public Object intern ( Object keyArg ) { boolean nullKey = false ; if ( keyArg == null ) { nullKey = true ; keyArg = UniqueTag . NULL_VALUE ; } int index = ensureIndex ( keyArg ) ; values [ index ] = 0 ; return ( nullKey ) ? null : keys [ index ] ; }
If table already contains a key that equals to keyArg return that key while setting its value to zero otherwise add keyArg with 0 value to the table and return it .