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Trying to detect cycle in graph using BFS but some test cases not passing

The first function isCycle is getting parameters from driver code of website. I have worked for more than 2 hours in order to debug why its not working in my logic. Anything i need to improve here.
This is the link of question.
https://practice.geeksforgeeks.org/problems/detect-cycle-in-an-undirected-graph/1/#
public boolean isCycle(int V, ArrayList<ArrayList<Integer>> adj) {
if(V<=2){
return false;
}
Map<Integer, ArrayList<Integer> > graph = new TreeMap<>();
for(int i = 0; i<V; i++){
graph.put(i,adj.get(i) );
}
return detectCycle(graph);
}
static boolean detectCycle(Map<Integer, ArrayList<Integer> > graph){
Map<Integer, Integer> parentChild = new TreeMap<>();
Map<Integer, Boolean> isVisited = new TreeMap<>();
Queue<Integer> q = new LinkedList<>();
q.add(0);
isVisited.put(0,true);
parentChild.put(0,-1);
while(!q.isEmpty() ){
int curNode = q.remove();
if(graph.get(curNode) == null){
q.add(++curNode);
continue;
}
ArrayList<Integer> curElements = graph.get(curNode);
if(!isVisited.containsKey(curNode)){
q.add(curNode);
isVisited.put(0,true);
parentChild.put(0,0);
}
for(int temp: curElements){
if(!isVisited.containsKey(temp)){
isVisited.put(temp, true);
parentChild.put(temp,curNode);
q.add(temp);
}
else{
if((parentChild.get(temp) != curNode) && (isVisited.get(temp) == true)){
return true;
}
}
}
}
return false;
}
In this test case it failed. Short testcases are passing actually.
1805 829
1 321
1 499
1 694
1 1360
2 115
2 881
3 1592
4 846
5 1085
6 1654
7 691
7 872
7 1172
7 1243
7 1721
9 844
9 984
12 724
13 353
13 895
13 1107
15 1514
20 1679
22 329
22 759
23 124
23 1003
24 1239
30 1032
31 1004
31 1342
31 1641
33 466
34 393
35 518
38 1666
39 831
40 362
41 1615
42 1006
43 886
45 428
46 1084
47 178
48 1177
49 1564
51 1283
52 1042
54 593
55 1456
57 1460
58 806
64 521
64 741
65 86
65 1325
66 759
66 1773
67 704
67 769
67 1541
69 244
70 896
70 1470
72 263
72 1460
73 1013
74 465
74 496
75 733
77 218
77 436
77 1105
79 1664
82 221
82 577
82 714
84 485
84 1768
85 1313
87 166
88 510
88 1266
90 139
92 679
92 1196
93 441
93 1157
94 1417
96 441
96 1716
97 768
97 1578
100 1047
102 1508
105 724
106 1356
106 1756
110 801
114 862
114 1188
115 892
115 1787
116 782
117 1178
118 572
118 1593
120 1156
121 128
123 494
127 456
127 1591
129 659
131 444
133 1352
134 146
134 1319
135 1049
136 735
137 349
137 1799
138 1042
139 375
139 887
140 170
142 453
142 1703
143 911
144 976
145 1415
146 1548
148 1581
149 396
149 546
149 1602
150 1548
150 1703
151 828
151 1404
153 406
158 513
160 187
161 292
164 1009
164 1465
165 786
166 817
168 1493
169 1320
170 211
170 615
174 1798
175 1300
176 1079
177 599
177 715
177 747
178 999
179 691
179 869
179 870
180 883
181 1318
183 233
186 1323
188 837
188 1089
189 720
189 1799
192 891
192 1514
195 913
198 1604
199 926
201 1004
201 1239
203 1109
204 841
204 1088
206 1110
207 1523
209 584
209 1649
210 738
211 773
212 915
212 1060
214 623
214 1313
215 318
215 1082
217 303
218 241
221 1247
223 1740
225 1351
226 353
229 1298
232 1558
233 1287
234 1309
236 624
238 1539
239 911
241 1145
242 787
243 991
244 1234
245 1195
246 657
246 1113
247 1339
248 342
249 454
252 1781
253 619
254 1354
254 1531
255 1508
258 1617
261 419
261 1728
262 530
262 1678
263 562
263 984
263 1288
263 1631
263 1683
265 738
265 982
265 1454
266 1613
271 828
276 1486
279 1719
280 549
280 1259
283 1722
284 1117
289 1301
290 419
291 494
291 1180
291 1738
292 527
294 686
294 1667
294 1702
294 1752
296 1318
300 1597
303 356
305 425
305 1071
305 1726
306 780
307 1098
307 1236
308 469
308 662
311 1520
313 1386
315 1374
323 888
326 1062
330 839
330 1586
336 415
