I want to create a polygon, which represents the administrative boundary of a city.
It is specified by a relation, which consists of ways
<member type="way" ref="25657490" role="outer"/>
<member type="way" ref="209124836" role="outer"/>
<member type="way" ref="119880388" role="outer"/>
<member type="way" ref="119880389" role="outer"/>
<member type="way" ref="119983752" role="outer"/>
<member type="way" ref="136380499" role="outer"/>
<member type="way" ref="120024176" role="outer"/>
<member type="way" ref="209124834" role="outer"/>
<member type="way" ref="77909008" role="outer"/>
In order to get all buildings inside that boundary using the method described here, I need to convert these ways to an ordered list of points such that every point is connected to its successor.
Example 1
I have way 119880388, whose last point is 132.100403,43.3959161, hence, it must be followed by a way, which starts there (way 209124836 in this case).
119880388;132.1469949,43.504065|132.1439962,43.4906939|132.1400282,43.4747441|132.1402881,43.4739524|132.1397559,43.4733796|132.139471,43.4710427|132.1324332,43.4650797|132.1321001,43.4625553|132.1273123,43.4602785|132.1268996,43.4611024|132.1262186,43.4615517|132.1250473,43.4606504|132.1253362,43.4590926|132.1199706,43.4567557|132.1181958,43.4534|132.1165449,43.4536997|132.1151003,43.4558569|132.1122111,43.4550479|132.1120048,43.4568456|132.1106349,43.456653|132.1074084,43.4565518|132.1045214,43.4568074|132.1018878,43.457799|132.1045918,43.45418|132.1045214,43.4533315|132.1049016,43.4526109|132.0974329,43.4515698|132.0970943,43.4510349|132.0962379,43.4508758|132.0956005,43.4499071|132.0965565,43.4495456|132.100208,43.4491561|132.096659,43.4434507|132.098349,43.4423872|132.0988278,43.440833|132.0981518,43.4397695|132.099194,43.4388083|132.0939234,43.4347791|132.0934023,43.4339098|132.0915574,43.4311281|132.0898252,43.4291849|132.0888394,43.4281416|132.0866256,43.4271254|132.0844248,43.4271615|132.0837273,43.4275697|132.0837273,43.4262298|132.0852483,43.4242149|132.0850934,43.4232227|132.0822767,43.4233557|132.0820373,43.4226294|132.0811501,43.4219032|132.083854,43.4190391|132.0911773,43.4176683|132.0920223,43.4173205|132.0863045,43.4153769|132.0873467,43.4135355|132.0895155,43.4113666|132.0937405,43.4059441|132.0943038,43.4036522|132.0952051,43.4011965|132.0967132,43.3988428|132.0991074,43.3975125|132.100403,43.3959161|
209124836;132.100403,43.3959161|132.0973611,43.3915157|132.0945444,43.3876676|132.0947698,43.3862962|132.0962344,43.3844129|132.0891928,43.3825706|132.0861226,43.3815675|132.0843482,43.3835532|132.0826018,43.3824273|132.0823202,43.381158|132.0812181,43.3793895|132.0799157,43.3777247|132.0783487,43.3754872|132.0775037,43.3725185|132.076884,43.3713105|132.0734759,43.3689559|132.0715324,43.3696725|132.0686313,43.3693654|132.0671666,43.3700206|132.0670821,43.3692425|132.0649696,43.3681778|132.0646316,43.3658435|132.0619981,43.3665295|132.0613643,43.3651985|132.0623502,43.3648913|132.0608851,43.3614618|132.0596304,43.360689|132.0584397,43.359838|132.0568436,43.3605808|132.0524573,43.3620336|132.0516256,43.3627178|132.0467659,43.3583303|132.0505899,43.3557236|132.0502911,43.3542031|132.0457676,43.3518866|132.0457395,43.350668|132.0445706,43.3502788|132.0457676,43.3470836|132.0464436,43.3469607|132.0466971,43.3455064|132.046345,43.3446358|132.0472089,43.342042|132.0438833,43.3408081|132.043113,43.3408202|132.0429138,43.3413996|132.0405483,43.3413749|132.0393135,43.3412952|132.0381384,43.3409041|132.0377749,43.3393052|132.0369876,43.3385224|132.0374383,43.3363304|132.0392269,43.3357363|132.0392019,43.3313722|
Example 2
There are ways 25657490 and 77909008, which both end in point 132.0638277,43.3156504. Hence the correct order is 25657490, 77909008' where 77909008' is the inverted list of points of way 77909008 (132.0638277,43.3156504; 132.0641092,43.3159; ...).
