java - 如何使用 swing 组件向 JLabel 添加刷新计时器
问题描述
我正在创建一个迷宫游戏,并希望在 gameStage 上显示一个计时器。我试过使用 java.util 但它需要我摆脱我的摇摆计时器。我怎么能在游戏中添加一个刷新计时器
此代码用于制作包含按钮窗格和游戏阶段的游戏框架。
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.HashSet;
import java.util.Set;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
/**
* This class Holds the game pane that has the moving player. It also contains
* the GamePane
*
* @author 602052004
*
*/
public class GamePane extends JPanel implements ActionListener, KeyListener {// *change
// GamePane
// to
// GamePane
// This is were the game screen is made and the player is created.
static final long serialVersionUID = 1L;
JLabel player = new JLabel();
JLabel finish = new JLabel();
JFrame gameFrame;
int playerSpeed = 4;
int FPS = 40;
// This array holds my JLabels for the walls.I used it so that i can have a
// for loop with an index for the labels.
JLabel[] walls = new JLabel[3];
{
walls[0] = new JLabel();
walls[1] = new JLabel();
walls[2] = new JLabel();
}
private final Set<Integer> keys = new HashSet<>();
// The keys set holds the keys being pressed
public static void main(String[] args) {
// Open the GUI window
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
// Create a new object and
// run its go() method
new GamePane().go();
}
});
}
GamePane() {
// Run the parent class constructor
super();
// Allow the panel to get focus
setFocusable(true);
// Don't let keys change the focus
}
/**
* This method creates the gameFrame and sets its layout to a cardlayout.It
* then proceeds the set up the GameFrame.The gameFrame contains the button
* pane and the gameStage
*
* The walls are an array and are used to create an index which is then used
* for the collisions.I set up the walls location here
*/
protected void go() {
setLayout(new CardLayout());
// Setup the window
gameFrame = new JFrame();
// Add this panel to the window
gameFrame.setLayout(new CardLayout());
gameFrame.add(this, "main");
gameFrame.setContentPane(this);
// Set's the window properties
gameFrame.setTitle("main");
gameFrame.setSize(800, 600);
gameFrame.setResizable(false);
gameFrame.setLocationRelativeTo(null);
gameFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
gameFrame.setVisible(true);
gameFrame.add(new ButtonPane(gameFrame), "buttons");
// Creates the new JPanel that will hold the game.
JPanel gamestage = new JPanel();
gamestage.setBackground(Color.darkGray);
gameFrame.add(gamestage, "game");
gamestage.setLayout(null);
// *Move the setup of the player and the timer under the walls
// Get a sample of collisions going so that i can do it over the weekend
// Setup the movable box
player.setBounds(25, 25, 20, 20);
player.setVisible(true);
player.setBackground(Color.red);
// Opaque makes the background visible
player.setOpaque(true);
// Setup the key listener
addKeyListener(this);
// Null layout allows moving objects!!!
gamestage.add(player);
// Set the timer
Timer tm = new Timer(1000 / FPS, this);
tm.start();
walls[0].setBounds(10, 15, 10, 480);// left height
walls[0].setVisible(true);
walls[0].setBackground(Color.white);
walls[0].setOpaque(true);
gamestage.add(walls[0]);
walls[1].setBounds(10, 10, 490, 10);// top width
walls[1].setVisible(true);
walls[1].setBackground(Color.white);
walls[1].setOpaque(true);
gamestage.add(walls[1]);
// wall3.setBounds(x, y, width, height);
walls[2].setBounds(10, 100, 100, 10);
walls[2].setVisible(true);
walls[2].setBackground(Color.white);
walls[2].setOpaque(true);
gamestage.add(walls[2]);
finish.setBounds(30, 455, 20, 20); // *make the game change to the main
// screen when finished
// Add a timer
finish.setVisible(true);
finish.setBackground(Color.LIGHT_GRAY);
finish.setOpaque(true);
gamestage.add(finish);
}
/**
* Check if two JLabel objects are touching
*
* @param a
* The first JLabel
* @param b
* The second JLabel
* @return true if the JLabels are touching
*/
public boolean areColliding(JLabel a, JLabel b) {
return a.getBounds().intersects(b.getBounds());
}
/**
* this method makes the player move. It takes the players speed and
* subtracts or adds the player speed to the current position of the player.
* It also figures out were the player is at currently aswell.
