大家来帮我看看这个程序问题出在哪儿！

[boycq]

//源程序
import java.io.*;
import java.lang.Math;

class equation
{
private int a;
private int b;
private int c;
public equation()
{
try
{
System.out.print("请输入第一个系数:");
BufferedReader ba = new BufferedReader(new InputStreamReader(System.in));
String digit = ba.readLine();
this.a = Integer.parseInt(digit);

System.out.print("\n请输入第二个系数:");
BufferedReader bb = new BufferedReader(new InputStreamReader(System.in));
digit = bb.readLine();
this.b = Integer.parseInt(digit);

System.out.print("\n请输入第三个系数:");
BufferedReader bc = new BufferedReader(new InputStreamReader(System.in));
digit = bc.readLine();
this.c = Integer.parseInt(digit);
}
catch(IOException e)
{
System.out.println(e);
}
}
public void showEquation()
{
System.out.println("你输入的方程是："+a+"X*X"+"+"+b+"X"+"="+"0");
}
public void qiujieEquation()
{
double dir;
dir = (double)(b*b-4*a*c);
if(dir >= 0)
{
System.out.println("\n方程的根是:"+(-b+Math.sqrt(dir))/(2*a)+"和"+(-b-Math.sqrt(dir))/2*a);
}
else
{
System.out.println("\n此方程无解!");
}
}
}

public class Equation
{
public static void main(String[] args)
{
equation Eqt=new equation();
Eqt.showEquation();
Eqt.qiujieEquation();
}
}

编译通过，运行有错误
以下是错误提示：
java.lang.NoClassDefFoundError: equation (wrong name: Equation)
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at Equation.main(Equation.java:56)
Exception in thread "main"

[wuyafeixue]

我把第一个类名该成quation 就可以了，我觉得是两个类的名字只有大小写区别导致错误的

import java.io.*;
import java.lang.Math;

class quation
{
private int a;
private int b;
private int c;
public quation()
{
try
{
System.out.print("请输入第一个系数:");
BufferedReader ba = new BufferedReader(new InputStreamReader(System.in));
String digit = ba.readLine();
this.a = Integer.parseInt(digit);

System.out.print("\n请输入第二个系数:");
BufferedReader bb = new BufferedReader(new InputStreamReader(System.in));
digit = bb.readLine();
this.b = Integer.parseInt(digit);

System.out.print("\n请输入第三个系数:");
BufferedReader bc = new BufferedReader(new InputStreamReader(System.in));
digit = bc.readLine();
this.c = Integer.parseInt(digit);
}
catch(IOException e)
{
System.out.println(e);
}
}
public void showEquation()
{
System.out.println("你输入的方程是："+a+"X*X"+"+"+b+"X"+"="+"0");
}
public void qiujieEquation()
{
double dir;
dir = (double)(b*b-4*a*c);
if(dir >= 0)
{
System.out.println("\n方程的根是:"+(-b+Math.sqrt(dir))/(2*a)+"和"+(-b-Math.sqrt(dir))/2*a);
}
else
{
System.out.println("\n此方程无解!");
}
}
}

public class Equation
{
public static void main(String[] args)
{
quation Eqt=new quation();
Eqt.showEquation();
Eqt.qiujieEquation();
}
}