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Changing colour of specific cell in a JTable

I'm trying to change the colour of one or more particular cells in a column in my JTable. The answers I have seen on here all refer to this particular method;
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column)
{
Component y = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
y.setBackground(new Color(255,0,0));
return y;
}
But the problem is I do not understand in any way how this works, in my other class I have a Jtable of strings and I want to change the colour of certain cells according to their string value, however the solutions i find only allow me to change the colour of an entire column of cells in the jtable and not a specific one.

I have a Jtable of strings and I want to change the colour of certain cells according to their string value
The same renderer is used for all cells so you need to reset the background every time.
You will need an if condition in your custom renderer code. Something like:
if (!isSelected)
if (value.equals(...))
y.setBackground(new Color(255,0,0));
else
y.setBackground(table.getBackground())

You can use DefaultTableCellRenderer to color alternate row from JTable.
table.setDefaultRenderer(Object.class, new TableCellRenderer(){
private DefaultTableCellRenderer DEFAULT_RENDERER = new DefaultTableCellRenderer();
#Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
Component c = DEFAULT_RENDERER.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
if(isSelected){
c.setBackground(Color.YELLOW);
}else{
if (row%2 == 0){
c.setBackground(Color.WHITE);
}
else {
c.setBackground(Color.LIGHT_GRAY);
} }
//Add below code here
return c;
}
});
If you want to color your row using the value of a particular row then you can use something like this. Add these line to above
if(table.getColumnModel().getColumn(column).getIdentifier().equals("Status")){//Here `Status` is column name
if(value.toString().equals("OK")){//Here `OK` is the value of row
c.setBackground(Color.GREEN);
}
}

Jtable, use different alignment for each ROW

I have created a table and need to align every second row to the right, and every other row to default.
I understand how to align the rows. This is my default renderer
final DefaultTableCellRenderer centerRenderer = new DefaultTableCellRenderer();
centerRenderer.setHorizontalAlignment(DefaultTableCellRenderer.CENTER);
final DefaultTableCellRenderer rightRenderer = new DefaultTableCellRenderer();
rightRenderer.setHorizontalAlignment(DefaultTableCellRenderer.RIGHT);

You'll have to tweak the renderer a little and override its getTableCellRendererComponent method. Something like:
DefaultTableCellRenderer renderer = new DefaultTableCellRenderer() {
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column) {
if (r % 2 == 0) {
setHorizontalAlignment(SwingConstants.LEFT);
}
else {
setHorizontalAlignment(SwingConstants.RIGHT);
}
return super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
}
};
Although creating your own proper class that extends DefaultTableCellRenderer and does this would be a better approach.

See Table Row Rendering.
This will allow you to change the alignment in one place even if your table uses multiple renderers and without creating a custom renderer.

JTable CustomRenderer Issue

I have created one Jtable.This table consist of two columns name and timestamp. I want to make color of row yellow if name is "jane". Following is the code for that :-
class CustomRenderer extends DefaultTableCellRenderer {
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
Component c = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
String name = table.getModel().getValueAt(row, 0).toString();
if (name.trim().equals("jane")) {
c.setBackground(Color.YELLOW);
}
return c;
}
}
However instead of changing color of row to yellow for particular name, it is changing color of every row.I am setting data of table as following
tableModelName = (DefaultTableModel)jTableName.getModel();
jTableName.setDefaultRenderer(Object.class,new CustomRenderer());
for(int i=0; i<records.size(); i++)
{
tableModelName.addRow(records.get(i));
}
What I am doing wrong ?

You need an else clause to set the background color to something besides yellow if the name is not "jane". A single renderer instance is used for all rendering, so once you set the color to yellow on that instance, it stays yellow.
Take a look at the JTable source code to see how the built-in renderers work:
if (isSelected) {
setForeground(table.getSelectionForeground());
super.setBackground(table.getSelectionBackground());
}
else {
setForeground(table.getForeground());
setBackground(table.getBackground());
}
For an easier way of doing this, you might try subclassing JTable and overriding prepareRenderer. This is handy for changes that affect entire rows like this, so you can use custom renderers for the individual cells, and tweak all renderers for a row in the prepareRenderer method.

