JTable如何手动对齐、改变大小、添加滚动面板？
How to manually align, change size, and add scroll pane of JTable?
我正在 Netbeans 中创建一个 JTable，我遇到了三个关于结构的小问题。
- 我似乎无法将我的 table 对准我想要的方向（比如北、东、南或西），现在它在我的 JButton 上徘徊令人讨厌。
- 如果我更改变量，我为设置 JTable 的尺寸而编写的代码不会执行任何操作。
- 我编写的用于添加 JScrollPane 的代码在我 运行 时没有显示。
我知道如果你不能解决所有三个问题，但我想我会把它们全部放在一个而不是三个不同的问题中，所以任何解决问题的帮助都将不胜感激！
**另请注意，忽略 ActionListener 之后的所有内容。我最终将使代码读取文本文件并将该数据排序为 ArrayList。然后以某种方式进入 table 而不是我在此示例中如何手动设置它。
这是我的代码（问题区域在评论中以粗体大写字体标记）：
主要：
package libraryinventory;
import javax.swing.JFrame;
import java.io.*;
public class MainClass {
static String[] bookArray;
public static void main(String[] args) {
GUICommandFunctions guiDemo = new GUICommandFunctions();
//What to do when window closes
guiDemo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// size of window in pixels
guiDemo.setSize(1000, 720);
//make window visible
guiDemo.setVisible(true);
}
}
图形界面 Class:
package libraryinventory;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.io.*;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.Box;
import static javax.swing.Box.createHorizontalBox;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextArea;
import javax.swing.SwingConstants;
public class GUICommandFunctions extends JFrame {
private JButton ButtonOne;
private JTable jt;
public GUICommandFunctions() {
this.setTitle("Library Inventory"); //Name of window
JPanel panel = new JPanel();
this.add(panel, BorderLayout.CENTER); //Location of panel for JButton
ButtonOne = LibraryContentButton();
panel.add(ButtonOne); //adding panel to JFrame
String[] columns = {"Title", "Author/Language", "Publisher", "Page Count", "Version Number/Genre/Topic", "Part of a series/Illustrator"}; //columns of the JTable
String[][] data = {{"The Keto Cookbook", "Chronicle Books", "304", "English", "Keto Cooking", "null"}, //data under the columns
{"The Hitchhiker's Guide to the Galaxy", "Del Rey", "224", "Douglas Adams", "Fantasy", "Y"}
};
jt = new JTable(data, columns){ //Makes it so can't edit data inside table once ran
public boolean isCellEditable(int data, int columns) {
return false;
}
};
jt.setPreferredScrollableViewportSize(new Dimension(450, 63)); //Set size. **HERE IS PROBLEM #2**
jt.setFillsViewportHeight(true); //Set visible
jt.setVerticalAlignment(JTable.BOTTOM_ALIGNMENT); //**HERE IS PROBLEM #1**
JScrollPane jps = new JScrollPane(jt); //add scroll **HERE IS PROBLEM #3**
add(jps);
}
private JButton LibraryContentButton() { //
JButton content = new JButton("Click to view all content");
content.setFocusable(false);
content.setBackground(Color.DARK_GRAY);
content.setForeground(Color.WHITE);
content.setFont(new Font("Arial", Font.BOLD, 20));
content.setToolTipText("Shows content of the entire library in a neatly ordered JTable");
content.setMargin(new Insets(10, 10, 10, 10));
content.setPreferredSize(new Dimension(300, 75));
content.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(rootPane, "Eventually will make this button load up the JTable");
}
});
return content;
}
static {
int arrayCount;
FileReader fr = null;
try {
fr = new FileReader("C:\Users\Mark Case\Documents\NetBeansProjects\LibraryInventory\src\libraryinventory\library.txt"); //Reads in text file
} catch (FileNotFoundException ex) {
Logger.getLogger(GUICommandFunctions.class.getName()).log(Level.SEVERE, null, ex);
}
BufferedReader reader = new BufferedReader(fr);
ArrayList<String> str = new ArrayList<>();
String line = "";
arrayCount = 0;
try {
while((line=reader.readLine())!=null) {
str.add(line);
arrayCount = arrayCount + 1;
}
} catch (IOException ex) {
Logger.getLogger(GUICommandFunctions.class.getName()).log(Level.SEVERE, null, ex);
}
// Here we would actually set the type to what the user wants (note: Set it to a "0" if the user wants all Books)
String selType = "2";
// Call method to select Books by category type
String methodResult = SelectType(str, arrayCount, selType);
}
private static String SelectType (ArrayList<String> str, int arrayCount, String selType) {
for (int i = 1; i < arrayCount; i++) {
String buffer = str.get(i);
String bookCat = buffer.substring(0,1);
// Print books by Category - "0" type means print all Books
if (selType.equals(bookCat)) {
System.out.println(buffer);
}
else if (selType.equals("0")) {
System.out.println(buffer);
}
}
return "0";
}
}
那么，让我们快速浏览一下构造函数...
