JAVA GUI算出台形面レベル

インタフェースを実行すると、以下の
、
新しい参照のために実行するために必要な教師
、次のようにコードは次のとおりです。
Textmain.java

public class textmain {
	public static void main(String args[]) {
		CalculateForm calculatefrom =new CalculateForm("使用MVC结构");
	}
}

CalculateForm.java

import java.awt.Button;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Label;
import java.awt.TextArea;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class CalculateForm extends Frame implements ActionListener{
	TextArea textarea=new TextArea();
	Label uppersole,bottom,hight;		//定义上底下底，高的Lable
	TextField textuppersole,textbottom,texthight;
	Button giveAnwser;
	
	CalculateForm(String s) {
		super(s);
		setLayout(new FlowLayout());
		textuppersole=new TextField(10);
		textbottom=new TextField(10);
		texthight=new TextField(10);
		uppersole=new Label("上底:");
		bottom=new Label("下底:");
		hight=new Label("高:");
		giveAnwser=new Button("计算面积");
		add(uppersole);
		add(textuppersole);
		add(bottom);
		add(textbottom);
		add(hight);
		add(texthight);
		add(giveAnwser);
		add(textarea);
		
		giveAnwser.addActionListener(this);  //将当前窗口注册为giveAnwser的ActionEvent事件监视器
		setBounds(100,100,540,250);
		setVisible(true);
		validate();
      	addWindowListener(new WindowAdapter(){
      		public void windowClosing(WindowEvent e){
      			System.exit(0);
      			}
      		}
      	);
	}

	@Override
	public void actionPerformed(ActionEvent e) {
		Trapezoid trapezoid=new Trapezoid(Double.parseDouble(textuppersole.getText()),Double.parseDouble(textbottom.getText()),Double.parseDouble(texthight.getText()));
		if(e.getSource()==giveAnwser) //判断事件源是否是giveAnwser 
	       { 
	          try{ 
	        	  textarea.append(trapezoid.getHight());
	        	  textarea.append(trapezoid.getBottom());
	        	  textarea.append(trapezoid.getHight());
	        	  textarea.append("的梯形面积为:");
	        	  textarea.append(Double.toString(trapezoid.getArea()));
	        	  textarea.append("\n");
	             }
	          catch(NumberFormatException ex){
	        	  
	             }
	       }
		
	}
}

Trapezoid.java

public class Trapezoid {
	double uppersole,bottom,hight,Area;
	Trapezoid(double uppersole,double bottom,double hight){
		this.uppersole=uppersole;
		this.bottom=bottom;
		this.hight=hight;
	}
	public String getUppersole() {
		return "上底为"+Double.toString(uppersole);
	}
	public String getBottom() {
		return "下底为"+Double.toString(bottom);
	}
	public String getHight() {
		return "上底为"+Double.toString(hight);
	}
	public double getArea() {
		return ((uppersole+bottom)*hight)/2;
	}
}