我想说这个问题很可能是重复的，但我不确定究竟是什么问题：由于这个原因，我无法进行正确的搜索。
我目前正在研究Java中的绘画程序。我正在尝试存储在Shape对象的ArrayList中绘制形状的指令。我也使用MouseListener来获取坐标。
目标是当按下鼠标时，它会记录该点。当它被释放时，它会保留第二个点的记录，然后将两个坐标发送到构造函数的行history.add（new Shape（x，y，x2，y2））。
相关代码如下：
// Create an ArrayList for the History
static ArrayList history = new ArrayList(0);
.
.
.
// Co-ordinates for rectangle painting
static int x = 0;
static int y = 0;
static int x2 = 0;
static int y2 = 0;
.
.
.
/**
* A class for handling mouse input
*
* All methods within the MouseHandler class MUST be there
* If not, the code will not compile.
*/
private static class MouseHandler implements MouseListener
{
public void mousePressed(MouseEvent e) {
x = e.getX();
y = e.getY();
}
public void mouseReleased(MouseEvent e) {
x2 = e.getX();
y2 = e.getY();
//repaint() is a special method that must be called to "repaint"
//your shapes on the screen.
canvas.repaint();
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void mouseClicked(MouseEvent e) {
// Create a new shape on the button unclick
history.add(new Shape(x, y, x2, y2));
}
}
此代码在行history.add（new Shape（x，y，x2，y2））中抛出异常; ：“非静态方法，这不能从静态上下文中引用。”该错误似乎特别引用（new Shape（x，y，x2，y2））。我不明白为什么这种方法是非静态的。
提前非常感谢任何帮助， Placowdepuss
编辑：这是我的完整代码：
//Import packages needed
// For the GUI
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
// For the ArrayList
import java.util.*;
/**
* A simple drawing application.
*
* @author (Massimo A. Lipari)
* @version (1.0.0)
*/
public class PaintProgram
{
// Create the frame and the panels for the GUI
static JFrame frame = new JFrame("PaintIt");
static JPanel panel = new JPanel();
static JPanel buttonPanel = new JPanel();
static MyPanel canvas = new MyPanel();
static JLabel sampleText = new JLabel("Label");
// Create an array for the buttons
static JButton[] buttonArray = new JButton[12];
// Create an ArrayList for the History
static ArrayList<Shape> history = new ArrayList<Shape>();
// Co-ordinates for rectangle painting
static int x, y, x2, y2;
// Create a variable for keeping track of the active tool
static String activeTool;
// Variables for holding the current colour and fill settings
static boolean currentFill;
static Color currentColour;
public static void main(String[] args)
{
// Set the frame size
frame.setSize(1920,1040);
// Create the mouse listeners
canvas.addMouseListener(new MouseHandler());
// Set the size for the canvas portion of the screen
canvas.setSize(1920, 880);
// Add panels to frame
// Set layout for panel
panel.setLayout(new BorderLayout());
createButtonPanel();
panel.add(buttonPanel, BorderLayout.NORTH);
panel.add(canvas, BorderLayout.CENTER);
frame.getContentPane().add(panel);
// Set frame to visible and allows it to exit on closing of the frame
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void createButtonPanel()
{
// Set the buttonPanel size, and creates a grid layout for it
buttonPanel.setSize(1920, 160);
buttonPanel.setLayout(new GridLayout(1, 12));
// Initialize the buttons
for (int i = 0; i < buttonArray.length; i++) {
buttonArray[i] = new JButton("Button " + (i + 1));
// Create and add a button handler
buttonArray[i].addActionListener(new ButtonHandler());
buttonArray[i].setIcon(new ImageIcon("icon" + i + ".png"));
buttonArray[i].setBackground(Color.WHITE);
buttonPanel.add(buttonArray[i]);
}
}
/**
* A class for handling button input (the tools)
*/
private static class ButtonHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == buttonArray[0]) {
buttonArray[0].setBackground(JColorChooser.showDialog(null, "Choose a Color", sampleText.getForeground()));
} else if (e.getSource() == buttonArray[1]) {
currentFill = true;
buttonArray[1].setBackground(Color.LIGHT_GRAY);
buttonArray[2].setBackground(null);
} else if (e.getSource() == buttonArray[2]) {
currentFill = false;
buttonArray[1].setBackground(null);
buttonArray[2].setBackground(Color.LIGHT_GRAY);
} else if (e.getSource() == buttonArray[3]) {
activeTool = "paint";
} else if (e.getSource() == buttonArray[4]) {
activeTool = "rectangle";
} else if (e.getSource() == buttonArray[5]) {
activeTool = "triangle";
} else if (e.getSource() == buttonArray[6]) {
activeTool = "circle";
} else if (e.getSource() == buttonArray[7]) {
activeTool = "line";
} else if (e.getSource() == buttonArray[8]) {
activeTool = "text";
} else if (e.getSource() == buttonArray[9]) {
} else if (e.getSource() == buttonArray[10]) {
} else if (e.getSource() == buttonArray[11]) {
}
}
}
/**
* A class for handling mouse input
*
* All methods within the MouseHandler class MUST be there
* If not, the code will not compile.
