问题
I am working on a typing app which includes the a keyboard but I have found a bit hard to re-size the space button to make it wider than the other buttons.. This is the way I am displaying and organizing my layout..
I can resize the whole buttons but its NOT what I want.. the whole point is to be resize just the space bar.. :)
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.Arrays;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class example extends JFrame
{
//Individual keyboard rows
String firstRow[] = {"~","1","2","3","4","5","6","7","8","9","0","-","+","BackSpace"};
String secondRow[] = {"Tab","Q","W","E","R","T","Y","U","I","O","P","[","]","\\"};
String thirdRow[] = {"Caps","A","S","D","F","G","H","J","K","L",":","\"","Enter"};
String fourthRow[] = {"Shift","Z","X","C","V","B","N","M",",",".","?"," ^" };
String fifthRow[]={" " ,"<" ,"v",">" };
String strText = "";
//all keys without shift key press
String noShift="`1234567890-=qwertyuiop[]\\asdfghjkl;'zxcvbnm,./";
//special characters on keyboard that has to be addressed during key press
String specialChars ="~-+[]\\;',.?";
//Jbuttons corresponding to each individual rows
JButton first[];
JButton second[];
JButton third[];
JButton fourth[];
JButton fifth[];
//Driver main method to start the application
public static void main(String[] args) {
//launch typing tutor
new example().setVisible(true);
}
// No argument constructor to create frame
public example()
{
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//set size of the content pane ie frame
this.getContentPane().setPreferredSize(new Dimension(1200,275));
initWidgets();
}
// Method to initialize frame component
private void initWidgets()
{
//set the layout and place component in place and pack it
setLayout(new BorderLayout());
//Various panel for the layout
JPanel jpNorth = new JPanel();
JPanel jpCenter = new JPanel();
JPanel jpKeyboard = new JPanel();
JPanel jpNote = new JPanel();
add( jpNorth, BorderLayout.NORTH);
add( jpNote);
add( jpCenter, BorderLayout.CENTER);
add(jpKeyboard, BorderLayout.SOUTH);
//layout for keyboard
jpKeyboard.setLayout(new GridLayout(5,1));
//pack the components
pack();
//paint first keyboard row and add it to the keyboard
first = new JButton[firstRow.length];
//get the panel for the row
JPanel p = new JPanel(new GridLayout(1, firstRow.length));
for(int i = 0; i < firstRow.length; ++i)
{
JButton b= new JButton(firstRow[i]);
b.setPreferredSize(new Dimension(100,50));
first[i] = b;
p.add(first[i]);
}
jpKeyboard.add(p);
//paint second keyboard row and add it to the keyboard
second = new JButton[secondRow.length];
//get the panel for the row
p = new JPanel(new GridLayout(1, secondRow.length));
for(int i = 0; i < secondRow.length; ++i)
{
second[i] = new JButton(secondRow[i]);
p.add(second[i]);
}
jpKeyboard.add(p);
//paint third keyboard row and add it to the keyboard
third = new JButton[thirdRow.length];
//get the panel for the row
p = new JPanel(new GridLayout(1, thirdRow.length));
for(int i = 0; i < thirdRow.length; ++i)
{
third[i] = new JButton(thirdRow[i]);
p.add(third[i]);
}
jpKeyboard.add(p);
//paint fourth keyboard row and add it to the keyboard
fourth = new JButton[fourthRow.length];
//get the panel for the row
p = new JPanel(new GridLayout(1, fourthRow.length));
for(int i = 0; i < fourthRow.length; ++i)
{
fourth[i] = new JButton(fourthRow[i]);
p.add(fourth[i]);
if(i==fourthRow.length-2)
p.add(new JPanel());
}
p.add(new JPanel());
jpKeyboard.add(p);
//paint the fifth row
fifth = new JButton[fifthRow.length];
//get the panel for the row
p = new JPanel(new GridLayout(1, fifthRow.length));
//put empty panel for layout adjustments
for(int i = 0; i < 1; ++i)
{
JPanel spacePanel = new JPanel();
p.add(spacePanel);
}
//draw the buttons
for(int i = 0; i < fifthRow.length; ++i)
{
if(i==1) //space bar panel
{
JButton b = new JButton(fifthRow[i]);
b.setPreferredSize(new Dimension(400,10));
b.setBounds(10, 10, 600, 100);
fifth[i]=b;
//add empty panels for layout
p.add(new JPanel());p.add(new JPanel());p.add(new JPanel());p.add(new JPanel());p.add(new JPanel());p.add(new JPanel());p.add(new JPanel());p.add(new JPanel());
}
else
{
fifth[i]=new JButton(fifthRow[i]);
}
if(i==0) //first black panel
{
//place a black panel at first
JPanel spacePanel = new JPanel();
p.add(spacePanel);
}
p.add(fifth[i]);
}
jpKeyboard.add(p);
} //end of initWidgets
}//end of class
Well, if any of you guys can walk me through I will really appreciate it and if you guys need any clarification or more info please just let me know.. :)
回答1:
What pack() does is pack the frame, using the preferred sizes of the components. What you are doing is pack()ing before add the components and setting their preferred sizes, so the pack() is insignificant to the components added after the call (in terms of preferred size. So pack() the frame after you add all the components and set their preferred sizes.