337 645
338 1606
340 1443
341 1572
343 1380
344 569
344 1062
345 1227
346 1026
346 1066
347 1685
348 1404
349 1470
351 407
353 780
355 748
357 1532
358 1610
359 551
359 1674
360 1013
361 1443
362 726
362 768
362 1430
366 509
366 1617
370 1318
370 1334
377 1582
378 933
380 556
383 1553
385 470
385 1493
389 986
389 1738
390 1071
391 1268
392 941
393 1793
394 1504
394 1537
398 1022
398 1089
399 1540
400 1124
400 1619
401 1086
404 1585
410 491
410 561
410 856
413 1651
417 1260
418 1425
418 1723
420 1595
421 1063
423 559
423 1383
424 1572
425 861
425 1775
427 1584
428 1672
432 708
435 783
435 1037
435 1576
436 856
436 1022
437 1731
442 635
443 835
444 629
445 1135
446 743
446 836
448 918
450 1582
454 1136
455 767
458 1769
459 928
459 1448
462 1745
463 1161
466 789
466 1144
468 1799
470 971
472 565
472 709
472 810
474 542
474 854
477 654
479 848
482 1385
484 642
485 1207
489 1476
489 1788
490 1569
494 1087
495 617
498 1594
500 571
501 1747
506 720
506 1069
507 912
507 962
508 921
508 1343
509 1143
511 1291
514 1557
515 849
517 554
518 1141
520 1022
520 1354
520 1607
522 907
523 902
527 972
527 1170
527 1254
528 1051
531 606
531 860
535 1177
536 957
539 913
541 698
541 1213
543 1782
544 1242
544 1429
544 1575
547 789
548 1086
550 560
554 1759
555 801
557 1706
559 1551
561 1163
569 1167
571 859
571 1336
572 1135
573 1704
576 990
579 847
579 1684
580 1153
580 1794
581 1123
581 1201
582 1226
586 1315
588 1135
589 1414
594 1084
594 1284
595 1766
598 1650
602 1715
604 1168
605 1337
607 1429
610 816
610 1263
616 1435
619 1281
620 1180
624 704
625 860
625 1242
626 959
626 1171
627 1425
629 1382
630 878
630 1211
631 1494
633 916
638 927
638 975
638 1773
639 842
640 695
640 787
642 802
644 1333
645 900
650 890
653 1724
654 890
654 1214
655 1226
655 1712
657 1388
658 1208
659 840
659 1519
663 892
664 1523
668 1336
672 1062
675 745
677 1561
678 1060
680 1255
681 1475
681 1655
682 708
682 781
683 1486
687 1609
690 1618
690 1679
691 903
693 1084
695 719
696 1310
696 1357
699 908
705 758
714 1745
718 782
718 978
719 1682
723 978
723 1762
724 1454
731 1017
732 1393
736 1730
739 1764
740 1674
742 1618
748 1068
748 1071
748 1202
748 1569
749 853
749 1427
751 1625
754 1506
755 1615
757 1663
759 1132
760 789
760 1024
760 1575
760 1771
764 819
766 1021
766 1369
767 1424
770 1751
773 1363
773 1402
775 1372
777 1515
779 1519
780 1702
781 1170
782 1137
782 1353
785 1058
786 983
786 1080
787 1721
789 929
792 1392
792 1784
793 1246
795 1782
799 937
801 959
804 1480
805 1776
809 941
812 1275
813 1554
814 1388
817 904
817 1290
817 1345
818 1044
819 1014
820 1346
821 1607
822 1093
831 1209
835 1555
836 1138
844 1004
846 1223
852 974
852 1177
853 1121
858 870
860 1079
863 1261
867 1442
873 1763
876 1704
877 1301
877 1501
877 1643
883 1342
884 1745
889 1723
890 1376
894 1016
896 1132
896 1340
901 1628
903 1586
906 1388
910 1057
910 1082
912 1206
912 1413
912 1536
917 1670
918 1295
919 1105
925 1110
926 1716
927 1442
928 1335
931 1751
934 1337
939 1573
941 1559
948 1646
950 1314
951 1504
953 1675
954 1563
955 1522
955 1648
956 1229
956 1309
960 1232
962 1406
962 1672
964 998
964 1420
965 1661
967 1650
969 1771
972 1494
972 1744
973 1544
975 1464
977 1055
977 1226
978 1377
978 1790
979 1326
979 1545
980 1450
981 1157
982 1605
983 1130
986 1292
986 1769
987 1692
990 1788
994 1460
1000 1337
1003 1549
1008 1528
1009 1277
1009 1465
1013 1301
1013 1512
1013 1671
1014 1094
1017 1572
1025 1507
1025 1666
1032 1613
1033 1590
1035 1213
1037 1304
1039 1139
1040 1349
1044 1460
1046 1497
1058 1601
1067 1178
1067 1403
1069 1724
1070 1722
1071 1299
1072 1299
1073 1132
1079 1602
1081 1281
1082 1211
1088 1359
1091 1171
1092 1745
1107 1441
1109 1248
1109 1524
1109 1574
1113 1157
1116 1611
1116 1671
