我在JavaFX中存在一个检测单个按键的问题。我需要检测箭头键,但每次我按这些键之一时,我的代码的某个部分都会被多次调用。我意识到这是因为AnimationTimer()
是一个循环,所以这就是原因,但我不知道如何检测单个按键击。无论如何,下面是代码:
import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.input.KeyEvent;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import java.util.HashSet;
public class Main extends Application {
Stage window;
static Scene scene;
private static char[][] mapa = {
{'X','X','X','X','X'},
{'X','.','.','.','X'},
{'X','.','M','.','X'},
{'X','.','.','.','X'},
{'X','X','X','X','X'}
};
private final int sizeX = 16;
private final int sizeY = 16;
static HashSet<String> currentlyActiveKeys;
@Override
public void start(Stage primaryStage) throws Exception {
window = primaryStage;
window.setTitle("Hello World");
Group root = new Group();
scene = new Scene(root);
window.setScene(scene);
Canvas canvas = new Canvas(512 - 64, 256);
root.getChildren().add(canvas);
prepareActionHandlers();
GraphicsContext gc = canvas.getGraphicsContext2D();
new AnimationTimer() {
@Override
public void handle(long now) {
gc.clearRect(0,0,512,512);
for(int i = 0; i < mapa.length; i++) {
for(int j = 0; j < mapa[i].length; j++) {
if(mapa[i][j] == 'X') {
gc.setLineWidth(5);
gc.setFill(Color.RED);
gc.fillRect(sizeX + i*sizeX, sizeY + j*sizeY, sizeX, sizeY);
} else if(mapa[i][j] == '.') {
gc.setLineWidth(5);
gc.setFill(Color.GREEN);
gc.fillRect(sizeX + i*sizeX, sizeY + j*sizeY, sizeX, sizeY);
} else if(mapa[i][j] == 'M') {
gc.setLineWidth(5);
gc.setFill(Color.BLACK);
gc.fillRect(sizeX + i*sizeX, sizeY + j*sizeY, sizeX, sizeY);
}
}
}
if(currentlyActiveKeys.contains("LEFT")) {
System.out.println("left");
}
if(currentlyActiveKeys.contains("RIGHT")) {
System.out.println("right");
}
if(currentlyActiveKeys.contains("UP")) {
System.out.println("up");
}
if(currentlyActiveKeys.contains("DOWN")) {
System.out.println("down");
}
}
}.start();
window.show();
}
private static void prepareActionHandlers()
{
currentlyActiveKeys = new HashSet<String>();
scene.setOnKeyPressed(new EventHandler<KeyEvent>() {
@Override
public void handle(KeyEvent event)
{
currentlyActiveKeys.add(event.getCode().toString());
}
});
scene.setOnKeyReleased(new EventHandler<KeyEvent>() {
@Override
public void handle(KeyEvent event)
{
currentlyActiveKeys.remove(event.getCode().toString());
}
});
}
public static void main(String[] args) {
launch(args);
}
}
当我按下箭头按钮时(其他按键当然也一样),在范围内我得到的结果如下:
down
down
down
down
down
down
很明显,只要我按下按钮,打印就会开始。一旦我停止按下它,打印就会结束。我想实现的是,只要我按下按钮(无论我持续多长时间),我就会得到一个 down 。我需要这样做,因为我想更新我的
canvas
中矩形的颜色。
setOnKeyPressed
。 - Lisek