code: public void setMode(int mode) {
          // check arg
          switch (mode) {
              case MODE_EXACT:
              case MODE_JCOMPOUNDMAPPER:
                  break;
              default:
                  throw new IllegalArgumentException("Invalid mode specified!");
          }
          this.mode = mode;
  
          // re-gen atom expressions
          int numAtoms = mol.getAtomCount();
          for (int atomIdx = 0; atomIdx < numAtoms; atomIdx++)
              this.aexpr[atomIdx] = encodeAtomExpr(atomIdx);
      }
docs: Set the mode of SMARTS substructure selection
  
  @param mode the mode