for(TagType tagType : TagType.values()) {
tags.put(tagType, new ArrayList<>()); // initialize
String sql = String.format("SELECT da_tag_name FROM da_tags WHERE da_tag_type_id = %d", tagType.daTagTypeId); // build query
stmt = conn.prepareStatement(sql);
resultSet2 = stmt.executeQuery();
while(resultSet2.next()) { // fill from DB
tags.get(tagType).add(.add(resultSet2.getString(1)));
}
System.out.println(String.format("%s found in the document:", tags.get(tagType).name());
for (String tag : tags.get(tagType)) { // search in text
if (wordExtractor.getText().contains(tag)) {
System.out.println(keyword);
}
}
}
But at this point I'm not sure you need those lists at all:
enum TagType {
KEYWORDS2(2), // or whatever its da_tag_type_id is
CUSTOMERS(4),
SYSTEM_DEPS(6),
MODULES(8),
DRIVE_DEFS(10),
PROCESS_IDS(12);
public final daTagTypeId; // this will be used in queries
TagType(int daTagTypeId) {
this.daTagTypeId = daTagTypeId;
}
}
XWPFDocument document = new XWPFDocument(resultSet.getBinaryStream(3));
XWPFWordExtractor wordExtractor = new XWPFWordExtractor(document);
for(TagType tagType : TagType.values()) {
String sql = String.format("SELECT da_tag_name FROM da_tags WHERE da_tag_type_id = %d", tagType.daTagTypeId); // build query
stmt = conn.prepareStatement(sql);
resultSet2 = stmt.executeQuery();
System.out.println(String.format("%s found in the document:", tags.get(tagType).name());
while(result2.next()) {
String tag = resultSet2.getString(1);
if (wordExtractor.getText().contains(tag)) {
System.out.println(keyword);
}
}
}
This given I don't know where those resultSet is declared and initialised, nor where that resultSet2 is initialised.
Basically you just fetch tags for each type from DB and then directly search them in the text without storing them at first and then re-iterating the stored ones... I mean that's what the DB is there for.
My question is when i store the data into array from sqlite database, how can i get it from specific position let say, my database contain "food, drinks,snack" how can i get the string "snack" from array.
String CatNameQuery = "SELECT * FROM Category";
db = new DBController(MainActivity.this);
SQLiteDatabase db3 = db.getReadableDatabase();
final Cursor cursor2 = db3.rawQuery(CatNameQuery, null);
{
List<String> array = new ArrayList<String>();
while(cursor2.moveToNext()){
String uname = cursor2.getString(cursor2.getColumnIndex("CategoryName"));
array.add(uname);
}
You need to iterate through the list in order to find the item you are looking for.
For example:
for (String s : array) {
if (s.equals("snack")) {
System.out.println("Found snack");
}
}
You can also use the contains method to check if the list contains "snack."
if (array.contains("snack")) {
System.out.println("Found snack");
}
Resource: ArrayList
Use the WHERE clause within your SELECT query. For example:
"SELECT * FROM Category WHERE CategoryName='snacks'"
This will fill your array with only items under the category 'snacks'.
List<String> array = new ArrayList<String>();
array.add("food");
array.add("drinks");
array.add("snack");
String result="";
if (array.contains("snack")) // avoid null pointer exception
{
int index =array.indexOf("snack") //find the index of arraylist
result=array.get(index);
}
You can find it by looping the array
List<String> arrobj= new ArrayList<String>();
arrobj.add("food");
arrobj.add("drinks");
arrobj.add("snack");
for (String value : arrobj) {
if (value.equals("snack")) {
System.out.println("Here is the snack");
}
}
if (array.size() > 0) {
int index = 0;
if (array.contains("Snacks")) {
index = array.indexOf("Snacks");
System.out.println(array.get(index));
}
}
I am trying to create a method that will update a list that has already been created. Im not sure why this is not working?
It throws a null pointer exception.
