無法準確理解什麼以及如何使用GridBagConstraints。 As-Is vs. Should-Be

Question

我正在搞亂GridBagLayout。我已經有所瞭解，因此能夠做出這種佈局。但我的原來是不符合我的應該。這裏是屏幕。

AS-是:(

應該是：■

我明白，我必須調整它一下，讓大小設置（setSize()）但真正棘手。其中一個是讓「添加聯繫人」JLabel位於最上方的中心位置
正在等待您的回覆。

package SimpleCRUD; 

import java.awt.Component; 
import java.awt.Font; 
import java.awt.GridBagConstraints; 
import java.awt.GridBagLayout; 

import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JTextField; 

@SuppressWarnings("serial") 
public class ContactListFrame extends JFrame{ 
    JButton Button1, Button2; 
    JTextField textField1, textField2, textField3; 
    JLabel label1, label2, label3 , label4; 
    GridBagLayout layout = new GridBagLayout(); 
    GridBagConstraints Constraint = new GridBagConstraints(); 

    public ContactListFrame() { 
     super("All Contacts"); 
     Button1 = new JButton("Add"); 
     Button2 = new JButton("Cancel"); 
     textField1 = new JTextField(15); 
     textField2 = new JTextField(15); 
     textField3 = new JTextField(15); 
     label4 = new JLabel("Add Contact"); 
     label4.setFont (new Font("fallan", 1, 25)); 
     label1 = new JLabel("First Name:"); 
     label2 = new JLabel("Last Name:"); 
     label3 = new JLabel("Phone Number:"); 

     setLayout(layout); 
     setDefaultCloseOperation(DISPOSE_ON_CLOSE); 
     setSize(400, 200); 
     setResizable(false); 
     Constraint.fill = GridBagConstraints.NONE; 
     Constraint.anchor = GridBagConstraints.NORTH; 
     addComponent(label4, 0, 1, 1, 1); 
     addComponent(textField1, 1, 1, 1, 1); 
     addComponent(textField2, 2, 1, 1, 1); 
     addComponent(textField3, 3, 1, 1, 1); 
     addComponent(label1, 1, 0, 1, 1); 
     addComponent(label2, 2, 0, 1, 1); 
     addComponent(label3, 3, 0, 1, 1); 
     addComponent(Button1, 4, 0, 2, 1); 
     addComponent(Button2, 4, 1, 2, 1); 
    } 

    public void addComponent (Component comp, int row, int col, int width, int height){ 
     Constraint.gridx = col; 
     Constraint.gridy = row; 
     Constraint.gridwidth = width; 
     Constraint.gridheight = height; 
     layout.setConstraints(comp, Constraint); 
     add(comp); 
    } 

} 

Answer 1

如果你看一看的documentation of GridBagLayout，還有的GridBagConstraints使用的一個相當不錯的例子。

這裏是你的代碼修改爲使用的GridBagConstraints

import java.awt.Component; 
import java.awt.Font; 
import java.awt.GridBagConstraints; 
import java.awt.GridBagLayout; 

import java.awt.Insets; 

import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JTextField; 


public class ContactListFrame extends JFrame{ 
    JButton Button1, Button2; 
    JTextField textField1, textField2, textField3; 
    JLabel label1, label2, label3 , label4; 
    GridBagLayout layout = new GridBagLayout(); 
    GridBagConstraints Constraint = new GridBagConstraints(); 

    public ContactListFrame() { 
     super("All Contacts"); 
     Button1 = new JButton("Add"); 
     Button2 = new JButton("Cancel"); 
     textField1 = new JTextField(15); 
     textField2 = new JTextField(15); 
     textField3 = new JTextField(15); 
     label4 = new JLabel("Add Contact"); 
     label4.setFont (new Font("fallan", 1, 25)); 
     label1 = new JLabel("First Name:"); 
     label2 = new JLabel("Last Name:"); 
     label3 = new JLabel("Phone Number:"); 

     setLayout(layout); 
     setDefaultCloseOperation(EXIT_ON_CLOSE); 
     setSize(400, 200); 
     setResizable(false); 
     Constraint.fill = GridBagConstraints.BOTH; 
     Insets ins = new Insets(5, 5, 5, 5); 
     Constraint.insets = ins;//this does the padding 
     Constraint.weightx = 0.0; 
     Constraint.gridwidth = GridBagConstraints.REMAINDER;//end row 
     add(label4, Constraint); 
     Constraint.gridwidth = GridBagConstraints.RELATIVE;//next to last component 
     add(label1, Constraint); 
     Constraint.gridwidth = GridBagConstraints.REMAINDER;//end row 
     add(textField1, Constraint); 
     Constraint.gridwidth = GridBagConstraints.RELATIVE;//next to last component 
     add(label2, Constraint); 
     Constraint.gridwidth = GridBagConstraints.REMAINDER;//end row 
     add(textField2, Constraint); 
     Constraint.gridwidth = GridBagConstraints.RELATIVE;//next to last component 
     add(label3, Constraint); 
     Constraint.gridwidth = GridBagConstraints.REMAINDER;//end row 
     add(textField3, Constraint); 
     Constraint.gridwidth = GridBagConstraints.RELATIVE;//next to last component 
     add(Button1, Constraint); 
     Constraint.gridwidth = GridBagConstraints.REMAINDER;//end row 
     add(Button2, Constraint); 
    }   

    public static void main(String args[]) { 
     new ContactListFrame().setVisible(true); 
    } 
} 

輸出看起來像這樣