问Java找不到符号？

package javaapplication6;

import java.util.*;

class JavaApplication6{

public static void main(String[] args){

Scanner xh=new Scanner(System.in);

int choice;

int a,b,c;

int i=0;

System.out.println("请输入一个初始值a:");

a=xh.nextInt();

System.out.println("请输入一个终止值b:");

b=xh.nextInt();

System.out.println("请输入一个等差值c:");

c=xh.nextInt();

System.out.println("请选择循环方式:");

do {

System.out.println("1.for;2.while 3.do while");

System.out.println("0.退出");

System.out.println("请输入你选择的方式的数字:");

choice=xh.nextInt();

fangshi xw=new fangshi();

switch (choice)

{

case 1: xw.choice_1( a, b, c);

break;

case 2: xw.choice_2(a,b,c);

break;

case 3: xw.choice_3(a,b,c);

break;

case 0: xw .choice_1(a,b,c);

System.out.println("已退出");

break;

default:

System.out.println("输入错误，请重新输入");

break;

}

}while(choice!=0);

}

}

class fnagshi {

int sum=0;

void choice_1(int a,int b,int c)

{

for(int j=a;j<=b;j+=c)

{

sum+=j;

}

System.out.println("for的结果为:"+sum);

}

void choice_2(int a,int b,int c)

{

int j=a;

while(j<=b)

{

sum+=j;

j+=c;

}

System.out.println("while的结果为:"+sum);

}

void choice_3(int a,int b,int c)

{int j=a;

do{

sum+=j;

j+=c;

}

while(j<=b);

System.out.println("do while的结果为:"+sum);

}

}

Compiling 1 source file to C:\Users\小委\Documents\NetBeansProjects\JavaApplication6\build\classes

C:\Users\小委\Documents\NetBeansProjects\JavaApplication6\src\javaapplication6\JavaApplication6.java:21: 错误: 找不到符号

fangshi xw=new fangshi();

符号: 类 fangshi

位置: 类 JavaApplication6

C:\Users\小委\Documents\NetBeansProjects\JavaApplication6\src\javaapplication6\JavaApplication6.java:21: 错误: 找不到符号

fangshi xw=new fangshi();

符号: 类 fangshi

位置: 类 JavaApplication6

2 个错误

C:\Users\小委\Documents\NetBeansProjects\JavaApplication6\nbproject\build-impl.xml:923: The following error occurred while executing this line:

C:\Users\小委\Documents\NetBeansProjects\JavaApplication6\nbproject\build-impl.xml:263: Compile failed; see the compiler error output for details.

构建失败 (总时间: 0 秒)