我正在创建一个简单的 Java 圆形计算器，但在让我的 KeyListeners 快速响应时遇到问题。Circle 类中的 x 和 y 值不会立即存储，而是在我删除输入时存储。例如，如果我为 x 输入 3，为 y 输入 5，Circle 类将返回值 0，直到我删除这些值，然后它将返回正确的值。我的目标是在用户输入值时立即显示与此坐标相关的数据。当 KeyListeners 滞后时，我不能这样做。谢谢你。
**编辑：刚刚意识到，如果我之后按另一个键（例如 ctrl），这些值也将是正确的
**第二次编辑：在底部添加了圈子代码
**第三次编辑：在底部添加点代码
这是我的代码：
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.text.DecimalFormat;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class CircleGUI extends JFrame
{
Circle c;
JFrame frame;
DecimalFormat df;
private JPanel panel;
private JLabel radiusLabel, areaLabel, coordinateLabel, containsPointLabel;
private JButton calculateButton;
private JTextField radiusTextField, xTextField, yTextField;
final int WINDOW_WIDTH = 500;
final int WINDOW_HEIGHT = 300;
public static void main(String[] args)
{
Circle c = new Circle();
CircleGUI test = new CircleGUI(c);
}
public CircleGUI(Circle c)
{
this.c = c;
setTitle("Circle Calculator");
setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
buildPanel();
add(panel);
df = new DecimalFormat("#.##");
setVisible(true);
}
private JPanel buildPanel()
{
radiusLabel = new JLabel("Enter radius:");
areaLabel = new JLabel();
radiusTextField = new JTextField(15);
calculateButton = new JButton("Calculate Area");
calculateButton.addActionListener(new CalculateAreaButtonListener());
coordinateLabel = new JLabel("Origin of the Circle:");
containsPointLabel = new JLabel("");
xTextField = new JTextField(4);
xTextField.addKeyListener(new xCoordinateTextFieldListener());
yTextField = new JTextField(4);
yTextField.addKeyListener(new yCoordinateTextFieldListener());
panel = new JPanel();
//panel.setLayout(new FlowLayout());
panel.add(radiusLabel);
panel.add(radiusTextField);
panel.add(calculateButton);
panel.add(areaLabel);
panel.add(coordinateLabel);
panel.add(xTextField);
panel.add(yTextField);
panel.add(containsPointLabel);
return panel;
}
private class CalculateAreaButtonListener implements ActionListener
{
@Override
public void actionPerformed(ActionEvent e)
{
areaLabel.setText(String.valueOf(df.format(calculateArea())));
}
public double calculateArea()
{
double radius = Double.parseDouble(radiusTextField.getText());
c.setRadius(radius);
return c.getArea();
}
}
private class xCoordinateTextFieldListener implements KeyListener
{
@Override
public void keyPressed(KeyEvent e)
{
double x;
if (!xTextField.getText().equals(null) && !xTextField.getText().equals(""))
{
x = Double.parseDouble(xTextField.getText());
c.setX(x);
}
}
@Override
public void keyReleased(KeyEvent e)
{
System.out.println("x: " + c.getX());
}
@Override
public void keyTyped(KeyEvent arg0)
{
}
}
private class yCoordinateTextFieldListener implements KeyListener
{
@Override
public void keyPressed(KeyEvent e)
{
double y;
if (!yTextField.getText().equals(null) && !yTextField.getText().equals(""))
{
y = Double.parseDouble(yTextField.getText());
c.setY(y);
}
;
}
@Override
public void keyReleased(KeyEvent e)
{
System.out.println("y: " + c.getY());
}
@Override
public void keyTyped(KeyEvent arg0)
{
}
}
}
圈子代码：
public class Circle
{
//Instantiate and declare instance fields
Point origin = new Point();
double radius;
Circle(double radius)
{
this.radius = radius;
origin.setX(0);
origin.setY(0);
}
//Two arg-constructor
Circle(Point origin, double radius)
{
this.origin = origin;
this.radius = radius;
}
//Three-arg constructor
Circle(double xValue, double yValue, double radius)
{
origin.setX(xValue);
origin.setY(yValue);
this.radius = radius;
}
//Default constructor
Circle()
{
setX(0);
setY(0);
radius = 0;
}
//Copy constructor
Circle(Circle c)
{
setX(c.getX());
setY(c.getY());
radius = c.getRadius();
}
//Get origin of the circle
Point getOrigin()
{
return origin;
}
//Set origin of the circle
void setOrigin(Point point)
{
this.origin = point;
}
//Set x value
void setX(double x)
{
origin.setX(x);
}
//Get x value
double getX()
{
return origin.getX();
}
//Set y value
void setY(double y)
{
this.origin.setY(y);
}
//Get y value
double getY()
{
return origin.getY();
}
//Set radius field
void setRadius(double radius)
{
this.radius = radius;
}
//Get radius field
double getRadius()
{
return radius;
}
//Get area of the circle
double getArea()
{
//Use constant provided in the static method Math.PI
return Math.PI * (radius * radius);
}
//Translate instance fields to a human readable String
public String toString()
{
return "x: " + this.getX() + ", y: " + this.getY() + ", radius: " + this.radius;
}
//Compare whether two circles instance fields are equal
boolean equals(Circle c)
{
if (getX() == c.getX() && getY() == c.getY() && getRadius() == c.getRadius())
return true;
else
return false;
}
double getDistance(double xValue, double yValue)
{
double x = xValue - this.getX();
double y = yValue - this.getY();
return Math.sqrt((x * x) + (y * y));
}
double getDistance(Circle c)
{
//Initialize variables to x^2-x^1 and y^2-y^1
double x = c.getX() - this.getX();
double y = c.getY() - this.getY();
//Calculate distance to center of the circle
return Math.sqrt((x * x) + (y * y));
}
boolean containsPoint(double xValue, double yValue)
{
if (getDistance(xValue, yValue) <= radius)
return true;
else
return false;
}
//Test if two circle overlap
boolean doesOverlap(Circle c)
{
//Initialize sumOfRadii to the sum of both circles radius
double sumOfRadii = c.getRadius() + radius;
//If the distance to the center of the circle is less than or equal to the sum of the two circles radius then return true, otherwise return false.
if (getDistance(c) <= sumOfRadii)
return true;
else
return false;
}
}
点代码：
public class Point
{
private double x;
private double y;
public Point(double xValue, double yValue)
{
x = xValue;
y = yValue;
}
public Point(Point p) {
this(p.x, p.y);
}
public Point() {
this(0, 0);
}
public void setX(double xValue)
{
this.x = xValue;
}
public double getX()
{
return x;
}
public void setY(double yValue)
{
this.y = yValue;
}
public double getY()
{
return y;
}
public boolean equals(Point otherPoint)
{
return (this.x == otherPoint.x) && (this.y == otherPoint.y);
}
public String toString() {
return "(" + x + ", " + y + ")";
}
}