Why does my Java custom cell renderer not show highlighting when the row/cell is selected?

问题:

I have a custom cell renderer for a cell to do a word wrap so more content can be read. Here is the code:

import java.awt.Color; import java.awt.Component; import java.awt.Insets;  import javax.swing.JTable; import javax.swing.JTextArea; import javax.swing.table.TableCellRenderer;  public class TextWrapCellRenderer extends JTextArea implements TableCellRenderer {     private static final long serialVersionUID = 1L;      public TextWrapCellRenderer() {         setLineWrap(true);         setWrapStyleWord(true);         setMargin(new Insets(0, 5, 0, 5));         setSelectionColor(Color.GREEN);     }      public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {         setText((String)value);         setSize(table.getColumnModel().getColumn(column).getWidth(),getPreferredSize().height);         setSelectionColor(Color.GREEN);          return this;     } } 

Update: The cell renderer is used properly but when the user selects a row in the JTable, then it only shows the highlighting for the non-custom rendered cells. The highlighting shows for all other cells for that row though. This leaves just one cell with a white background while the rest of the row has blue (in my case) as the highlighted background color.

回答1:

You have to check the isSelected argument to see if the cell is selected or not, something like:

public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column)  {         setText((String)value);         setSize(table.getColumnModel().getColumn(column).getWidth(),getPreferredSize().height);         setSelectionColor(Color.GREEN);          if (isSelected)         {             setBackground(table.getSelectionBackground());             setForeground(table.getSelectionForeground());         }         else         {             setBackground(table.getBackground());             setForeground(table.getForeground());         }         return this;     } 

回答2:

I think you should call the default implementation first:

public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {     super.getTableCellRendererComponent(table,value,isSelected,hasFocus,row,column);     ... 

The default implementation will process all usual arguments such as isSelected and hasFocus, set the text and background color, activate the focus border etc. Then you will change the displayed text, change the cell size and return this.

回答3:

Using setSelectionColor(Color.GREEN); you are telling just what user select is green. What's is your problem and what you expect your code to do?

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