*
* @param arg0
*/
@Override
public void actionPerformed(ActionEvent arg0) {
// Move up if W is pressed
if (keys.contains(KeyEvent.VK_W)) {
player.setLocation(player.getX(), player.getY() - playerSpeed);
}
// Move right if D is pressed
if (keys.contains(KeyEvent.VK_D)) {
player.setLocation(player.getX() + playerSpeed, player.getY());
}
// Move down if S is pressed
if (keys.contains(KeyEvent.VK_S)) {
player.setLocation(player.getX(), player.getY() + playerSpeed);
}
// Move left if A is pressed
if (keys.contains(KeyEvent.VK_A)) {
player.setLocation(player.getX() - playerSpeed, player.getY());
}
for (int i = 0; i < walls.length; i++) {
// I created a for loop instead
// of a do loop because the for
// loop would have been a lot
// simpler to manage
if (areColliding(walls[i], player)) { // Reposition the target
int newX = (int) (25);
int newY = (int) (25);
player.setLocation(newX, newY);
}
}
if (areColliding(finish, player)) {
// Reposition the target
int newX = 25;
int newY = 25;
player.setLocation(newX, newY);
CardLayout layout = (CardLayout) gameFrame.getContentPane()
.getLayout();
layout.show(gameFrame.getContentPane(), "buttons");
}
}
@Override
public void keyPressed(KeyEvent e) {
// Add the key to the list
// of pressed keys
if (!keys.contains(e.getKeyCode())) {
keys.add(e.getKeyCode());
}
}
@Override
public void keyReleased(KeyEvent e) {
// Remove the key from the
// list of pressed keys
keys.remove((Integer) e.getKeyCode());
}
@Override
public void keyTyped(KeyEvent e) {
}
}
此代码在按下按钮时显示游戏窗格
/**
* This pane contains the button and sets up the button pane
*/
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ButtonPane extends JPanel {
private JButton startBTN;// Calls the JButton
JFrame game;
public ButtonPane(JFrame g) {
game = g;
setLayout(new GridBagLayout());
setBackground(Color.gray);// Sets the menu stages color blue
startBTN = new JButton("Game");// Creates a new button
add(startBTN);// Adds the button on the startStage
startBTN.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (game.getContentPane().getLayout() instanceof CardLayout) {
CardLayout layout = (CardLayout) getParent().getLayout();
layout.show(game.getContentPane(), "game");
}
}
});
}
}
解决方案
好的,所以你已经有了一个Timer
,它有时每秒都在滴答作响1000/FPS
,很酷。您真正需要的只是计算两个时间点之间的差异,令人惊讶的是,这非常简单。
首先定义一个“开始时间”
private Instant startTime;
null
直到你需要它。当您想启动计时器时,请使用startTime = Instant.now();
什么时候startTime != null
,你想计算它和现在之间的差异......
Duration runningTime = Duration.between(startTime, Instant.now());
这现在告诉您计时器已经运行了多长时间。
接下来,我们需要做出一些决定,比如当计时器用完时要做什么,但为此,我们实际上需要知道计时器应该运行多长时间......
private Duration timeOutDuration = Duration.ofSeconds(5);
这只是设置了 5 秒的超时,你可以使用你想要的任何范围。
这让我们可以计算计时器的剩余时间......
Duration timeRemainig = timeOutDuration.minus(runningTime);
然后决定做什么...
if (timeRemainig.isNegative() || timeRemainig.isZero()) {
// Time has run out...
// startTime = null; // stop the timer
} else {
// Update the UI
}
Java 8 中引入的日期/时间 API 非常强大和灵活(当您了解它时会非常有趣)
一个解决方案可能开始看起来像......
private Duration timeOutDuration = Duration.ofSeconds(5);
private Instant startTime; // Set this when you're ready to start the timer
@Override
public void actionPerformed(ActionEvent arg0) {
if (startTime != null) {
Duration runningTime = Duration.between(startTime, Instant.now());
Duration timeRemainig = timeOutDuration.minus(runningTime);
if (timeRemainig.isNegative() || timeRemainig.isZero()) {
// Time has run out...
// startTime = null; // stop the timer
} else {
// Update the UI
}
}
格式化Duration
输出通常看起来像......
long hours = timeRemainig.toHours();
long mins = timeRemainig.minusHours(hours).toMinutes();
// Or if you're lucky enough to be using Java 9+
//String formatted = String.format("%dhrs %02dmins", duration.toHours(), duration.toMinutesPart());
String formatted = String.format("%dhrs %02dmins", hours, mins);
或类似,取决于您希望它的格式
为什么使用这种方法而不是一些“计数器”
很简单,它(超级)准确。 Timer
仅保证“至少”间隔,也就是说,它将延迟不少于应用的值,这意味着随着时间的推移可能会引入“拖动”,此时计数器会不同步。当然,在短时间内,这可能没什么大不了的,但是既然有一个(超级简单)更好的方法来做到这一点,为什么不利用它呢。
该解决方案也非常灵活,适用于广泛的类似问题。我将上述概念用作基于时间的动画的一部分,这通常会产生更出色的整体效果。
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