当我尝试导出为Runnable JAR文件时，我没有“启动配置”的选项。为什么是这样？我是编程新手，有人可以帮助我吗？
这是Snake游戏的代码。我需要一个main（）？
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.net.URL;
import java.util.LinkedList;
import java.util.Random;
import javax.swing.JOptionPane;
@SuppressWarnings("serial")
public class snakeCanvas extends Canvas implements Runnable, KeyListener
{
private final int BOX_HEIGHT = 15;
private final int BOX_WIDTH = 15;
private final int GRID_HEIGHT = 25;
private final int GRID_WIDTH = 25;
private LinkedList<Point> snake;
private Point fruit;
private int direction = Direction.NO_DIRECTION;
private Thread runThread; //allows us to run in the background
private int score = 0;
private String highScore = "";
private Image menuImage = null;
private boolean isInMenu = true;
public void paint(Graphics g)
{
if (runThread == null)
{
this.setPreferredSize(new Dimension(640, 480));
this.addKeyListener(this);
runThread = new Thread(this);
runThread.start();
}
if (isInMenu)
{
DrawMenu(g);
//draw menu
}
else
{
if (snake == null)
{
snake = new LinkedList<Point>();
GenerateDefaultSnake();
PlaceFruit();
}
if (highScore.equals(""))
{
highScore = this.GetHighScore();
System.out.println(highScore);
}
DrawSnake(g);
DrawFruit(g);
DrawGrid(g);
DrawScore(g);
//draw everything else
}
}
public void DrawMenu(Graphics g)
{
if (this.menuImage == null)
{
try
{
URL imagePath = snakeCanvas.class.getResource("snakeMenu.png");
this.menuImage = Toolkit.getDefaultToolkit().getImage(imagePath);
}
catch (Exception e)
{
e.printStackTrace();
}
}
g.drawImage(menuImage, 0, 0, 640, 480, this);
}
public void update(Graphics g)
{
Graphics offScreenGraphics;
BufferedImage offscreen = null;
Dimension d= this.getSize();
offscreen = new BufferedImage(d.width, d.height, BufferedImage.TYPE_INT_ARGB);
offScreenGraphics = offscreen.getGraphics();
offScreenGraphics.setColor(this.getBackground());
offScreenGraphics.fillRect(0, 0, d.width, d.height);
offScreenGraphics.setColor(this.getForeground());
paint(offScreenGraphics);
g.drawImage(offscreen, 0, 0, this);
}
public void GenerateDefaultSnake()
{
score = 0;
snake.clear();
snake.add(new Point (0,2));
snake.add(new Point(0,1));
snake.add(new Point(0,0));
direction = Direction.NO_DIRECTION;
}
public void Move() //adds a new 'block' at front of snake, deleting the back 'block' to create movement
{
Point head = snake.peekFirst(); //grab the first item with no problems
Point newPoint = head;
switch (direction) {
case Direction.NORTH:
newPoint = new Point(head.x, head.y - 1); //vector of -j
break;
case Direction.SOUTH:
newPoint = new Point(head.x, head.y + 1);
break;
case Direction.WEST:
newPoint = new Point(head.x - 1, head.y);
break;
case Direction.EAST:
newPoint = new Point (head.x + 1, head.y);
break;
}
snake.remove(snake.peekLast()); //delete the last block
if (newPoint.equals(fruit))
{
//the snake hits the fruit
score+=10;
Point addPoint = (Point) newPoint.clone(); //creating the end piece upon eating fruit
switch (direction) {
case Direction.NORTH:
newPoint = new Point(head.x, head.y - 1); //vector of -j
break;
case Direction.SOUTH:
newPoint = new Point(head.x, head.y + 1);
break;
case Direction.WEST:
newPoint = new Point(head.x - 1, head.y);
break;
case Direction.EAST:
newPoint = new Point (head.x + 1, head.y);
break;
}
//the movement upon eating fruit
snake.push(addPoint);
PlaceFruit();
}
else if (newPoint.x < 0 || newPoint.x > (GRID_WIDTH - 1))
{
//snake has gone out of bounds - reset game
CheckScore();
GenerateDefaultSnake();
return;
}
else if (newPoint.y < 0 || newPoint.y > (GRID_HEIGHT - 1))
{
//snake has gone out of bounds - reset game
CheckScore();
GenerateDefaultSnake();
return;
}
else if (snake.contains(newPoint))
{
//running into your tail - reset game
