1、使用组件，制作一元二次方程求根的系统，要求：

（1）给出一元二次议程的3个系数a，b，c的输入界面。

（2）显示检查判别式的值。

（3）显示求出的根。

 http://s9/middle/6b9083fdgf8ac7fd77a88&690

import java.awt.BorderLayout;
import javax.swing.JPanel;
import javax.swing.JFrame;
import java.awt.Dimension;
import javax.swing.JLabel;
import java.awt.Rectangle;
import javax.swing.JTextField;
import javax.swing.JPasswordField;
import javax.swing.JButton;
import java.awt.Font;

public class Root extends JFrame {

 private static final long serialVersionUID = 1L;
 private JPanel jContentPane = null;
 private JLabel jLabel1 = null;
 private JLabel jLabel2 = null;
 private JLabel jLabel3 = null;
 private JTextField jTextField = null;
 private JTextField jTextField1 = null;
 private JTextField jTextField2 = null;
 private JButton jButton = null;
 private JLabel jLabel4 = null;
 private JTextField jTextField3 = null;
 private JLabel jLabel5 = null;
 private JTextField jTextField4 = null;
 private JLabel jLabel6 = null;
 private JTextField jTextField5 = null;
 private JTextField jTextField6 = null;
 
 public Root() {
  super();
  initialize();
 }

 
 private void initialize() {
  this.setSize(384, 241);
  this.setContentPane(getJContentPane());
  this.setTitle("解一元二次方程的根");
 }

 
 private JPanel getJContentPane() {
  if (jContentPane == null) {
   jLabel6 = new JLabel();
   jLabel6.setBounds(new Rectangle(17, 160, 75, 42));
   jLabel6.setText("方程的根X2");
   jLabel5 = new JLabel();
   jLabel5.setBounds(new Rectangle(17, 116, 75, 40));
   jLabel5.setFont(new Font("宋体", Font.BOLD, 12));
   jLabel5.setText("方程的根X1");
   jLabel4 = new JLabel();
   jLabel4.setBounds(new Rectangle(146, 73, 112, 35));
   jLabel4.setFont(new Font("Dialog", Font.BOLD, 18));
   jLabel4.setText(" 判别式的值");
   jLabel3 = new JLabel();
   jLabel3.setBounds(new Rectangle(256, 29, 53, 34));
   jLabel3.setFont(new Font("宋体", Font.BOLD, 24));
   jLabel3.setText("  c");
   jLabel2 = new JLabel();
   jLabel2.setBounds(new Rectangle(116, 24, 62, 30));
   jLabel2.setFont(new Font("宋体", Font.BOLD, 24));
   jLabel2.setText("  b");
   jLabel1 = new JLabel();
   jLabel1.setBounds(new Rectangle(4, 25, 52, 29));
   jLabel1.setFont(new Font("宋体", Font.BOLD, 24));
   jLabel1.setText("  a");
   jContentPane = new JPanel();
   jContentPane.setLayout(null);
   jContentPane.setFont(new Font("宋体", Font.PLAIN, 18));
   jContentPane.add(jLabel1, null);
   jContentPane.add(jLabel2, null);
   jContentPane.add(jLabel3, null);
   jContentPane.add(getJTextField(), null);
   jContentPane.add(getJTextField1(), null);
   jContentPane.add(getJTextField2(), null);
   jContentPane.add(getJButton(), null);
   jContentPane.add(jLabel4, null);
   jContentPane.add(getJTextField3(), null);
   jContentPane.add(jLabel5, null);
   jContentPane.add(getJTextField6(), null);
   jContentPane.add(getJTextField4(), null);
   jContentPane.add(jLabel6, null);
   jContentPane.add(getJTextField5(), null);
  }
  return jContentPane;
 }

 
 private JTextField getJTextField() {
  if (jTextField == null) {
   jTextField = new JTextField();
   jTextField.setBounds(new Rectangle(62, 24, 44, 33));
   jTextField.setText("");
  }
  return jTextField;
 }

 
 private JTextField getJTextField1() {
  if (jTextField1 == null) {
   jTextField1 = new JTextField();
   jTextField1.setBounds(new Rectangle(189, 28, 54, 33));
  }
  return jTextField1;
 }

 
 private JTextField getJTextField2() {
  if (jTextField2 == null) {
   jTextField2 = new JTextField();
   jTextField2.setBounds(new Rectangle(324, 27, 44, 37));
  }
  return jTextField2;
 }

 
 private JButton getJButton() {
  if (jButton == null) {
   jButton = new JButton();
   jButton.setBounds(new Rectangle(28, 67, 82, 40));
   jButton.setText("解方程");
   jButton.addActionListener(new java.awt.event.ActionListener() {
    public void actionPerformed(java.awt.event.ActionEvent e) {
     
     double a=Integer.parseInt(jTextField.getText());
     double b=Integer.parseInt(jTextField1.getText());
     double c=Integer.parseInt(jTextField2.getText());
     double d=b*b-4*a*c;
     String s = String.valueOf(d);
     jTextField3.setText(s);
     double g=(-b+Math.sqrt(d))/(2*a);
     double h=(-b-Math.sqrt(d))/(2*a);
     
     
     if(d<0) {jTextField4.setText("没有实数根！！");
     jTextField5.setText("没有实数根！！");}
     
     
     
     if(d==0) {jTextField4.setText("x1="+g);
     jTextField5.setText("x2="+g);}
     
     if(d>0) {jTextField4.setText("x1="+g);
     jTextField5.setText("x2="+h);
     }
     
     
     // TODO Auto-generated Event stub actionPerformed()
    }
   });
  }
  return jButton;
 }

 
 private JTextField getJTextField3() {
  if (jTextField3 == null) {
   jTextField3 = new JTextField();
   jTextField3.setBounds(new Rectangle(280, 74, 75, 37));
  }
  return jTextField3;
 }

 
 private JTextField getJTextField4() {
  if (jTextField4 == null) {
   jTextField4 = new JTextField();
   jTextField4.setBounds(new Rectangle(113, 115, 212, 38));
  }
  return jTextField4;
 }

 
 private JTextField getJTextField5() {
  if (jTextField5 == null) {
   jTextField5 = new JTextField();
   jTextField5.setBounds(new Rectangle(112, 162, 211, 38));
  }
  return jTextField5;
 }

 
 private JTextField getJTextField6() {
  if (jTextField6 == null) {
   jTextField6 = new JTextField();
  }
  return jTextField6;
 }

}  //  @jve:decl-index=0:visual-constraint="66,32"