问题
The code below produces nine individual JPanels in which are 9 buttons. The nine JPanels are arranged onto a base JPanel using GridLayout. This base JPanel is then placed onto the ContentPane using Border Layout. I'm using borders for the JButtons and each individual JPanel to clearly define their separation. The JButtons inside each JPanel look fine but there is a gap between the JPanels which is causing the appearance of a double line which is bugging the hell out of me. I've tried adding each individual JPanel onto the ContentPane directly but this does nothing. Totally stumped and wondering if anyone has any suggestions?
P.S. I know the mass of duplicate code needs re-factoring in a bad way and it will, this is just for mock-up purposes.
Thanks,
import java.awt.*;
import javax.swing.*;
import javax.swing.UIManager.*;
public class View1 extends JFrame
{
private JPanel basePanel;
private JPanel childPanel1;
private JPanel childPanel2;
private JPanel childPanel3;
private JPanel childPanel4;
private JPanel childPanel5;
private JPanel childPanel6;
private JPanel childPanel7;
private JPanel childPanel8;
private JPanel childPanel9;
private int row = 3;
private int column = 3;
private JButton[][] squares1;
private JButton[][] squares2;
private JButton[][] squares3;
private JButton[][] squares4;
private JButton[][] squares5;
private JButton[][] squares6;
private JButton[][] squares7;
private JButton[][] squares8;
private JButton[][] squares9;
private Font numberFont;
public View1()
{
setSize(400,400);
setTitle("2013");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
basePanel = new JPanel();
basePanel.setLayout(new GridLayout(row, column, 0, 0));
numberFont = new Font("sansserif", Font.BOLD, 32);
childPanel1Setup();
childPanel2Setup();
childPanel3Setup();
childPanel4Setup();
childPanel5Setup();
childPanel6Setup();
childPanel7Setup();
childPanel8Setup();
childPanel9Setup();
basePanel.add(childPanel1);
basePanel.add(childPanel2);
basePanel.add(childPanel3);
basePanel.add(childPanel4);
basePanel.add(childPanel5);
basePanel.add(childPanel6);
basePanel.add(childPanel7);
basePanel.add(childPanel8);
basePanel.add(childPanel9);
Container cp = getContentPane();
cp.setLayout(new BorderLayout());
cp.add(basePanel, BorderLayout.CENTER);
}
public void childPanel1Setup()
{
childPanel1 = new JPanel();
childPanel1.setLayout(new GridLayout(row, column, 0, 0));
childPanel1.setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares1 = new JButton[row][column];
for(int rows = 0; rows < this.row; rows++)
{
for(int cols = 0; cols < this.column; cols++)
{
squares1[rows][cols] = new JButton();
squares1[rows][cols].setSize(32, 32);
squares1[rows][cols].setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares1[rows][cols].setBackground(Color.WHITE);
childPanel1.add(squares1[rows][cols]);
}
}
}
public void childPanel2Setup()
{
childPanel2 = new JPanel();
childPanel2.setLayout(new GridLayout(row, column, 0, 0));
childPanel2.setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares2 = new JButton[row][column];
for(int rows = 0; rows < this.row; rows++)
{
for(int cols = 0; cols < this.column; cols++)
{
squares2[rows][cols] = new JButton();
squares2[rows][cols].setSize(32, 32);
squares2[rows][cols].setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares2[rows][cols].setBackground(Color.WHITE);
childPanel2.add(squares2[rows][cols]);
}
}
}
public void childPanel3Setup()
{
childPanel3 = new JPanel();
childPanel3.setLayout(new GridLayout(row, column, 0, 0));
childPanel3.setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares3 = new JButton[row][column];
for(int rows = 0; rows < this.row; rows++)
{
for(int cols = 0; cols < this.column; cols++)
{
squares3[rows][cols] = new JButton();
squares3[rows][cols].setSize(32, 32);
squares3[rows][cols].setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares3[rows][cols].setBackground(Color.WHITE);
childPanel3.add(squares3[rows][cols]);
}
}
}
public void childPanel4Setup()
{
childPanel4 = new JPanel();
childPanel4.setLayout(new GridLayout(row, column, 0, 0));