Change the color of some rows but not all in a JTable

I have created a custom cell renderer class to achieve this.
public class MatchTableCellRenderer extends DefaultTableCellRenderer{
public Component getTableCellRendererComponent (JTable table,
Object obj, boolean isSelected, boolean hasFocus, int row, int column) {
Component cell;
cell = super.getTableCellRendererComponent(
table, obj, isSelected, hasFocus, row, column);
if( ((String[]) ((MatchTableModel) table.getModel()).getRow(row)).length==7 ){
System.out.println(((String[]) ((MatchTableModel) table.getModel()).getRow(row))[0]+" "+((String[]) ((MatchTableModel) table.getModel()).getRow(row))[6]);
cell.setForeground(Color.green);
}
return cell;
}
}
And I have set this renderer to be used by my table's columns:
tempColumn = table.getColumnModel().getColumn(0);
tempColumn.setCellEditor(new MacColumnEditor());
tempColumn.setCellRenderer(new MatchTableCellRenderer());
tempColumn = table.getColumnModel().getColumn(1);
tempColumn.setCellEditor(new IpColumnEditor());
tempColumn.setCellRenderer(new MatchTableCellRenderer());
tempColumn = table.getColumnModel().getColumn(2);
DefaultCellEditor dfEditor=new DefaultCellEditor(new JTextField());
dfEditor.setClickCountToStart(2);
tempColumn.setCellEditor(dfEditor);
tempColumn.setCellRenderer(new MatchTableCellRenderer());
I want the rows which contain a String[] of length=7 green and the others with the default color. But it is interesting that all my rows become green. I have a print line as you can see. It is printed 4 times (my table has 12 rows), but all rows are made green, instead of 4. What am I doing wrong?

The reason is the infamous color memory (TM) of the DefaultTableCellEditor: you have to set the colors always, instead of only in one branch.
if (myCondition) {
setBackground(...) {
} else {
setBackground(...)
}
the exact details are explained in a recent thread

You can use XxxCellRenderer, but better and easiest is to use prepareRenderer()
for correct code you have to override or test inside if-else follows patameters
isSelected
hasFocus
column
row
more in answers and question about similair issue

How can I focus on a whole row of a JTable?

I have a JTable that is showing some records in a Java Swing application. The user only works with whole rows, not with individual cells. Is there any way I can focus on a whole row of a JTable? The default is to focus only the cell that the user has clicked on. I use a different color for the focus, so it doesn't look good if only a cell is focused instead of the whole row.
UPDATE: This is my current code of my custom TableCellRenderer, the issue is that when a row has focus and is painted with the "focus" color, and then the JTable loses focus, only the cell that had focus is repainted with the "selected" color but all cells in the selected row should be repainted with the "selected" color.
#Override
public Component getTableCellRendererComponent(JTable table,
Object value, boolean isSelected, boolean hasFocus,
int row, int column) {
// Has any cell in this row focus?
if(table.getSelectedRow() == row && table.hasFocus()) {
hasFocus = true;
}
if (hasFocus) {
this.setBackground(CustomColors.focusedColor);
} else if (isSelected) {
this.setBackground(CustomColors.selectedColor);
} else {
// alternate the color of every second row
if(row % 2 == 0) {
this.setBackground(Color.WHITE);
} else {
this.setBackground(CustomColors.grayBg);
}
}
setValue(value);
return this;
}

Sounds like you're looking for the setRowSelectionAllowed() method.
Since you said just changing the color would be sufficient, you might want to look at the custom cell renderer section of the Swing Tutorial. You'd just have to set the logic to check on whether a given cell was in a selected row, and paint the background color accordingly.

A first idea would be something like
JTable jTable = new JTable() {
public TableCellRenderer getCellRenderer(int row, int column) {
final TableCellRenderer superRenderer = super.getCellRenderer(row, column);
return new TableCellRenderer() {
#Override
public Component getTableCellRendererComponent(JTable table, Object object, boolean isSelected, boolean hasFocus, int row, int column) {
// determine focus on row attribute only
hasFocus = hasFocus() && isEnabled() && getSelectionModel().getLeadSelectionIndex() == row;
return superRenderer.getTableCellRendererComponent(table, object, isSelected, hasFocus, row, column);
}
};
}
};
where I use my own logic to determine the focus based on the row attribute only. It uses the underlying cell renderers but looks strange if focus border is used.