GWT - FlexTable Widget


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Introduction

The FlexTable widget represents a flexible table that creates cells on demand. It can be jagged (that is, each row can contain a different number of cells) and individual cells can be set to span multiple rows or columns.

Class Declaration

Following is the declaration for com.google.gwt.user.client.ui.FlowPanel class −

public class FlexTable
   extends HTMLTable

Class Constructors

Sr.No. Constructor & Description
1

FlexTable()

Constructor for empty Flex Table.

Class Methods

Sr.No. Function name & Description
1

void addCell(int row)

Appends a cell to the specified row.

2

int getCellCount(int row)

Gets the number of cells on a given row.

3

FlexTable.FlexCellFormatter getFlexCellFormatter()

Explicitly gets the FlexTable.FlexCellFormatter.

4

int getRowCount()

Gets the number of rows.

5

void insertCell(int beforeRow, int beforeColumn)

Inserts a cell into the FlexTable.

6

int insertRow(int beforeRow)

Inserts a row into the FlexTable.

7

protected void prepareCell(int row, int column)

Ensure that the cell exists.

8

protected void prepareRow(int row)

Ensure that the row exists.

9

void removeAllRows()

Remove all rows in this table.

10

void removeCell(int row, int col)

Removes the specified cell from the table.

11

void removeCells(int row, int column, int num)

Removes a number of cells from a row in the table.

12

void removeRow(int row)

Removes the specified row from the table.

Methods Inherited

This class inherits methods from the following classes −

  • com.google.gwt.user.client.ui.UIObject

  • com.google.gwt.user.client.ui.Widget

  • com.google.gwt.user.client.ui.Panel

  • com.google.gwt.user.client.ui.HTMLTable

  • java.lang.Object

FlexTable Widget Example

This example will take you through simple steps to show usage of a FlexTable Widget in GWT. Follow the following steps to update the GWT application we created in GWT - Create Application chapter −

Step Description
1 Create a project with a name HelloWorld under a package com.tutorialspoint as explained in the GWT - Create Application chapter.
2 Modify HelloWorld.gwt.xml, HelloWorld.css, HelloWorld.html and HelloWorld.java as explained below. Keep rest of the files unchanged.
3 Compile and run the application to verify the result of the implemented logic.

Following is the content of the modified module descriptor src/com.tutorialspoint/HelloWorld.gwt.xml.

<?xml version = "1.0" encoding = "UTF-8"?>
<module rename-to = 'helloworld'>
   <!-- Inherit the core Web Toolkit stuff.                        -->
   <inherits name = 'com.google.gwt.user.User'/>

   <!-- Inherit the default GWT style sheet.                       -->
   <inherits name = 'com.google.gwt.user.theme.clean.Clean'/>

   <!-- Specify the app entry point class.                         -->
   <entry-point class = 'com.tutorialspoint.client.HelloWorld'/>

   <!-- Specify the paths for translatable code                    -->
   <source path = 'client'/>
   <source path = 'shared'/>

</module>

Following is the content of the modified Style Sheet file war/HelloWorld.css.

body {
   text-align: center;
   font-family: verdana, sans-serif;
}

h1 {
   font-size: 2em;
   font-weight: bold;
   color: #777777;
   margin: 40px 0px 70px;
   text-align: center;
}
.flexTable td {
   border: 1px solid #BBBBBB;
   padding: 3px;
}

.flexTable-buttonPanel td {
   border: 0px;
}

.fixedWidthButton {
   width: 150px;
}

Following is the content of the modified HTML host file war/HelloWorld.html.

<html>
   <head>
      <title>Hello World</title>
      <link rel = "stylesheet" href = "HelloWorld.css"/>
      <script language = "javascript" src = "helloworld/helloworld.nocache.js">
      </script>
   </head>

   <body>
      <h1>FlexTable Widget Demonstration</h1>
      <div id = "gwtContainer"></div>
   </body>
</html>

Let us have following content of Java file src/com.tutorialspoint/HelloWorld.java which will demonstrate use of FlexTable widget.

package com.tutorialspoint.client;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.DecoratorPanel;
import com.google.gwt.user.client.ui.FlexTable;
import com.google.gwt.user.client.ui.FlexTable.FlexCellFormatter;
import com.google.gwt.user.client.ui.HasHorizontalAlignment;
import com.google.gwt.user.client.ui.HasVerticalAlignment;
import com.google.gwt.user.client.ui.Image;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.VerticalPanel;

public class HelloWorld implements EntryPoint {

   public void onModuleLoad() {
      // Create a Flex Table
      final FlexTable flexTable = new FlexTable();
      FlexCellFormatter cellFormatter = flexTable.getFlexCellFormatter();
      flexTable.addStyleName("flexTable");
      flexTable.setWidth("32em");
      flexTable.setCellSpacing(5);
      flexTable.setCellPadding(3);

      // Add some text
      cellFormatter.setHorizontalAlignment(
      0, 1, HasHorizontalAlignment.ALIGN_LEFT);
      flexTable.setHTML(0, 0, "This is a FlexTable that supports"
         +" <b>colspans</b> and <b>rowspans</b>."
         +" You can use it to format your page"
         +" or as a special purpose table.");
      cellFormatter.setColSpan(0, 0, 2);

      // Add a button that will add more rows to the table
      Button addRowButton = new Button("Add a Row"); 
      addRowButton.addClickHandler(new ClickHandler() {
         @Override
         public void onClick(ClickEvent event) {
            addRow(flexTable);
         }
      });

      addRowButton.addStyleName("fixedWidthButton");

      // Add a button that will add more rows to the table
      Button removeRowButton = new Button("Remove a Row"); 
      removeRowButton.addClickHandler(new ClickHandler() {
         @Override
         public void onClick(ClickEvent event) {
            removeRow(flexTable);
         }
      });

      removeRowButton.addStyleName("fixedWidthButton");

      VerticalPanel buttonPanel = new VerticalPanel();
      buttonPanel.setStyleName("flexTable-buttonPanel");
      buttonPanel.add(addRowButton);
      buttonPanel.add(removeRowButton);
      flexTable.setWidget(0, 1, buttonPanel);
      cellFormatter.setVerticalAlignment(0, 1, 
      HasVerticalAlignment.ALIGN_TOP);

      // Add two rows to start
      addRow(flexTable);
      addRow(flexTable);

      // Add the widgets to the root panel.
      RootPanel.get().add(flexTable);
   }

   /**
    * Add a row to the flex table.
    */
   private void addRow(FlexTable flexTable) {
      int numRows = flexTable.getRowCount();
      flexTable.setWidget(numRows, 0, 
      new Image("http://www.tutorialspoint.com/images/gwt-mini.png"));
      flexTable.setWidget(numRows, 1, 
      new Image("http://www.tutorialspoint.com/images/gwt-mini.png"));
      flexTable.getFlexCellFormatter().setRowSpan(0, 1, numRows + 1);
   }

   /**
    * Remove a row from the flex table.
    */
   private void removeRow(FlexTable flexTable) {
      int numRows = flexTable.getRowCount();
      if (numRows > 1) {
         flexTable.removeRow(numRows - 1);
         flexTable.getFlexCellFormatter().setRowSpan(0, 1, numRows - 1);
      }
   }
}

Once you are ready with all the changes done, let us compile and run the application in development mode as we did in GWT - Create Application chapter. If everything is fine with your application, this will produce following result −

GWT FlexTable Widget
gwt_layout_panels.htm

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