用java编写一个图形化界面应用程序

[旺仔小子]

本人java入门级菜鸟，想求教各位大神如何用java编写一个图形化界面应用程序，用来计算三角形面积，由用户输入三遍长，若按空格则三边数值清空，按回车确定光标跳至下一条边输入框，三边输完即可出现三角形面积及缩略图，求赐教。。。

[topzergling]

import java.awt.GridLayout;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.SwingConstants;

public class MainFrame extends JFrame {
	private JTextField length1;
	private JTextField length2;
	private JTextField length3;
	private JTextField array[];

	public MainFrame() {
		init();
	}

	private void init() {
		length1 = createTextField("1");
		length2 = createTextField("2");
		length3 = createTextField("3");
		array = new JTextField[3];
		array[0] = length1;
		array[1] = length2;
		array[2] = length3;
		this.setLayout(new GridLayout(3, 2));
		this.add(new JLabel("边长A", SwingConstants.CENTER));
		this.add(length1);
		this.add(new JLabel("边长B", SwingConstants.CENTER));
		this.add(length2);
		this.add(new JLabel("边长C", SwingConstants.CENTER));
		this.add(length3);
		this.setSize(200, 150);
		this.setTitle("计算三角形面积");
		this.setVisible(true);
		this.setDefaultCloseOperation(EXIT_ON_CLOSE);
	}

	private JTextField createTextField(String name) {
		final JTextField t = new JTextField(6);
		t.setName(name);
		t.addKeyListener(new KeyListener() {

			@Override
			public void keyTyped(KeyEvent arg0) {
			}

			@Override
			public void keyReleased(KeyEvent arg0) {
			}

			@Override
			public void keyPressed(KeyEvent arg0) {
				if (arg0.getKeyCode() == KeyEvent.VK_SPACE) {
					clear();
					length1.grabFocus();
				} else if (arg0.getKeyCode() == KeyEvent.VK_ENTER) {
					if (check()) {
						JOptionPane
								.showMessageDialog(MainFrame.this, getArea());
					} else {
						JOptionPane.showMessageDialog(MainFrame.this,
								"请完整填写数据或者三条边无法构成三角形！");
					}
				}
			}

		});
		return t;
	}

	private Object getArea() {
		return 123;
	}

	private void clear() {
		length1.setText("");
		length2.setText("");
		length3.setText("");
	}

	private boolean check() {
		for (JTextField t : array) {
			if (!t.getText().matches("^[0-9]+$")) {
				return false;
			}
		}
		int x = Integer.parseInt(length1.getText());
		int y = Integer.parseInt(length2.getText());
		int z = Integer.parseInt(length3.getText());
		if (x + y < z || x + z < y || y + z < x)
			return false;
		return true;
	}

	public static void main(String[] args) {
		new MainFrame();
	}
}

空格是清空 回车是校验并提交 换行的功能还是tab
计算面积的函数是getArea()自己往里写吧
由于对正则表达式不熟，现在只能输入正整数

[桃园闲人]

楼上的很有耐心，支持！！！

[小绵羊]

已知三边的情况下用海伦公式计算

int a = 3, b = 4, c = 5;//三邊長
int p = (a + b + c) / 2;//半周長
Math.sqrt(p * (p - a) * (p - b) * (p - c));//面積