What is the Java equivalent of C's if(!var)? [closed]

What does if(!var) do in C? I think I'll understand it more if someone told me what it's equivalent to in Java because I know more Java than C.

Here's an example. I don't understand what the condition does.

the flag is considered an int here. int i,flag=1,j;

 if(!flag)
       {
     for(j=0;j<n;j++);
      n++;
     Fnm[j]=nm;
     Fsz[j]=sz;
     strt[j]=F_start[i];
     F_start[i]+=sz;
    printf("\n After allocation of this file/process,The FAT will be =>> \n\n");
    dsp();
       }
      else
       printf("\nNo enough space.\n");