We propose a scheme for localizing an atom in a four-level configuration inside a classical standing wave field, conditioned upon the measurement of frequency of a weak probe field. In the classical standing wave field, the interaction between the atom and the field is position dependent due to the Rabi-frequency of the driving field. Hence, as the absorption frequency of the probe field is measured the position of the atom inside the classical standing wave field will be determined. Localizing of the atom via the absorption spectrum occurs during its motion in the standing wave field. The investigation of the probe field absorption shows that the degree of localization depends on the interaction parameters such as detuning, and Rabi-frequency of the driving field.