*/
private static class MouseHandler implements MouseListener
{
public void mousePressed(MouseEvent e) {
x = e.getX();
y = e.getY();
}
public void mouseReleased(MouseEvent e) {
x2 = e.getX();
y2 = e.getY();
//repaint() is a special method that must be called to "repaint"
//your shapes on the screen.
canvas.repaint();
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void mouseClicked(MouseEvent e) {
// Create a new shape on the button unclick
history.add(new Shape(x, y, x2, y2));
}
}
/**
* A class for painting the shapes
*/
private static class MyPanel extends JPanel
{
public MyPanel() {
setBorder(BorderFactory.createLineBorder(Color.black));
setBackground(Color.white);
}
public Dimension getPreferredSize() {
return new Dimension(600,600);
}
// ALL drawing of shapes must be done in the paintComponent method
public void paintComponent(Graphics g) {
super.paintComponent(g);
//Drawing a basic rectangle from top left corner to bottom right on canvas
if (x2 >= x && y2 >= y)
g.drawRect(x, y, x2 - x, y2 - y);
else if (x2 >= x && y2 <= y)
g.drawRect(x, y2, x2 - x, y - y2);
else if (x2 <= x && y2 >= y)
g.drawRect(x2, y, x - x2, y2 - y);
else if (x2 <= x && y2 <= y)
g.drawRect(x2, y2, x - x2, y - y2);
}
}
/**
* A class that creates a colour picker
*
* This code is the property of Oracle Systems Inc. It is copyrighted.
*/
static class ColorChooser_01 extends JFrame
{
public static void main(String[] args) {
new ColorChooser_01();
}
public ColorChooser_01() {
this.setSize(300, 100);
JPanel panel1 = new JPanel();
sampleText.setBackground(null);
panel1.add(sampleText);
this.add(panel1);
this.setVisible(true);
}
public class ButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e) {
Color c = JColorChooser.showDialog(null, "Choose a Color", sampleText.getForeground());
if (c != null){
sampleText.setForeground(c);
buttonArray[0].setBackground(c);
}
else{
sampleText.setForeground(Color.WHITE);
}
}
}
}
/**
* A class for creating objects of type Shape
*/
public class Shape
{
// Variable for storing the type of shape
String type;
// Initialize variables for storing points for shape creation
int xcoord;
int ycoord;
int xcoord2;
int ycoord2;
// Boolean variable to control whether the shape is filled or not -- defaults to false
boolean fill = false;
// Variable to hold the coulour
Color colour;
public Shape(int newX, int newY, int newX2, int newY2)
{
type = activeTool;
xcoord = newX;
ycoord = newY;
xcoord2 = newX2;
ycoord2 = newY2;
fill = currentFill;
colour = currentColour;
}
public String getType()
{
return type;
}
public int getX()
{
return xcoord;
}
public int getY()
{
return ycoord;
}
public int getX2()
{
return xcoord2;
}
public int getY2()
{
return ycoord2;
}
public boolean getFill()
{
return fill;
}
public Color getColour()
{
return colour;
}
}
}
答案 0 :(得分：0)
您需要将shape类移动到另一个文件，因为在同一个文件中不能有两个公共类