childPanel4.setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares4 = new JButton[row][column];
for(int rows = 0; rows < this.row; rows++)
{
for(int cols = 0; cols < this.column; cols++)
{
squares4[rows][cols] = new JButton();
squares4[rows][cols].setSize(32, 32);
squares4[rows][cols].setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares4[rows][cols].setBackground(Color.WHITE);
childPanel4.add(squares4[rows][cols]);
}
}
}
public void childPanel5Setup()
{
childPanel5 = new JPanel();
childPanel5.setLayout(new GridLayout(row, column, 0, 0));
childPanel5.setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares5 = new JButton[row][column];
for(int rows = 0; rows < this.row; rows++)
{
for(int cols = 0; cols < this.column; cols++)
{
squares5[rows][cols] = new JButton();
squares5[rows][cols].setSize(32, 32);
squares5[rows][cols].setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares5[rows][cols].setBackground(Color.WHITE);
childPanel5.add(squares5[rows][cols]);
}
}
}
public void childPanel6Setup()
{
childPanel6 = new JPanel();
childPanel6.setLayout(new GridLayout(row, column, 0, 0));
childPanel6.setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares6 = new JButton[row][column];
for(int rows = 0; rows < this.row; rows++)
{
for(int cols = 0; cols < this.column; cols++)
{
squares6[rows][cols] = new JButton();
squares6[rows][cols].setSize(32, 32);
squares6[rows][cols].setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares6[rows][cols].setBackground(Color.WHITE);
childPanel6.add(squares6[rows][cols]);
}
}
}
public void childPanel7Setup()
{
childPanel7 = new JPanel();
childPanel7.setLayout(new GridLayout(row, column, 0, 0));
childPanel7.setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares7 = new JButton[row][column];
for(int rows = 0; rows < this.row; rows++)
{
for(int cols = 0; cols < this.column; cols++)
{
squares7[rows][cols] = new JButton();
squares7[rows][cols].setSize(32, 32);
squares7[rows][cols].setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares7[rows][cols].setBackground(Color.WHITE);
childPanel7.add(squares7[rows][cols]);
}
}
}
public void childPanel8Setup()
{
childPanel8 = new JPanel();
childPanel8.setLayout(new GridLayout(row, column, 0, 0));
childPanel8.setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares8 = new JButton[row][column];
for(int rows = 0; rows < this.row; rows++)
{
for(int cols = 0; cols < this.column; cols++)
{
squares8[rows][cols] = new JButton();
squares8[rows][cols].setSize(32, 32);
squares8[rows][cols].setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares8[rows][cols].setBackground(Color.WHITE);
childPanel8.add(squares8[rows][cols]);
}
}
}
public void childPanel9Setup()
{
childPanel9 = new JPanel();
childPanel9.setLayout(new GridLayout(row, column, 0, 0));
childPanel9.setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares9 = new JButton[row][column];
for(int rows = 0; rows < this.row; rows++)
{
for(int cols = 0; cols < this.column; cols++)
{
squares9[rows][cols] = new JButton();
squares9[rows][cols].setSize(32, 32);
squares9[rows][cols].setBorder(BorderFactory.createLineBorder(Color.BLACK));
squares9[rows][cols].setBackground(Color.WHITE);
childPanel9.add(squares9[rows][cols]);
}
}
}
}
回答1:
I believe it's because the Layout Manager for JPanels is FlowLayout which includes a margin. When you create the panels, set their layout to GridLayout which will give you 0 margin.
Also have you done setVgap(0); and setHgap(0); for the GridLayout?
回答2:
GridLayout makes all component to be of the same size. If it needs to layout matrix of 3x3 components inside JPanel that it 100x100 pixels, each component will be 33x33 pixels and there will be on extra pixel at the right and at the bottom because 100 is not factor of 3. If JPanel is 101x101 pixels, there will be extra pixels at all four edges.
Consider using GridBagLayout or Box or some other layout that is smarter than GridLayout.
来源：https://stackoverflow.com/questions/14692697/gap-between-jpanels-in-gridlayout