25657490;132.0392019,43.3313722|132.0440197,43.3311274|132.0473289,43.3308512|132.0508932,43.3302733|132.0528244,43.3296177|132.0532452,43.3290625|132.0534252,43.3291183|132.0536528,43.3295151|132.0540176,43.3294683|132.0547127,43.3293056|132.0556996,43.3292972|132.0561718,43.3297738|132.0578026,43.3296177|132.0592617,43.3291807|132.0595621,43.3283378|132.0597767,43.327651|132.0608925,43.3269642|132.061665,43.3273076|132.0623516,43.3275573|132.0628666,43.3273388|132.0628666,43.3264023|132.063442,43.3254975|132.063507,43.3251849|132.0634183,43.3248517|132.0633476,43.3245859|132.0636823,43.3243424|132.0639065,43.3243493|132.0640514,43.3245921|132.0643604,43.3245921|132.0643422,43.3244722|132.0645664,43.3243798|132.065056,43.3230585|132.0654247,43.322644|132.065562,43.3219696|132.0655105,43.3216699|132.0657594,43.3212203|132.0653989,43.3213951|132.0650127,43.3217448|132.0648496,43.3223005|132.0648239,43.3225503|132.064223,43.3218947|132.0638111,43.3208893|132.0635333,43.3200936|132.0635103,43.3191278|132.0638536,43.3185658|132.0647549,43.3177852|132.0635103,43.315943|132.0638277,43.3156504|
77909008;132.1112088,43.3053453|132.1109191,43.305439|132.1103183,43.3058684|132.1100501,43.3059386|132.1093419,43.3059308|132.1090415,43.305962|132.1088377,43.3061182|132.10843,43.3068755|132.1073678,43.3069848|132.1070567,43.3069302|132.1067563,43.3067662|132.106134,43.3064617|132.1052113,43.3061963|132.1050397,43.306165|132.1042136,43.3064695|132.1039132,43.3070238|132.1035055,43.3071722|132.1032372,43.3073439|132.1030763,43.3075704|132.1030012,43.3078358|132.1030012,43.308312|132.1027223,43.3084682|132.1024004,43.3085853|132.1019927,43.3086399|132.1014992,43.308679|132.1011237,43.3088351|132.1002761,43.3091708|132.0999757,43.3092333|132.0997611,43.3094753|132.0996967,43.3096704|132.0989886,43.3104043|132.0984736,43.3104589|132.0975939,43.31074|132.0971647,43.310982|132.0966712,43.3111225|132.0953623,43.311185|132.09474,43.3111225|132.0941177,43.311021|132.0936886,43.311021|132.0932594,43.3111147|132.0930556,43.3112474|132.092959,43.3114192|132.0929054,43.3116143|132.0927337,43.3117549|132.0923475,43.311872|132.0918754,43.3122076|132.0917467,43.3122935|132.091339,43.312395|132.0909313,43.312395|132.0907274,43.3124262|132.0904485,43.3124184|132.0902983,43.3124262|132.0899764,43.3123638|132.089912,43.3124418|132.089397,43.3125902|132.0891181,43.312598|132.088528,43.3124965|132.08841,43.3125121|132.0878521,43.3127229|132.0876053,43.3127385|132.0872942,43.3126916|132.0869831,43.3127229|132.0861677,43.3130273|132.0860496,43.3132147|132.0857278,43.3133474|132.0855561,43.3133318|132.0851055,43.3135113|132.0848158,43.3137377|132.0844403,43.3138626|132.083818,43.3142061|132.0836786,43.3143388|132.0836035,43.3145418|132.0836464,43.3146589|132.0834211,43.3148228|132.0833996,43.3149945|132.0830027,43.3151585|132.0828095,43.315338|132.0824555,43.3153458|132.0820907,43.3152209|132.0817903,43.3152756|132.0810286,43.3153146|132.0808354,43.315377|132.0805994,43.3155566|132.0804921,43.31558|132.0803741,43.3155644|132.0802883,43.3155019|132.0801917,43.3153146|132.0801059,43.3152443|132.0799664,43.3152131|132.0797733,43.3152365|132.0796231,43.3152834|132.0794192,43.3154239|132.0792583,43.3154629|132.0791295,43.3154629|132.0790115,43.3154083|132.078797,43.3149243|132.0786575,43.3148618|132.0785073,43.314893|132.0784,43.3149555|132.0781103,43.3150179|132.0777455,43.3151428|132.0774344,43.3153146|132.0771018,43.3155253|132.076619,43.3156893|132.0762328,43.3159078|132.0757607,43.3160093|132.0751277,43.3160562|132.0745161,43.316142|132.0739261,43.3163996|132.0717588,43.31711|132.0699349,43.3178203|132.0687011,43.3184448|132.0679286,43.3187726|132.0674244,43.3189053|132.0670596,43.3189522|132.0666412,43.3189522|132.0663408,43.3188585|132.0661369,43.3186868|132.0660511,43.3184838|132.0660082,43.3182106|132.0658043,43.3178359|132.0650748,43.3172427|132.0641092,43.3159|132.0638277,43.3156504|
Are there any ready-made routines (ideally in Java), which do that (append points of ways to each other, inverting them where necessary).
Best Answer
The easiest way to get around with OSM polygon relations is to use OSM tools:
Tools -> Join linesEDIT
I have explained a more GIS-like way here: How to visually sort the order of Points with QGIS, GDAL, ...?