This is my code:
private void UpdateJList(){
String query = "SELECT * FROM names WHERE TYA=?";
String partialSearch = "Sales";
try{
connect.pst = connect.con.prepareStatement(query);
connect.pst.setString(1, partialSearch);
connect.pst.execute();
ArrayList<String> add = new ArrayList<String>();
String[] items = {};
while (connect.rs.next()){
String result = connect.rs.getString("ACNO");
add.add(result);
int length = add.size();
DefaultListModel<String> model;
model = new DefaultListModel<String>();
for (int i=0; i<length; i++){
model.add(i, result);
}
jList1.setModel(model);
jList1.setSelectedIndex(0);
}
}catch(Exception e){
JOptionPane.showMessageDialog(null, e);
}
}
Thank you in advance!!
There are 2 major problems with that code:
In the while loop, you are creating many instances of DefaultListModel. That means, for each entry of the query result, you are restarting the list.
A nullpointer exception is produced by the line: connect.rs.next() because you didn't assign connect.rs with the query's resultset.
I want to modify an existing *.rptdesign file and save it under a new name.
The existing file contains a Data Set with a template SQL select statement and several DS parameters.
I'd like to use an actual SQL select statement which uses only part of the DS parameters.
However, the following code results in the exception:
Exception in thread "main" `java.lang.RuntimeException`: *The structure is floating, and its handle is invalid!*
at org.eclipse.birt.report.model.api.StructureHandle.getStringProperty(StructureHandle.java:207)
at org.eclipse.birt.report.model.api.DataSetParameterHandle.getName(DataSetParameterHandle.java:143)
at org.eclipse.birt.report.model.api.DataSetHandle$DataSetParametersPropertyHandle.removeParamBindingsFor(DataSetHandle.java:851)
at org.eclipse.birt.report.model.api.DataSetHandle$DataSetParametersPropertyHandle.removeItems(DataSetHandle.java:694)
--
OdaDataSetHandle dsMaster = (OdaDataSetHandle) report.findDataSet("Master");
HashSet<String> bindVarsUsed = new HashSet<String>();
...
// find out which DS parameters are actually used
HashSet<String> bindVarsUsed = new HashSet<String>();
...
ArrayList<OdaDataSetParameterHandle> toRemove = new ArrayList<OdaDataSetParameterHandle>();
for (Iterator iter = dsMaster.parametersIterator(); iter.hasNext(); ) {
OdaDataSetParameterHandle dsPara = (OdaDataSetParameterHandle)iter.next();
String name = dsPara.getName();
if (name.startsWith("param_")) {
String bindVarName = name.substring(6);
if (!bindVarsUsed.contains(bindVarName)) {
toRemove.add(dsPara);
}
}
}
PropertyHandle paramsHandle = dsMaster.getPropertyHandle( OdaDataSetHandle.PARAMETERS_PROP );
paramsHandle.removeItems(toRemove);
What is wrong here?
Has anyone used the DE API to remove parameters from an existing Data Set?
I had similar issue. Resolved it by calling 'removeItem' multiple times and also had to re-evaluate parametersIterator everytime.