public GUICommandFunctions() {
//...
JPanel panel = new JPanel();
this.add(panel, BorderLayout.CENTER); //Location of panel for JButton
ButtonOne = LibraryContentButton();
panel.add(ButtonOne); //adding panel to JFrame
//...
jt.setPreferredScrollableViewportSize(new Dimension(450, 63)); //Set size. **HERE IS PROBLEM #2**
jt.setFillsViewportHeight(true); //Set visible
jt.setVerticalAlignment(JTable.BOTTOM_ALIGNMENT); //**HERE IS PROBLEM #1**
JScrollPane jps = new JScrollPane(jt); //add scroll **HERE IS PROBLEM #3**
add(jps);
}
您将 panel 添加到 CENTER。由于您直接从 JFrame 扩展，布局已经 BorderLayout，所以这很好。
但随后您使用 add(jps); 添加 jps，这会将组件添加到布局默认位置，在 BorderLayout 的情况下是 CENTER。这是有问题的，因为 BorderLayout 只允许在每个位置管理一个组件，这解释了为什么 setPreferredScrollableViewportSize 不工作，因为 BorderLayout 忽略了它，并且使组件填充 CENTER
中可用的 space
所以，我修改了你的代码。首先，我从 JPanel 扩展而不是 JFrame。通常不鼓励直接从 JFrame 扩展，您不会向 class 添加任何新功能，将自己锁定在一个用例中，这通常只会让您生活更加困难。
其次，我把JScrollPane放在了BorderLayout
的SOUTH位置
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new GUICommandFunctionsPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class GUICommandFunctionsPane extends JPanel {
private JButton ButtonOne;
private JTable jt;
public GUICommandFunctionsPane() {
setLayout(new BorderLayout());
JPanel panel = new JPanel();
this.add(panel, BorderLayout.CENTER); //Location of panel for JButton
ButtonOne = LibraryContentButton();
panel.add(ButtonOne); //adding panel to JFrame
String[] columns = {"Title", "Author/Language", "Publisher", "Page Count", "Version Number/Genre/Topic", "Part of a series/Illustrator"}; //columns of the JTable
String[][] data = {{"The Keto Cookbook", "Chronicle Books", "304", "English", "Keto Cooking", "null"}, //data under the columns
{"The Hitchhiker's Guide to the Galaxy", "Del Rey", "224", "Douglas Adams", "Fantasy", "Y"}
};
jt = new JTable(data, columns) { //Makes it so can't edit data inside table once ran
public boolean isCellEditable(int data, int columns) {
return false;
}
};
jt.setPreferredScrollableViewportSize(new Dimension(450, 63)); //Set size. **HERE IS PROBLEM #2**
jt.setFillsViewportHeight(true); //Set visible
JScrollPane jps = new JScrollPane(jt);
add(jps, BorderLayout.SOUTH);
}
private JButton LibraryContentButton() { //
JButton content = new JButton("Click to view all content");
content.setFocusable(false);
content.setBackground(Color.DARK_GRAY);
content.setForeground(Color.WHITE);
content.setFont(new Font("Arial", Font.BOLD, 20));
content.setToolTipText("Shows content of the entire library in a neatly ordered JTable");
content.setMargin(new Insets(10, 10, 10, 10));
content.setPreferredSize(new Dimension(300, 75));
content.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(GUICommandFunctionsPane.this, "Eventually will make this button load up the JTable");
}
});
return content;
}
// static {
//
// int arrayCount;
//
// FileReader fr = null;
//
// try {