CheckScore();
GenerateDefaultSnake();
return;
}
snake.push(newPoint);
}
public void DrawScore(Graphics g)
{
g.drawString("Score: " + score, 0, BOX_HEIGHT * GRID_HEIGHT + 15);
g.drawString("Highscore:" + highScore, 0, BOX_HEIGHT * GRID_HEIGHT + 30);
}
public void CheckScore()
{
if (highScore.equals(""))
return;
if (score > Integer.parseInt((highScore.split(":")[1])))
{
String name = JOptionPane.showInputDialog("New highscore. Enter your name!");
highScore = name + ":" + score;
File scoreFile = new File("highscore.dat");
if (!scoreFile.exists())
{
try {
scoreFile.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
FileWriter writeFile = null;
BufferedWriter writer = null;
try
{
writeFile = new FileWriter(scoreFile);
writer = new BufferedWriter(writeFile);
writer.write(this.highScore);
}
catch (Exception e)
{
}
finally
{
try
{
if (writer != null)
writer.close();
}
catch (Exception e) {}
}
}
}
public void DrawGrid(Graphics g)
{
//drawing the outside rectangle
g.drawRect(0, 0, GRID_WIDTH * BOX_WIDTH, GRID_HEIGHT * BOX_HEIGHT);
//drawing the vertical lines
for (int x = BOX_WIDTH; x < GRID_WIDTH * BOX_WIDTH; x+=BOX_WIDTH)
{
g.drawLine(x, 0, x, BOX_HEIGHT * GRID_HEIGHT);
}
//drawing the horizontal lines
for (int y = BOX_HEIGHT; y < GRID_HEIGHT * BOX_HEIGHT; y+=BOX_HEIGHT)
{
g.drawLine(0, y, GRID_WIDTH * BOX_WIDTH, y);
}
}
public void DrawSnake(Graphics g)
{
g.setColor(Color.ORANGE);
for (Point p : snake)
{
g.fillRect(p.x * BOX_WIDTH, p.y * BOX_HEIGHT, BOX_WIDTH, BOX_HEIGHT);
}
g.setColor(Color.BLACK);
}
public void DrawFruit(Graphics g)
{
g.setColor(Color.RED);
g.fillOval(fruit.x * BOX_WIDTH, fruit.y * BOX_HEIGHT, BOX_WIDTH, BOX_HEIGHT);
g.setColor(Color.BLACK);
}
public void PlaceFruit()
{
Random rand = new Random();
int randomX = rand.nextInt(GRID_WIDTH);
int randomY = rand.nextInt(GRID_HEIGHT);
Point randomPoint = new Point(randomX, randomY);
while (snake.contains(randomPoint)) //If the fruit happens to spawn on the snake, it will change position
{
randomX= rand.nextInt(GRID_WIDTH);
randomY= rand.nextInt(GRID_HEIGHT);
randomPoint = new Point(randomX, randomY);
}
fruit = randomPoint;
}
@Override
public void run() {
while (true)
{
repaint();
//runs indefinitely (CONSTANTLY LOOPS)
if (!isInMenu)
Move();
//Draws grid, snake and fruit
//buffer to slow down the snake
try
{
Thread.currentThread();
Thread.sleep(100);
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
public String GetHighScore()
{
FileReader readFile = null;
BufferedReader reader = null;
try
{
readFile = new FileReader("highscore.dat");
reader = new BufferedReader(readFile);
return reader.readLine();
}
catch (Exception e)
{
return "Nobody:0";
}
finally
{
try{
if (reader != null)
reader.close();
} catch (IOException e){
e.printStackTrace();
}
}
}
@Override
public void keyPressed(KeyEvent e) {
switch (e.getKeyCode())
{
case KeyEvent.VK_UP:
if (direction != Direction.SOUTH)
direction = Direction.NORTH;
break;
case KeyEvent.VK_DOWN:
if (direction != Direction.NORTH)
direction = Direction.SOUTH;
break;
case KeyEvent.VK_RIGHT:
if (direction != Direction.WEST)
direction = Direction.EAST;
break;
case KeyEvent.VK_LEFT:
if (direction != Direction.EAST)
direction = Direction.WEST;
break;
case KeyEvent.VK_ENTER:
if (isInMenu)
{
isInMenu = false;
repaint();
}
break;
case KeyEvent.VK_ESCAPE:
isInMenu = true;
break;
}
}
@Override
public void keyReleased(KeyEvent e) {
}
@Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
}
答案 0 :(得分：1)
基本上，您需要一个已用于执行Java应用程序的Run配置，以获得可运行的jar文件。这用于选择程序的正确起点。
如果使用“运行”命令（从“运行”菜单或工具栏）执行了Java应用程序，则会创建一个执行的运行配置。但是，根据您的问题判断，您还没有这样做，因为您没有为您的应用程序定义入口点。
因为java使用static main method with predefined parameters，所以可以执行具有这种方法的任何Java类。成功执行应用程序后，可以启动它，然后可以使用创建的运行配置导出jar文件。