编译通过，但运行时出现NoClassDefFoundError，是怎么回事

Question

看一下Complex.class文件是否在当前目录下
或者是你在其中定义了包

Answer 1

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;public class Complex
{
float realPart;
float imagePart; Complex(){realPart=0;imagePart=0;} //构造函数一 Complex(float real,float image) //构造函数
{
realPart=real;
imagePart=image;
} public void showMe()
{
System.out.print(this.realPart);
if(this.imagePart==0)
System.out.print("");
else if(this.imagePart>0)
{
System.out.print("+");
System.out.print(this.imagePart);
System.out.print("i");
}
else
{
System.out.print(this.imagePart);
System.out.print("i");
}
}
public Complex add(Complex A,Complex B) //两个复数相加
{
Complex C=new Complex();
C.realPart=A.realPart+B.realPart;
C.imagePart=A.imagePart+B.imagePart;
return C;
} public Complex sub(Complex A,Complex B)
{
Complex C=new Complex();
C.realPart=A.realPart-B.realPart;
C.imagePart=A.imagePart-B.imagePart;
return C;
} public Complex mul(Complex A,Complex B)
{
Complex C=new Complex();
C.realPart=A.realPart*B.realPart-A.imagePart*B.imagePart;
C.imagePart=A.realPart*B.imagePart+A.imagePart*B.realPart;
return C;
} public static void main(String args[])
{
float real=0,image=0;
Complex C1,C2;
BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入复数C1的实部：");
try
{
real=Float.parseFloat(reader.readLine());
}
catch(IOException e){}
System.out.println("请输入复数C1的虚部：");
try
{
image=Float.parseFloat(reader.readLine());
}
catch(IOException e){}
C1=new Complex(real,image); System.out.println("请输入复数C2的实部：");
try
{
real=Float.parseFloat(reader.readLine());
}
catch(IOException e){}
System.out.println("请输入复数C2的虚部：");
try
{
image=Float.parseFloat(reader.readLine());
}
catch(IOException e){}
C2=new Complex(real,image); System.out.println("C1=");
C1.showMe();
System.out.println("C2=");
C2.showMe();
}
}

Answer 2

zijibense(自己本色)：
这个贴子不用回复了，我已找到问题，把当前目录“.”加进ClassPath就行了。虽然 zijibense(自己本色)没回复什么，但他叫我把代码贴出来，这份热心难得。