// fr = new FileReader("C:\Users\Mark Case\Documents\NetBeansProjects\LibraryInventory\src\libraryinventory\library.txt"); //Reads in text file
// } catch (FileNotFoundException ex) {
// Logger.getLogger(GUICommandFunctionsPane.class.getName()).log(Level.SEVERE, null, ex);
// }
//
// BufferedReader reader = new BufferedReader(fr);
// ArrayList<String> str = new ArrayList<>();
// String line = "";
// arrayCount = 0;
// try {
// while ((line = reader.readLine()) != null) {
// str.add(line);
// arrayCount = arrayCount + 1;
//
// }
// } catch (IOException ex) {
// Logger.getLogger(GUICommandFunctionsPane.class.getName()).log(Level.SEVERE, null, ex);
// }
//
// // Here we would actually set the type to what the user wants (note: Set it to a "0" if the user wants all Books)
// String selType = "2";
//
// // Call method to select Books by category type
// String methodResult = SelectType(str, arrayCount, selType);
//
// }
//
// private static String SelectType(ArrayList<String> str, int arrayCount, String selType) {
// for (int i = 1; i < arrayCount; i++) {
//
// String buffer = str.get(i);
// String bookCat = buffer.substring(0, 1);
//
// // Print books by Category - "0" type means print all Books
// if (selType.equals(bookCat)) {
// System.out.println(buffer);
// } else if (selType.equals("0")) {
// System.out.println(buffer);
// }
// }
// return "0";
// }
}
}
哦，我不鼓励你以这种方式使用 static 初始化程序，相反，这要么需要进入构造函数，要么你应该使用某种形式的依赖注入将信息传递给class
我正在 Netbeans 中创建一个 JTable，我遇到了三个关于结构的小问题。
- 我似乎无法将我的 table 对准我想要的方向（比如北、东、南或西），现在它在我的 JButton 上徘徊令人讨厌。
- 如果我更改变量，我为设置 JTable 的尺寸而编写的代码不会执行任何操作。
- 我编写的用于添加 JScrollPane 的代码在我 运行 时没有显示。
我知道如果你不能解决所有三个问题，但我想我会把它们全部放在一个而不是三个不同的问题中，所以任何解决问题的帮助都将不胜感激！
**另请注意，忽略 ActionListener 之后的所有内容。我最终将使代码读取文本文件并将该数据排序为 ArrayList。然后以某种方式进入 table 而不是我在此示例中如何手动设置它。
这是我的代码（问题区域在评论中以粗体大写字体标记）：
主要：
package libraryinventory;
import javax.swing.JFrame;
import java.io.*;
public class MainClass {
static String[] bookArray;
public static void main(String[] args) {
GUICommandFunctions guiDemo = new GUICommandFunctions();
//What to do when window closes
guiDemo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// size of window in pixels
guiDemo.setSize(1000, 720);
//make window visible
guiDemo.setVisible(true);
}
}
图形界面 Class:
package libraryinventory;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.io.*;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.Box;
import static javax.swing.Box.createHorizontalBox;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextArea;
import javax.swing.SwingConstants;
public class GUICommandFunctions extends JFrame {
private JButton ButtonOne;
private JTable jt;
public GUICommandFunctions() {
this.setTitle("Library Inventory"); //Name of window
JPanel panel = new JPanel();
this.add(panel, BorderLayout.CENTER); //Location of panel for JButton
ButtonOne = LibraryContentButton();
panel.add(ButtonOne); //adding panel to JFrame
