Exception in thread "main" java.lang.NullPointerException at ysuan.main(ysuan.java:70)是什么意思?
来源:百度知道 编辑:UC知道 时间:2024/06/25 05:54:55
public class ysuan{
public static void main(String args[])throws IOException{
int i;
int Num=0,num=0;//num记录运算符号个数,比较num和Num判断是否已经提取运算符号
char []fh=new char[2];//存放运算符号
int []fhnum=new int[2];//记录两个运算符号的位置
StringBuffer [] str=new StringBuffer[3];
byte []e=new byte[30];
System.out.println("输入算式表达式:");
int len=System.in.read(e);
String biaodashi=new String(e,0,len-2);
char[] chars = biaodashi.toCharArray();
for (i=0; i < chars.length; i++) {
if(chars[i]=='+'){ fh[num]='+';fhnum[num]=i;num++;}
else if(chars[i]=='-'){ fh[num]='-'; fhnum[num]=i;num++;}
else if(chars[i]=='/'){ fh[num]='/';fhnum[num]=i ;num++;}
else if(chars[i]=='*'){ fh[num]='*';fhnum[num]=i ;num++;}
else
{if(Num<num) Num++;
public static void main(String args[])throws IOException{
int i;
int Num=0,num=0;//num记录运算符号个数,比较num和Num判断是否已经提取运算符号
char []fh=new char[2];//存放运算符号
int []fhnum=new int[2];//记录两个运算符号的位置
StringBuffer [] str=new StringBuffer[3];
byte []e=new byte[30];
System.out.println("输入算式表达式:");
int len=System.in.read(e);
String biaodashi=new String(e,0,len-2);
char[] chars = biaodashi.toCharArray();
for (i=0; i < chars.length; i++) {
if(chars[i]=='+'){ fh[num]='+';fhnum[num]=i;num++;}
else if(chars[i]=='-'){ fh[num]='-'; fhnum[num]=i;num++;}
else if(chars[i]=='/'){ fh[num]='/';fhnum[num]=i ;num++;}
else if(chars[i]=='*'){ fh[num]='*';fhnum[num]=i ;num++;}
else
{if(Num<num) Num++;
类ysuan中主函数main存在访问空对象(null)的异常
空指针异常
NullPointerException at ysuan.main(ysuan.java:70)
空指针错误,你查看一下代码 第70行看看调用了那些对象,然后这些有没有对应的\'NEW\'一下呢!
Exception EOleSysError in module
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