[英]Dr Java- Static Error: This class does not have a static void main method accepting String[]
I try running this program and I get a static void error.我尝试运行此程序,但出现静态无效错误。 I am new to this and I have no idea how to fix this problem so any input would be helpful, thank you!
我是新手,我不知道如何解决这个问题,所以任何输入都会有帮助,谢谢!
package johnbarthelmes.Java;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.ImageIcon;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Board extends JPanel implements ActionListener {
private final int B_WIDTH = 300;
private final int B_HEIGHT = 300;
private final int DOT_SIZE = 10;
private final int ALL_DOTS = 900;
private final int RAND_POS = 29;
private final int DELAY = 140;
private final int x[] = new int[ALL_DOTS];
private final int y[] = new int[ALL_DOTS];
private int dots;
private int apple_x;
private int apple_y;
private boolean leftDirection = false;
private boolean rightDirection = true;
private boolean upDirection = false;
private boolean downDirection = false;
private boolean inGame = true;
private Timer timer;
private Image ball;
private Image apple;
private Image head;
public Board() {
addKeyListener(new TAdapter());
setBackground(Color.black);
setFocusable(true);
setPreferredSize(new Dimension(B_WIDTH, B_HEIGHT));
loadImages();
initGame();
}
private void loadImages() {
ImageIcon iid = new ImageIcon("dot.png");
ball = iid.getImage();
ImageIcon iia = new ImageIcon("apple.png");
apple = iia.getImage();
ImageIcon iih = new ImageIcon("head.png");
head = iih.getImage();
}
private void initGame() {
dots = 3;
for (int z = 0; z < dots; z++) {
x[z] = 50 - z * 10;
y[z] = 50;
}
locateApple();
timer = new Timer(DELAY, this);
timer.start();
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
doDrawing(g);
}
private void doDrawing(Graphics g) {
if (inGame) {
g.drawImage(apple, apple_x, apple_y, this);
for (int z = 0; z < dots; z++) {
if (z == 0) {
g.drawImage(head, x[z], y[z], this);
} else {
g.drawImage(ball, x[z], y[z], this);
}
}
Toolkit.getDefaultToolkit().sync();
} else {
gameOver(g);
}
}
private void gameOver(Graphics g) {
String msg = "Game Over";
Font small = new Font("Helvetica", Font.BOLD, 14);
FontMetrics metr = getFontMetrics(small);
g.setColor(Color.white);
g.setFont(small);
g.drawString(msg, (B_WIDTH - metr.stringWidth(msg)) / 2, B_HEIGHT / 2);
}
private void checkApple() {
if ((x[0] == apple_x) && (y[0] == apple_y)) {
dots++;
locateApple();
}
}
private void move() {
for (int z = dots; z > 0; z--) {
x[z] = x[(z - 1)];
y[z] = y[(z - 1)];
}
if (leftDirection) {
x[0] -= DOT_SIZE;
}
if (rightDirection) {
x[0] += DOT_SIZE;
}
if (upDirection) {
y[0] -= DOT_SIZE;
}
if (downDirection) {
y[0] += DOT_SIZE;
}
}
private void checkCollision() {
for (int z = dots; z > 0; z--) {
if ((z > 4) && (x[0] == x[z]) && (y[0] == y[z])) {
inGame = false;
}
}
if (y[0] >= B_HEIGHT) {
inGame = false;
}
if (y[0] < 0) {
inGame = false;
}
if (x[0] >= B_WIDTH) {
inGame = false;
}
if (x[0] < 0) {
inGame = false;
}
if(!inGame) {
timer.stop();
}
}
private void locateApple() {
int r = (int) (Math.random() * RAND_POS);
apple_x = ((r * DOT_SIZE));
r = (int) (Math.random() * RAND_POS);
apple_y = ((r * DOT_SIZE));
}
@Override
public void actionPerformed(ActionEvent e) {
if (inGame) {
checkApple();
checkCollision();
move();
}
repaint();
}
private class TAdapter extends KeyAdapter {
@Override
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if ((key == KeyEvent.VK_LEFT) && (!rightDirection)) {
leftDirection = true;
upDirection = false;
downDirection = false;
}
if ((key == KeyEvent.VK_RIGHT) && (!leftDirection)) {
rightDirection = true;
upDirection = false;
downDirection = false;
}
if ((key == KeyEvent.VK_UP) && (!downDirection)) {
upDirection = true;
rightDirection = false;
leftDirection = false;
}
if ((key == KeyEvent.VK_DOWN) && (!upDirection)) {
downDirection = true;
rightDirection = false;
leftDirection = false;
}
}
}
}
If it helps at all this is the code for the snake game that I got from a Dr Java tutorial in which I followed all the steps correctly as far as I know.如果它有帮助的话,这是我从 Java 博士教程中获得的蛇游戏的代码,据我所知,我在其中正确地遵循了所有步骤。 There was no errors compiling but when I ran the program I got that error message.
编译没有错误,但是当我运行程序时,我收到了该错误消息。
In order to run an application, your class needs a main
method with a certain signature, so Java knows what to do.为了运行应用程序,您的类需要一个具有特定签名的
main
方法,因此 Java 知道该做什么。 Probably you want to start up the program by showing your JFrame
:可能您想通过显示
JFrame
来启动程序:
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
Board b = new Board();
b.setVisible(true);
}
});
}
You need to add a main method.您需要添加一个主要方法。 It's the entry point to every Java application.
它是每个 Java 应用程序的入口点。 It looks like it should have this implementation, based on your code sample.
根据您的代码示例,它看起来应该有这个实现。
public static void main(String[] args) {
Board board = new Board();
// need to do something else with board here maybe?
}
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