Read ecuations from file

[drunkkiller]

I need to make a function in java that read some stuff from a file .
This is what i need to read :

n= 3
( 432 + x^4 + y^4 - 2z^4 + y^2 * z^2 ) / 234
( 324 - x^4 + 2y^4 - 3z^4 + 3x^2 * z^2 ) / 432
( 234 + 2x^4 - 3y^4 + 4z^4 - x^2 * y^2 + 3x + y ) / 324
x0= 0 0 0,5
q= 0,33
E= 10^-10

It's some values and some ecuations .

This is what i coded so far :

    public  void ReadFile() throws FileNotFoundException
  {  
    try{       
Scanner fis = new Scanner( new FileInputStream("input.txt"));

if("n=".equals(fis.next("n="))==true ) 
  {   
 n=Integer.parseInt(fis.next());
 System.out.println("n=" + n);
  }
while(fis.hasNext())   
{  
matrix.add(new ArrayList());
  ((ArrayList)matrix.get(0)).add(fis.next());
 
}

for(i=0;i< matrix.size();i++){
 for(j=0;j< ((ArrayList)matrix.get(i)).size();j++) {
System.out.print( ((ArrayList)matrix.get(0)).get(j) + " ");
 }// System.out.println();
}
    
    }
  catch( IOException ioException) {
  throw new RuntimeException("File not found !");}
  }

Any ideas how to to this ?I created an Array list where a want to put all the ecuations .

[JosAH]

Do you need those formulas as just Strings or do you need them as if they are real expressions?

kind regards,

Jos

[drunkkiller]

I need them to do some mathematical stuff ,so real expressions .

[JosAH]

Well, you're in quite some work then: you either have to write an almost complete formula/expression parser (also see my blog entry on expression compilers) or you have to include a script interpreter such as the included Javascript engine. Both have their pros and cons. There is no free lunch here.

kind regards,

Jos

[drunkkiller]

I reached a impas with my project. I read the expressions in a ArrayList called "matrix" and for mathematical operations i copy the Arraylist into another ArrayList called "clone" . Why when the statements at lines 33, 34,35 are executed affects both ArrayLists ?
I didn't posted all my code because is ~550 lines

ArrayList matrix= new ArrayList () ;
   ArrayList clone =new ArrayList();
  ....
//-----------------------------------------------
 i=0;                                           
matrix.add(new ArrayList());
clone.add(new ArrayList());

while(fis.hasNext())   
{  
aux=fis.next();                                

  if("end".equals(aux)==true)                  //this is where i read the ecuations
    {    i++;
        clone.add(new ArrayList());
        matrix.add(new ArrayList());
        aux=fis.next();}
  
  ((ArrayList)matrix.get(i)).add(aux);
 }
    }
//-----------------------------------------------------------------

public Double calcExp(int poz)
   {
       suma=0;
     Collections.copy(clone,matrix); // i need to copy matrix into clone every time this function is called

        for(j=0;j< ((ArrayList)clone.get(poz)).size();j++)
       {
           if("^".equals( ((ArrayList)clone.get(poz)).get(j)) && ")".equals( ((ArrayList)clone.get(poz)).get(j-1))==false)
           {  
             ((ArrayList)clone.get(poz)).set(j,calcExpPow(poz,j)); //calcExpPow returns a double
             ((ArrayList)clone.get(poz)).remove(j+1);
             ((ArrayList)clone.get(poz)).remove(j-1);
             j--;
              
          System.out.println("pow");
        this.Display(clone);  
           }
          
         System.out.println("  ^");
         this.Display(matrix);//this shouldn't change but displays same elements like clone
   }
...
return suma;
}
//--------------------------------------------------------