Another thing you need to consider is that GridLayout will not respect the preferred size of the components. It will actually make them all the same size.
See here to see which layout managers will respect preferred sizes. And restructure your code accordingly. I'd look into a GridBagLayout as MadProgrammer suggest, that way you can just use one layout manager. It's a little tricky if you have no experience with it. Another option is just to stick with the default FlowLayout of the JPanel and nest panels as you have done.
Also see Laying out Components Within a Container to learn about the layout mangers available and hot they work.
回答2:
There are two problems, one, you're calling pack before you've actually finished building the content. pack uses the contents preferred size to calculate the size of the window, this would cause you issues as the (potential) size of the content would be different to what you wanted. The fact it works is down to the use of setPreferredSize you called earlier, which you should avoid doing.
The second issue is the choice of layout manager. GridLayout will give each component within the container an equal amount of space, horizontally and vertically based on the avaiable space of the parent container.
A better solution might be to use GridBagLayout, for example.
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Example extends JFrame {
//Individual keyboard rows
String firstRow[] = {"~", "1", "2", "3", "4", "5", "6", "7", "8", "9", "0", "-", "+", "fill", "BackSpace"};
String secondRow[] = {"Tab", "Q", "W", "E", "R", "T", "Y", "U", "I", "O", "P", "[", "]", "\\"};
String thirdRow[] = {"Caps", "A", "S", "D", "F", "G", "H", "J", "K", "L", ":", "\"", "fill", "fill", "Enter"};
String fourthRow[] = {"Shift", "Z", "X", "C", "V", "B", "N", "M", ",", ".", "?", "blank", "^"};
String fifthRow[] = {"blank", "blank", "fill", "fill", "fill", "fill", "fill", "fill", "fill", "fill", "", "<", "v", ">"};
//Jbuttons corresponding to each individual rows
JButton first[];
JButton second[];
JButton third[];
JButton fourth[];
JButton fifth[];
//Driver main method to start the application
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
new Example().setVisible(true);
}
});
}
// No argument constructor to create frame
public Example() {
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
initWidgets();
}
// Method to initialize frame component
private void initWidgets() {
//set the layout and place component in place and pack it
setLayout(new BorderLayout());
//Various panel for the layout
JPanel jpNorth = new JPanel();
JPanel jpCenter = new JPanel();
JPanel jpKeyboard = new JPanel(new GridBagLayout());
JPanel jpNote = new JPanel();
add(jpNorth, BorderLayout.NORTH);
add(jpNote);
add(jpCenter, BorderLayout.CENTER);
add(jpKeyboard, BorderLayout.SOUTH);
first = new JButton[firstRow.length];
second = new JButton[secondRow.length];
third = new JButton[thirdRow.length];
fourth = new JButton[fourthRow.length];
fifth = new JButton[fifthRow.length];
addKeys(jpKeyboard, 0, firstRow, first);
addKeys(jpKeyboard, 1, secondRow, second);
addKeys(jpKeyboard, 2, thirdRow, third);
addKeys(jpKeyboard, 3, fourthRow, fourth);
addKeys(jpKeyboard, 4, fifthRow, fifth);
pack();
} //end of initWidgets
protected void addKeys(JPanel parent, int row, String[] keys, JButton[] buttons) {
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridy = row;
gbc.gridx = 0;
gbc.fill = GridBagConstraints.BOTH;
int gap = 0;
for (int index = 0; index < keys.length; index++) {
String key = keys[index];
if ("blank".equalsIgnoreCase(key)) {
gbc.gridx++;
} else if ("fill".equalsIgnoreCase(key)) {
gbc.gridwidth++;
gap++;
} else {
System.out.println("Add " + key);
JButton btn = new JButton(key);
buttons[index] = btn;
parent.add(btn, gbc);
gbc.gridx += gap + 1;
gbc.gridwidth = 1;
gap = 0;
}
}
}
}//end of class
If you find the answer useful, I would appreciate if you could mark @peeskillet's answer as correct, as he answered first and spotted a few problems I didn't...an upvote would be nice though ;)
来源：https://stackoverflow.com/questions/22394845/space-button-size-on-my-layout-keyboard-wont-resize