如何推动 GridbagLayout 不在 JPanel 的中心放置组件

Question

问题在于组件的居中布局，GridBagLayout 总是“位于”JPanel 的中心，所以我不在乎它如何在内部布局组件，我的问题是这些组件将开始在面板上布局的位置。

我试过了：

panel.setAlignmentX( JPanel.LEFT_ALIGNMENT );

但它没有帮助。

有什么想法吗？

Answer 1

您需要添加至少一个将填充水平空间的组件。如果你没有这样的组件，你可以试试这个：

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

除了设置anchor 和fill 字段外，您可能还需要设置weightx 字段。这有助于指定调整大小的行为。

Quote:

除非您为 weightx 或 weighty 指定至少一个非零值，否则所有组件都会在其容器的中心聚集在一起。这是因为当权重为 0.0（默认值）时，GridBagLayout 会在其单元格网格和容器边缘之间放置任何额外的空间。

以下将保持myComponent 锚定到NORTHWEST 角落。假设 this 是 JPanel 或类似的：

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);

要保持子组件左对齐但垂直居中，只需设置 anchor = WEST 并删除 weighty = 1;。

Answer 3

您只需使用此实用程序 jar painless-gridbag 即可完成。它还使您的 GridBagLayout 代码更漂亮，如下所示

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

如果您想更改组件在由GridBagLayout 创建的单元格中的位置，请使用GridBagConstraints 中的参数anchor。

Answer 5

我和你有同样的问题。通过将该面板添加到另一个具有 BorderLayout 和 NORTH 约束的面板来解决它。

翁德瑞

Answer 6

您可以将主布局设置为flowlayout，并将对齐设置为left。在这个面板（flowlayout）中，添加一个gridbaglayout面板。这也适用于netbeans

Answer 7

另一种解决方案是在最右侧、最底部添加两个虚拟面板（容器）。然后你调整 weightx 和 weighty 来分配额外的空间。如果将 1 设置为虚拟对象，则所有额外空间都分配给该虚拟对象。

这是在 netbeans 中形成的示例。

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                   
}