我有一个应用程序,它用Java编程的极坐标做事。我必须为它创建一个GUI,我决定尝试使用swing组件而不是这个称为BreezyGUI的JAR。我遇到的问题是我无法设置框架选项而不会出错。创建框架、标签和文本字段后,如何开始设计界面?任何建议都会对我有所帮助,谢谢!
我在 Eclipse 中收到的错误并不具体。它只是将其突出显示为红色,就像它是直接错过类型一样。
这是我的应用程序:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.text.*;
public class PolarCoords extends JFrame
{
JFrame frameWin = new JFrame();
frameWin.setBounds(100, 200, 120, 120);
frameWin.setTitle("Polar Coordinates");
frameWin.setVisible(true);
frameWin.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
private JLabel rLabel;
private JLabel thetaLabel;
private JLabel r2Label;
private JLabel theta2Label;
private JLabel answerLabel;
private static String rString = "R Coordinate";
private static String thetaString = "Theta";
private static String r2String = "R2 Coordinate";
private static String theta2String = "Theta2";
private static String answerString = "Answer";
private JFormattedTextField rField;
private JFormattedTextField thetaField;
private JFormattedTextField r2Field;
private JFormattedTextField theta2Field;
private JFormattedTextField answerField;
public PolarCoords(double rCoord, double theta)
{
return;
}
/**
* Returns theta in (r, theta)
* @param tTheta
* @return
*/
public double tTheta(double theta)
{
return theta;
}
/**
* Returns r coordinate in (r, theta)
* @param rCoord
* @return
*/
public double rRCoord(double rCoord)
{
return rCoord;
}
public Object magnitude()
{
double r1 = Double.valueOf(rField.getText());
double theta1 = Double.valueOf(thetaField.getText());
double r2 = 0;
double theta2 = 0;
double distance = Math.sqrt(Math.pow(r1, 2)) + Math.sqrt(Math.pow(r2, 2) - 2*(r1*r2) * Math.cos(theta1 - theta2));
return distance;
}
public Double angleFromOrigin()
{
double theta1 = Double.valueOf(thetaField.getText());
double theta2 = Double.valueOf(theta2Field.getText());
double answer = theta2 - theta;
return answer;
}
public Object distanceFromPoint()
{
// Distance formula Ã(r1)^2 + (r2)^2 - 2(r1)(r2) cos ( degree1 - degree2 )
double r1 = Double.valueOf(rField.getText());
double theta1 = Double.valueOf(thetaField.getText());
double r2 = Double.valueOf(r2Field.getText());
double theta2 = Double.valueOf(theta2Field.getText());
double distance = Math.sqrt(Math.pow(r1, 2)) + Math.sqrt(Math.pow(r2, 2) - 2*(r1*r2) * Math.cos(theta1 - theta2));
return distance;
}
public PolarCoords addPoints()
{
double r1 = Double.valueOf(rField.getText());
double theta1 = Double.valueOf(thetaField.getText());
double r2 = Double.valueOf(r2Field.getText());
double theta2 = Double.valueOf(theta2Field.getText());
double x = r1 * Math.cos(theta1);
double y = r1 * Math.sin(theta1);
double x2 = r2 * Math.cos(theta1);
double y2 = r2 * Math.sin(theta2);
double xAnswer = x2 - x;
double yAnswer = y2 - y;
double answer = Math.atan2(xAnswer, yAnswer);
PolarCoords polarAnswer = new PolarCoords(xAnswer, yAnswer);
return polarAnswer;
}
public static void main(String[] args)
{
Frame f = new Frame();
System.out.print("Visible = True");
}
}
您正在尝试将 Java 语句裸露地放置在类中,在构造函数或方法之外,这不起作用。请考虑将这些语句放在构造函数中。更重要的是,通过Java教程的介绍,因为在尝试进行Swing GUI编码之前,您确实应该了解基础知识。
此外,您忽略了表示this
对象的 JFrame,并尝试创建一个完全不相关的 JFrame 对象。别这样。摆脱frameWin变量,因为它只会误导你。
再次阅读Java的基础知识,因为这将极大地帮助您。
请查看 Java 教程真正大索引
//JFrame frameWin = new JFrame();
frameWin.setBounds(100, 200, 120, 120);
frameWin.setTitle("Polar Coordinates");
frameWin.setVisible(true);
frameWin.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE) ;
应该在方法内。当你扩展JFrame时,它必须是
setBounds(100, 200, 120, 120);
setTitle("Polar Coordinates");
setVisible(true);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE) ;
您可以这样做:
public class PolarCoords extends JFrame
{
public PolarCoords()
{
setBounds(100, 200, 120, 120);
setTitle("Polar Coordinates");
setVisible(true);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE) ;
}
}
或
public class PolarCoords extends JFrame
{
public PolarCoords()
{
Init();
}
public void Init()
{
setBounds(100, 200, 120, 120);
setTitle("Polar Coordinates");
setVisible(true);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE) ;
}
}
为什么frameWin
被注释掉了,而你仍然在后续行中使用它???你的意思是使用this
吗?该部分应位于构造函数中。
此外,将所有组件添加到框架后,setvisible
应该是最后一件事。
尝试:
public PolarCoords(double rCoord, double theta) //u'r not even using rCoord and theta
{
this.setBounds(100, 200, 120, 120);
this.setTitle("Polar Coordinates");
this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
this.setVisible(true);
}