1. CompSci 280 S2 2107 Introduction to Software Development
GUI 2

2. Today’s Agenda Topics: Java Python JList, JComboBox
DefaultListModel
DefaultComboBoxModel
JTable & TableModel
DefaultTableMode
implements the AbstractTableModel
Event Handling
Python
QListView
QAbstractListModel
QTableView
QAbstractTableModel
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3. Java MVC Example Example: JList
Example: PhilosophersJList.java
<<interface>>
Javax.swing.ListModel
Javax.swing.JList
Add/remove items
notifies
<<abstract>>
AbstractListModel
modifies
DefaultListModel
DefaultListModel
Javax.swing.JComponent
isEmpty(): boolean
getSize(): int
addElement(Object)
removeElement(Object)
elementAt(): Object
removeElementAt(int)
insertElementAt(int)
indexOf(Object): int
etc
JList
Example: JList
A ListModel is an object which maintains a list of objects: it knows how big the list is, which object is where in the list, etc, and can insert/remove objects
A JList is a graphical component giving a view of the list and able to receive user input to modify the list
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4. Java Creating a Model (List and Combo Box)
To create a list model:
DefaultListModel — everything is pretty much taken care of for you.
ListModel — create a new class which implements the ListModel interface and implement the getSize and getElementAt methods
To create a combo box model:
DefaultComboBoxModel — everything is pretty much taken care of for you.
ComboBoxModel — create a new class which implements the ComboBoxModel interface and implement the setSelectedItem and getSelectedItem methods
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5. Example: MV_ComboBoxDemo.java
Java Examples
Example: MV_ComboBoxDemo.java
DefaultComboBoxModel:
DefaultListModel:
JComboBox<String> ppComboBox;
...
DefaultComboBoxModel<String> cbm = new DefaultComboBoxModel<String>( new String[]
{ "person", "student", "employee" });
ppComboBox = new JComboBox<String>(cbm);
creates a mutable list model object, puts the initial items in it, and uses the list model to create a list:
JList<String> list;
...
DefaultListModel<String> listModel = new DefaultListModel<String>();
listModel.addElement("red");
listModel.addElement("orange");
listModel.addElement("yellow");
list = new JList<String>(listModel);
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6. import java.swingx.table.*;
Java Using JTable
Tables are used to display data in a spreadsheet fashion
So key concepts in the model of a table:
cell, row, column
Value(s) in each
Every table gets its data from an object that implements the TableModel interface
You can use the DefaultTableModel, OR
You an create a new class which implements the AbstractTableModel interface and implements the following methods:
getColumnName
getRowCount
getColumnCount
getValueAt
import java.swingx.table.*;
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7. Java Using the DefaultTableModel
Example: DefaultTableModelDemo.java
Model might hold its data in an array, vector or from an database
Object[][] data = { {"Mary", "Campione","Snowboarding", new Integer(5) ...}
{"Alison", "Huml","Rowing", new Integer(3), new Boolean(true)} ...};
String[] columnNames = {"First Name","Last Name","Sport","# of Years","Vegetarian"};
DefaultTableModel defaultTableModel = new DefaultTableModel(data, columnNames);
...
table = new JTable(defaultTableModel);
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8. Java Using the AbstractTableModel
Example: AbstractTableModelDemo.java
Steps in creating and using AbstractTableModel
Create an AbstractTableModel subclass
Implement the getRowCount() , getColumnCount() , and getValueAt() methods
JTable table = new JTable(new AbstractTableModel() {
public int getColumnCount() { return 10; }
public int getRowCount() { return 5;}
public Object getValueAt(int row, int col) {
return new Integer((row+1)*(col+1)); }
});
getContentPane().add(table, BorderLayout.CENTER);
extends AbstractTableModel
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9. Example: DefaultTableModelDemo.java
Java Controller
Example: DefaultTableModelDemo.java
A controller that takes user input on the view and translates that to changes in the model.”
Example:
You do NOT directly update JTable, T
Instead, you update the TableModel, TM, which automatically updates the Table, T
changeButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
DefaultTableModel tm = (DefaultTableModel) table.getModel();
for (int row=0; row<tm.getRowCount(); row++) {
int years = (Integer) tm.getValueAt(row, 3);
tm.setValueAt(years+1, row, 3); }
});
Change the TableModel
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10. Java Example Update the ListModel
addButton.addActionListener( new ActionListener() {
public void actionPerformed( ActionEvent event ) {
String name = JOptionPane.showInputDialog(PhilosophersJList.this, "Enter Name" );
philosophers.addElement( name ); }
});
Change the ListModel
removeButton.addActionListener( new ActionListener() {
public void actionPerformed( ActionEvent event ) {
philosophers.removeElement(list.getSelectedValue() ); }
});
Change the ListModel
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11. MVC Example in Pyton
QListView: Provides a selectable list of items in ListMode
QComboBox: Provides a dropdown list of items to select from
QTableView: provides a default model/view implementation of a table.
lm = MyListModel(list_data, self)
lv = QListView()
lv.setModel(lm)
tablemodel = MyTableModel(my_array, self)
tableview = QTableView()
tableview.setModel(tablemodel)
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12. Python Creating Models
QAbstractListModel – for single-column lists
QAbstractListModel provides a standard interface for models that represent their data as a simple non-hierarchical sequence of items.
It is not used directly, but must be subclassed
QAbstractTableModel – for tables
QAbstractTableModel provides a standard interface for models that represent their data as a two-dimensional array of items.
It is not used directly, but must be subclassed.
It can be subclassed to create table models.
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13. Python QAbstractListModel
Example: PhilosophersJList.py
Create a new class which extends the QAbstractListModel and implement the following methods:
Constructor
rowCount: return the number of items in the list
data:  to retrieve items from the list.
class MyListModel(QAbstractListModel):
def __init__(self, datain, parent=None, *args):
QAbstractListModel.__init__(self, parent, *args)
self.listdata = datain
def rowCount(self, parent):
return len(self.listdata)
def data(self, index, role):
if index.isValid() and role == Qt.DisplayRole:
return QVariant(self.listdata[index.row()])
else:
return QVariant()
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14. Python QAbstractTableModel
Example: TableModelDemo.py
Create a new class which extends the QAbstractTableModel and implement the following methods:
Constructor
The rowCount() and columnCount() functions return the dimensions of the table
data:  to retrieve items from the table.
headerData
class MyTableModel(QAbstractTableModel):
def __init__(self, datain, parent=None, *args):
QAbstractTableModel.__init__(self, parent, *args)
self.arraydata = datain
def rowCount(self, parent):
return len(self.arraydata)
def columnCount(self, parent):
return len(self.arraydata[0])
def data(self, index, role):
if not index.isValid():
return QVariant()
elif role != Qt.DisplayRole:
return QVariant(self.arraydata[index.row()][index.column()])
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15. Python Modifying Models
A model can change for a number of reasons
Modifying Structure
Inserting and removing rows and columns must be communicated from the model, the layoutChanged signal must be emitted
class MyTableModel(QAbstractTableModel):
self.arraydata = ...
self.layoutChanged.emit()
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