JarCastingColumn Table Model
Introduction
ColumnTableModel is an extension of AbstractTableModel that reorganizes the data and functions that conceptually belong to a column.
Using AbstractTableModel, a simple table can be implemented like this:
public class StringsTableModel extends AbstractTableModel {
private final List<String> data=new ArrayList<>();
@Override
public int getColumnCount() {
return 3;
}
@Override
public Object getColumnName(int col) {
switch (col) {
case 0: return "Index";
case 1: return "String";
case 2: return "Hash";
default: throw new IndexOutOfBoundsException();
}
}
@Override
public Object getValueAt(int row, int col) {
switch (col) {
case 0: return row+1;
case 1: return data.get(row);
case 2: return data.get(row).hashCode();
default: throw new IndexOutOfBoundsException();
}
}
@Override
public Object getColumnClass(int col) {
switch (col) {
case 0: return Integer.class;
case 1: return String.class;
case 2: return Integer.class;
default: throw new IndexOutOfBoundsException();
}
}
@Override
public boolean isCellEditable(int row, int col) {
return col==1;
}
@Override
public void setValueAt(Object value, int row, int col) {
if (col==1) {
data.set(row, (String)value);
fireTableRowsUpdated(row, row);
}
}
}
Especially when the model contains more columns, this code becomes hard to maintain. The columns are identified by their indices, and data belonging to a particular column is spread over several functions. For example, changing the order of the columns requires rewriting a lot of indices in the model functions; it is easy to make a mistake.
Example
ColumnTableModel groups the code belonging to each column into a Column class. The following example class implements the same model as the above, but using ColumnTableModel:
public class StringsTableModel extends ColumnTableModel {
private final List<String> data=new ArrayList<>();
public final Column indexColumn=new Column("Index", Integer.class) {
@Override
public Object get(int row) {
return row+1;
}
};
public final Column stringColumn=new Column("Value", String.class, true) {
@Override
public Object get(int row) {
return data.get(row);
}
@Override
public void set(Object value, int row) {
data.set(row, (String)value);
fireTableRowsUpdated(row, row);
}
};
public final Column hashColumn=new Column("Hash", Integer.class) {
@Override
public Object get(int row) {
return data.get(row).hashCode();
}
};
public StringsTableModel() {
addColumns(indexColumn, stringColumn, hashColumn);
}
@Override
public int getRowCount() {
return data.size();
}
}
Using
The library resides in the central Maven repository with group ID hu.kazocsaba and artifact ID column-table-model. If you use a project management system which can fetch dependencies from there, you can just add the library as a dependency. E.g. in Maven:
<dependency>
<groupId>hu.kazocsaba</groupId>
<artifactId>column-table-model</artifactId>
<version>1.0.0</version>
</dependency>
You can also browse the online javadoc.