question: public JSONBuffer appendKeyValue ( Object key , Object val ) { if ( stack . empty ( ) || stack . peek ( ) != Operand . HASH ) { throw new JSONException ( "Appending key-value outside of hash context." ) ; } addQuotedString ( key ) ; buffer . append ( ":" ) ; if ( val instanceof Double ) { buffer . append ( val . toString ( ) ) ; } else if ( val instanceof Integer ) { buffer . append ( val . toString ( ) ) ; } else { addQuotedString ( val ) ; } buffer . append ( "," ) ; return this ; }
target:  Append a key-value pair as string.