protected void updateDataSetParameters(OdaDataSetHandle dataSetHandle) throws SemanticException {
int countMatches = StringUtils.countMatches(dataSetHandle.getQueryText(), "?");
int paramIndex = 0;
do {
paramIndex = 0;
PropertyHandle odaDataSetParameterProp = dataSetHandle.getPropertyHandle(OdaDataSetHandle.PARAMETERS_PROP);
Iterator parametersIterator = dataSetHandle.parametersIterator();
while(parametersIterator.hasNext()) {
Object next = parametersIterator.next();
paramIndex++;
if(paramIndex > countMatches) {
odaDataSetParameterProp.removeItem(next);
break;
}
}
if(paramIndex < countMatches) {
paramIndex++;
OdaDataSetParameter dataSetParameter = createDataSetParameter(paramIndex);
odaDataSetParameterProp.addItem(dataSetParameter);
}
} while(countMatches != paramIndex);
}
private OdaDataSetParameter createDataSetParameter(int paramIndex) {
OdaDataSetParameter dataSetParameter = StructureFactory.createOdaDataSetParameter();
dataSetParameter.setName("param_" + paramIndex);
dataSetParameter.setDataType(DesignChoiceConstants.PARAM_TYPE_INTEGER);
dataSetParameter.setNativeDataType(1);
dataSetParameter.setPosition(paramIndex);
dataSetParameter.setIsInput(true);
dataSetParameter.setIsOutput(false);
dataSetParameter.setExpressionProperty("defaultValue", new Expression("<evaluation script>", ExpressionType.JAVASCRIPT));
return dataSetParameter;
}
Adding the colums works, but i am stuck when i want to add the data of the columns stored in a mysql database to the jtable. it ask for a object vector[][] but i have no clue what to give
Connection con;
DefaultTableModel model = new DefaultTableModel();
public Hoofdscherm() {
initComponents();
uitvoerSpelers.setModel(model);
try {
con = DriverManager.getConnection("jdbc:mysql://localhost/fullhouse", "root", "hamchi50985");
// selecteer gegevens uit fullhouse.speler tabel
PreparedStatement stat = con.prepareStatement("SELECT * FROM fullhouse.speler");
// sla deze GEGEVENS op in een resultset
ResultSet resultaat = stat.executeQuery();
// haal alle kolomnamen op PUUR VOOR DE MODEL VAN JTABLE
ResultSetMetaData data = resultaat.getMetaData();
String[] colum = new String[15];
for (int i = 1; i < data.getColumnCount(); i++) {
colum[i] = data.getColumnName(i);
model.addColumn(colum[i]);
while (resultaat.next()) {
Object[] gegevens = new String[] {resultaat.getString(1)};
model.addRow(gegevens[0]);
}
}
} catch (SQLException ex) {
JOptionPane.showMessageDialog(null, ex);
}
}
I think you need something like this.
Note
1. Also add your columns separate to resultset data. Like I showed in my code below.
Vector<String> rowOne = new Vector<String>();
rowOne.addElement("R1C1");
rowOne.addElement("R1C2");
Vector<String> rowTwo = new Vector<String>();
rowTwo.addElement("R2C1");
rowTwo.addElement("R2C2");
Vector<String> cols = new Vector<String>();
Vector<Vector> vecRow = new Vector<Vector>();
vecRow.addElement(rowOne);
vecRow.addElement(rowTwo);
cols.addElement("Col1");
cols.addElement("Col2");
JTable table = new JTable(vecRow, cols);
Edit
For you convenience and requirement You can follow code structure below.
Vector<String> rows = new Vector<String>();
Vector<Vector> dBdata = new Vector<Vector>();
// Add Columns to table
for (int i = 1; i < data.getColumnCount(); i++) {
colum[i] = data.getColumnName(i);
model.addColumn(colum[i]);
}
while (resultaat.next()) {
// add column data to rows vector
// Make sure that all data type is in string because of generics
rows.add(resultaat.getString("columnName1"));
rows.add(resultaat.getString("columnName2"));
rows.add(resultaat.getString("columnName3"));
// add whole row vector to dBdata vector
dBdata.addElement(rows);
}
model.addRow(dBdata);
Vector implements a dynamic array. It is similar to ArrayList, but with two differences:
Vector is synchronized.
Vector contains many legacy methods that are not part of the collections framework.
Class Vector Javadoc
I hope this will help you.
The line model.addRow(gegevens[0]);is incorrect.
You should do something like this:
String[] colum = new String[15];
for (int i = 1; i < data.getColumnCount(); i++) {
colum[i] = data.getColumnName(i);
model.addColumn(colum[i]);
while (resultaat.next()) {
Object[] gegevens = new String[] {resultaat.getString(1)};
model.addRow(gegevens);
}
}
Also you need to check DefaultTableModel
According to the documentation of DefaultTableModel:
This is an implementation of TableModel that uses a Vector of Vectors
to store the cell value objects.