String[] columns = {"Title", "Author/Language", "Publisher", "Page Count", "Version Number/Genre/Topic", "Part of a series/Illustrator"}; //columns of the JTable
String[][] data = {{"The Keto Cookbook", "Chronicle Books", "304", "English", "Keto Cooking", "null"}, //data under the columns
{"The Hitchhiker's Guide to the Galaxy", "Del Rey", "224", "Douglas Adams", "Fantasy", "Y"}
};
jt = new JTable(data, columns){ //Makes it so can't edit data inside table once ran
public boolean isCellEditable(int data, int columns) {
return false;
}
};
jt.setPreferredScrollableViewportSize(new Dimension(450, 63)); //Set size. **HERE IS PROBLEM #2**
jt.setFillsViewportHeight(true); //Set visible
jt.setVerticalAlignment(JTable.BOTTOM_ALIGNMENT); //**HERE IS PROBLEM #1**
JScrollPane jps = new JScrollPane(jt); //add scroll **HERE IS PROBLEM #3**
add(jps);
}
private JButton LibraryContentButton() { //
JButton content = new JButton("Click to view all content");
content.setFocusable(false);
content.setBackground(Color.DARK_GRAY);
content.setForeground(Color.WHITE);
content.setFont(new Font("Arial", Font.BOLD, 20));
content.setToolTipText("Shows content of the entire library in a neatly ordered JTable");
content.setMargin(new Insets(10, 10, 10, 10));
content.setPreferredSize(new Dimension(300, 75));
content.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(rootPane, "Eventually will make this button load up the JTable");
}
});
return content;
}
static {
int arrayCount;
FileReader fr = null;
try {
fr = new FileReader("C:\Users\Mark Case\Documents\NetBeansProjects\LibraryInventory\src\libraryinventory\library.txt"); //Reads in text file
} catch (FileNotFoundException ex) {
Logger.getLogger(GUICommandFunctions.class.getName()).log(Level.SEVERE, null, ex);
}
BufferedReader reader = new BufferedReader(fr);
ArrayList<String> str = new ArrayList<>();
String line = "";
arrayCount = 0;
try {
while((line=reader.readLine())!=null) {
str.add(line);
arrayCount = arrayCount + 1;
}
} catch (IOException ex) {
Logger.getLogger(GUICommandFunctions.class.getName()).log(Level.SEVERE, null, ex);
}
// Here we would actually set the type to what the user wants (note: Set it to a "0" if the user wants all Books)
String selType = "2";
// Call method to select Books by category type
String methodResult = SelectType(str, arrayCount, selType);
}
private static String SelectType (ArrayList<String> str, int arrayCount, String selType) {
for (int i = 1; i < arrayCount; i++) {
String buffer = str.get(i);
String bookCat = buffer.substring(0,1);
// Print books by Category - "0" type means print all Books
if (selType.equals(bookCat)) {
System.out.println(buffer);
}
else if (selType.equals("0")) {
System.out.println(buffer);
}
}
return "0";
}
}
那么，让我们快速浏览一下构造函数...
public GUICommandFunctions() {
//...
JPanel panel = new JPanel();
this.add(panel, BorderLayout.CENTER); //Location of panel for JButton
ButtonOne = LibraryContentButton();
panel.add(ButtonOne); //adding panel to JFrame
//...
