小编Puf*_*ure的帖子

所以我正在编写一个程序来解决二次方程式,并且在制作2个JLabel(以前为空)显示答案时,一切都有效(当用户单击JButton时会发生这种情况)

这是整个程序,因为我不知道错误在哪里.

import java.awt.event.*;

import javax.swing.*;


public class Third implements ActionListener {

    //--------------
    //Data Members
    //--------------
/**
 * Top level window 
 */
JFrame top;
/**
 * Changed into a string by ConvertToDouble(string str);
 */
double a, b, c; 
double answer1,answer2;
JTextField inputA, inputB, inputC;  
JLabel describeA, describeB, describeC, print1, print2;
JButton submit;
String aa, bb, cc;
String result1, result2;
String strA, strB, strC;




    public Third(){

    top = new JFrame("Ned's quadratic equation solver");
    top.setVisible(true);
    top.setLayout(null);
    top.setBounds(50,50,250,250);


    inputA = new JTextField(12);    
    inputA.setBounds(100,30,200,25); …