How to push GridbagLayout not to lay components in the center of JPanel

Question

the problem is in centered layout of components, GridBagLayout always 'sits' in center of JPanel, so I don't care how it will layout components inside, my problem is where these components will start laying out on a panel.

I tried with:

panel.setAlignmentX( JPanel.LEFT_ALIGNMENT );

but it did not helped.

Any idea?

Answer 1

You need to add at least one component that will fill the horizontal space. If you don't have such a component you can try this:

GridBagConstraints noFill = new GridBagConstraints();
noFill.anchor = GridBagConstraints.WEST;
noFill.fill = GridBagConstraints.NONE;

GridBagConstraints horizontalFill = new GridBagConstraints();
horizontalFill.anchor = GridBagConstraints.WEST;
horizontalFill.fill = GridBagConstraints.HORIZONTAL;    

panel.add(new JLabel("Left Aligned"), noFill);
panel.add(Box.createHorizontalGlue(), horizontalFill);

Answer 2

In addition to setting the anchor and fill fields, you will likely need to set the weightx field. This helps specify resizing behavior.

Quote :

Unless you specify at least one non-zero value for weightx or weighty, all the components clump together in the center of their container. This is because when the weight is 0.0 (the default), the GridBagLayout puts any extra space between its grid of cells and the edges of the container.

The following will keep myComponent anchored to the NORTHWEST corner. Assuming this is JPanel or similar:

setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();

// Specify horizontal fill, with top-left corner anchoring
c.fill = GridBagConstraints.HORIZONTAL;
c.anchor = GridBagConstraints.NORTHWEST;

// Select x- and y-direction weight. Without a non-zero weight,
// the component will still be centered in the given direction.
c.weightx = 1;
c.weighty = 1;

// Add child component
add(myComponent, c);

To keep child components left-aligned yet vertically-centered, just set anchor = WEST and remove weighty = 1; .

Answer 3

You can done it by simply use this utility jar painless-gridbag . It also make your code with GridBagLayout much prettier, like following

PainlessGridBag gbl = new PainlessGridBag(getContentPane(), false);

gbl.row().cell(lblFirstName).cell(txtFirstName).fillX()
        .cell(lblFamilyName).cell(txtFamilyName).fillX();
gbl.row().cell(lblAddress).cellXRemainder(txtAddress).fillX();

gbl.doneAndPushEverythingToTop();

Answer 4

如果要更改组件在GridBagLayout创建的单元格中的位置，请使用GridBagConstraints 中的参数锚点。

Answer 5

I had the same problem as you. Solved it by adding that Panel into another one with BorderLayout and NORTH constraint.

Ondrej

Answer 6

You can set main layout as flowlayout and set alignment as left. in this panel (flowlayout), add a panel which is gridbaglayout. also this is worked in netbeans

Answer 7

Another solution is that you add two dummy panel (container) to the most right, the most bottom. then you adjust weightx and weighty to distribute extra space. if you set 1 to the dummy then all extra space assign to this dummy.

this is an example forming in netbeans.

package tutorial;

/**
 *
 * @author ttn
 */
public class GridBag1 extends javax.swing.JPanel {

    /**
     * Creates new form GridBag1
     */
    public GridBag1() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {
        java.awt.GridBagConstraints gridBagConstraints;

        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jPanel1 = new javax.swing.JPanel();
        jPanel2 = new javax.swing.JPanel();
        jLabel2 = new javax.swing.JLabel();
        jTextField2 = new javax.swing.JTextField();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();

        setLayout(new java.awt.GridBagLayout());

        jLabel1.setText("jLabel1");
        gridBagConstraints = new java.awt.GridBagConstraints();
        gridBagConstraints.gridx = 0;
        gridBagConstraints.gridy = 0;
        add(jLabel1, gridBagConstraints);

        jTextField1.setText("jTextField1");
        jTextField1.setMinimumSize(new java.awt.Dimension(59, 20));
        gridBagConstraints = new java.awt.GridBagConstraints();
        gridBagConstraints.gridx = 1;
        gridBagConstraints.gridy = 0;
        gridBagConstraints.fill = java.awt.GridBagConstraints.HORIZONTAL;
        gridBagConstraints.weightx = 0.3;
        add(jTextField1, gridBagConstraints);

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 227, Short.MAX_VALUE)
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 104, Short.MAX_VALUE)
        );

        gridBagConstraints = new java.awt.GridBagConstraints();
        gridBagConstraints.gridx = 2;
        gridBagConstraints.gridy = 0;
        gridBagConstraints.gridheight = 3;
        gridBagConstraints.fill = java.awt.GridBagConstraints.BOTH;
        gridBagConstraints.weightx = 1.0;
        add(jPanel1, gridBagConstraints);

        javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
        jPanel2.setLayout(jPanel2Layout);
        jPanel2Layout.setHorizontalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 172, Short.MAX_VALUE)
        );
        jPanel2Layout.setVerticalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 196, Short.MAX_VALUE)
        );

        gridBagConstraints = new java.awt.GridBagConstraints();
        gridBagConstraints.gridx = 0;
        gridBagConstraints.gridy = 3;
        gridBagConstraints.gridwidth = 2;
        gridBagConstraints.fill = java.awt.GridBagConstraints.BOTH;
        gridBagConstraints.weighty = 1.0;
        add(jPanel2, gridBagConstraints);

        jLabel2.setText("jLabel2");
        gridBagConstraints = new java.awt.GridBagConstraints();
        gridBagConstraints.gridx = 0;
        gridBagConstraints.gridy = 1;
        add(jLabel2, gridBagConstraints);

        jTextField2.setText("jTextField2");
        jTextField2.setMinimumSize(new java.awt.Dimension(59, 20));
        gridBagConstraints = new java.awt.GridBagConstraints();
        gridBagConstraints.gridx = 1;
        gridBagConstraints.gridy = 1;
        gridBagConstraints.fill = java.awt.GridBagConstraints.HORIZONTAL;
        gridBagConstraints.weightx = 0.3;
        add(jTextField2, gridBagConstraints);

        jScrollPane1.setMinimumSize(new java.awt.Dimension(104, 64));

        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);

        gridBagConstraints = new java.awt.GridBagConstraints();
        gridBagConstraints.gridx = 0;
        gridBagConstraints.gridy = 2;
        gridBagConstraints.gridwidth = 2;
        gridBagConstraints.anchor = java.awt.GridBagConstraints.FIRST_LINE_START;
        add(jScrollPane1, gridBagConstraints);
    }// </editor-fold>                        


    // Variables declaration - do not modify                     
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    // End of variables declaration                   
}