Positioning GUI objects on a Frame

问题

I am developing a Java application and would like some help in positioning some Labels and TextFields.

Here is my code:

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JComboBox;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JTextField; 
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.FlowLayout;

public class AuctionClient
{
public AuctionClient()
{
    JFrame GUIFrame = new JFrame();
    JPanel GUIPanel = new JPanel();
    JLabel LabelUserName = new JLabel("UserName:");
    JTextField TextFieldUserName = new JTextField("                               ");

    JLabel LabelPassword = new JLabel("Password:");
    JTextField TextFieldPassword = new JTextField("                               ");        

    GUIFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    GUIFrame.setTitle("Auction Client");
    GUIFrame.setSize(500,250);

    GUIFrame.setLocationRelativeTo(null);

    GUIPanel.add(LabelUserName);
    GUIPanel.add(TextFieldUserName);        

    GUIPanel.add(LabelPassword);
    GUIPanel.add(TextFieldPassword);         

    GUIFrame.add(GUIPanel, BorderLayout.NORTH);
    GUIFrame.setVisible(true);
}  
}

With the above code, the LabelPassword and TextFieldPassword is on the same line as the LabelUsername and TextFieldUsername. Can I please have some help to position the LabelPassword and TextFieldPassword on a new line. Is it possible to specify X,Y coordinates to position objects on a JFrame?

Here is an image to show you how the objects are currently being shown:

http://canning.co.nz/Java/Positioning_Image.png

回答1:

You should never try to position components with coordinates. Rather use appropriate LayoutManager's and use logical conditions and constraints to position your components.

Here is one example using GridBagLayout:

import java.awt.BorderLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class AuctionClient {
    public AuctionClient() {
        JFrame guiFrame = new JFrame();
        JPanel guiPanel = new JPanel(new GridBagLayout());
        JLabel userNameLabel = new JLabel("UserName:");
        JTextField userNameTextField = new JTextField(30);

        JLabel passwordLabel = new JLabel("Password:");
        JTextField passwordTextField = new JPasswordField(30);

        guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        guiFrame.setTitle("Auction Client");
        guiFrame.setSize(500, 250);

        guiFrame.setLocationRelativeTo(null);
        GridBagConstraints labelGBC = new GridBagConstraints();
        labelGBC.insets = new Insets(3, 3, 3, 3);
        GridBagConstraints fieldGBC = new GridBagConstraints();
        fieldGBC.insets = new Insets(3, 3, 3, 3);
        fieldGBC.gridwidth = GridBagConstraints.REMAINDER;
        guiPanel.add(userNameLabel, labelGBC);
        guiPanel.add(userNameTextField, fieldGBC);

        guiPanel.add(passwordLabel, labelGBC);
        guiPanel.add(passwordTextField, fieldGBC);

        guiFrame.add(guiPanel, BorderLayout.NORTH);
        guiFrame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new AuctionClient();
            }
        });
    }
}

回答2:

GridLayout, SpringLayout, GridBagLayout can do that by default
easiest coud be GridLayout(2, 2, 10, 10),
1. but every JComponents are resizable with its container
2. have to change horizontal alingment for JLabel (setHorizontalAlignment(javax.swing.SwingConstants.RIGHT); or setHorizontalAlignment(JLabel.RIGHT);)
3. determine (JTextField TextFieldUserName = new JTextField(20)) initial Dimension for any of LayoutManager

来源：https://stackoverflow.com/questions/16397609/positioning-gui-objects-on-a-frame

标签

java

swing

jlabel

jtextfield