jt.setPreferredScrollableViewportSize(new Dimension(450, 63)); //Set size. **HERE IS PROBLEM #2**
jt.setFillsViewportHeight(true); //Set visible
jt.setVerticalAlignment(JTable.BOTTOM_ALIGNMENT); //**HERE IS PROBLEM #1**
JScrollPane jps = new JScrollPane(jt); //add scroll **HERE IS PROBLEM #3**
add(jps);
}
您将 panel 添加到 CENTER。由于您直接从 JFrame 扩展，布局已经 BorderLayout，所以这很好。
但随后您使用 add(jps); 添加 jps，这会将组件添加到布局默认位置，在 BorderLayout 的情况下是 CENTER。这是有问题的，因为 BorderLayout 只允许在每个位置管理一个组件，这解释了为什么 setPreferredScrollableViewportSize 不工作，因为 BorderLayout 忽略了它，并且使组件填充 CENTER
所以，我修改了你的代码。首先，我从 JPanel 扩展而不是 JFrame。通常不鼓励直接从 JFrame 扩展，您不会向 class 添加任何新功能，将自己锁定在一个用例中，这通常只会让您生活更加困难。
其次，我把JScrollPane放在了BorderLayout
SOUTH位置
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new GUICommandFunctionsPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class GUICommandFunctionsPane extends JPanel {
private JButton ButtonOne;
private JTable jt;
public GUICommandFunctionsPane() {
setLayout(new BorderLayout());
JPanel panel = new JPanel();
this.add(panel, BorderLayout.CENTER); //Location of panel for JButton
ButtonOne = LibraryContentButton();
panel.add(ButtonOne); //adding panel to JFrame
String[] columns = {"Title", "Author/Language", "Publisher", "Page Count", "Version Number/Genre/Topic", "Part of a series/Illustrator"}; //columns of the JTable
String[][] data = {{"The Keto Cookbook", "Chronicle Books", "304", "English", "Keto Cooking", "null"}, //data under the columns
{"The Hitchhiker's Guide to the Galaxy", "Del Rey", "224", "Douglas Adams", "Fantasy", "Y"}
};
jt = new JTable(data, columns) { //Makes it so can't edit data inside table once ran
public boolean isCellEditable(int data, int columns) {
return false;
}
};
jt.setPreferredScrollableViewportSize(new Dimension(450, 63)); //Set size. **HERE IS PROBLEM #2**
jt.setFillsViewportHeight(true); //Set visible
JScrollPane jps = new JScrollPane(jt);
add(jps, BorderLayout.SOUTH);
}
private JButton LibraryContentButton() { //
JButton content = new JButton("Click to view all content");
content.setFocusable(false);
content.setBackground(Color.DARK_GRAY);
content.setForeground(Color.WHITE);
content.setFont(new Font("Arial", Font.BOLD, 20));
content.setToolTipText("Shows content of the entire library in a neatly ordered JTable");
content.setMargin(new Insets(10, 10, 10, 10));
content.setPreferredSize(new Dimension(300, 75));
content.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(GUICommandFunctionsPane.this, "Eventually will make this button load up the JTable");
}
});
return content;
}
// static {
//
// int arrayCount;
//
// FileReader fr = null;
//
// try {
// fr = new FileReader("C:\Users\Mark Case\Documents\NetBeansProjects\LibraryInventory\src\libraryinventory\library.txt"); //Reads in text file
// } catch (FileNotFoundException ex) {
// Logger.getLogger(GUICommandFunctionsPane.class.getName()).log(Level.SEVERE, null, ex);
// }
//
// BufferedReader reader = new BufferedReader(fr);
// ArrayList<String> str = new ArrayList<>();
// String line = "";
// arrayCount = 0;
// try {
// while ((line = reader.readLine()) != null) {
// str.add(line);
// arrayCount = arrayCount + 1;
//
// }
// } catch (IOException ex) {
// Logger.getLogger(GUICommandFunctionsPane.class.getName()).log(Level.SEVERE, null, ex);
// }
//
// // Here we would actually set the type to what the user wants (note: Set it to a "0" if the user wants all Books)
// String selType = "2";
//
// // Call method to select Books by category type
// String methodResult = SelectType(str, arrayCount, selType);
//
// }
//
// private static String SelectType(ArrayList<String> str, int arrayCount, String selType) {
// for (int i = 1; i < arrayCount; i++) {
//
// String buffer = str.get(i);
// String bookCat = buffer.substring(0, 1);
//
// // Print books by Category - "0" type means print all Books
// if (selType.equals(bookCat)) {
// System.out.println(buffer);
// } else if (selType.equals("0")) {
// System.out.println(buffer);
// }
// }
// return "0";
// }
}
}
哦，我不鼓励你以这种方式使用 static 初始化程序，相反，这要么需要进入构造函数，要么你应该使用某种形式的依赖注入将信息传递给class