1117 1194
1119 1340
1120 1507
1120 1511
1124 1238
1127 1152
1127 1450
1129 1722
1133 1409
1133 1707
1135 1242
1135 1530
1137 1503
1139 1672
1142 1716
1143 1219
1144 1246
1149 1654
1153 1599
1156 1533
1157 1584
1174 1197
1174 1676
1175 1555
1176 1396
1176 1797
1182 1476
1185 1736
1192 1589
1198 1791
1199 1732
1206 1561
1206 1765
1218 1242
1219 1695
1220 1722
1223 1314
1224 1484
1235 1245
1237 1547
1239 1727
1239 1769
1251 1431
1251 1453
1253 1459
1255 1415
1255 1474
1255 1785
1256 1794
1258 1365
1260 1700
1265 1535
1271 1441
1281 1544
1291 1732
1302 1379
1308 1326
1308 1773
1313 1431
1318 1414
1323 1657
1324 1730
1333 1597
1337 1411
1337 1804
1343 1575
1345 1508
1353 1753
1356 1711
1358 1750
1359 1523
1361 1796
1368 1539
1369 1514
1378 1400
1382 1755
1383 1550
1389 1464
1391 1520
1398 1702
1399 1550
1404 1507
1410 1778
1412 1764
1417 1441
1421 1608
1422 1439
1427 1511
1431 1610
1438 1509
1441 1461
1442 1506
1445 1626
1445 1649
1446 1507
1446 1622
1450 1660
1453 1756
1459 1603
1462 1546
1463 1646
1463 1755
1475 1799
1478 1595
1484 1629
1488 1702
1493 1762
1494 1656
1497 1629
1497 1804
1520 1724
1523 1666
1528 1790
1529 1681
1530 1614
1533 1735
1549 1621
1550 1589
1553 1672
1556 1688
1569 1698
1570 1621
1570 1747
1582 1629
1584 1622
1600 1657
1611 1699
1621 1768
1632 1794
1634 1648
1640 1644
1653 1792
1656 1765
1671 1672
1684 1735
1686 1783
1711 1803
1728 1756
1738 1777
1761 1766
1772 1780

Well, assuming our goal is not to find optimal solution, but to solve problem using BFS...
Next code snippet:
Queue<Integer> q = new LinkedList<>();
q.add(0);
isVisited.put(0,true);
parentChild.put(0,-1);
suffers from the following issue: in case of BFS we need to traverse graph in very specific order, basically we need to find some concept of level and always traverse from one level to another. Think why you code fails following simple test cases (yep, both geeksforgeeks and hackerrank failed to provide reliable test cases):
4, {{}, {2,3}, {1,3}, {1,2}} - returns false, expected true
4, {{3}, {3}, {3}, {0,1,2}} - returns true, expected false
One BFS idea: if our graph has a cycle, disconnecting leaf nodes (removing corresponding edges and splitting single graph into two) does not affect that cycle, so if we iteratively disconnected all leaf nodes (that is our level) and our graph still has edges that means we got a cycle.
public static boolean isCycle(int V, List<List<Integer>> adj) {
// queue contains leaf nodes only
Set<Integer> queue = new HashSet<>();
List<Set<Integer>> graph = new ArrayList<>();
// preparing input data
for (int node = 0; node < V; node++) {
List<Integer> input = adj.get(node);
Set<Integer> neighbours = input != null ? new HashSet<>(input) : new HashSet<>();
neighbours.remove(node);
graph.add(node, neighbours);
if (neighbours.size() == 1) {
// leaf node found, adding to queue
queue.add(node);
}
}
while (!queue.isEmpty()) {
// next BFS level
Set<Integer> level = new HashSet<>();
for (int node : queue) {
for (int neighbour : graph.get(node)) {
// removing edge neighbour->node
Set<Integer> next = graph.get(neighbour);
next.remove(node);
if (next.size() == 1) {
// got another one leaf node among neighbours
level.add(neighbour);
}
}
// removing edges node->neighbours
graph.set(node, new HashSet<>());
}
queue = level;
}
return graph.stream().anyMatch(set -> set.size() > 0);
}
However, if your BFS idea was to traverse the single graph level by level, the code could be (I see no difference with DFS though):
public static boolean isCycle(int V, List<List<Integer>> adj) {
boolean[] seen = new boolean[V];
for (int i = 0; i < V; i++) {
if (seen[i]) {
continue;
}
Deque<int[]> q = new LinkedList<>();
// storing (node, parent)
q.add(new int[]{i, -1});
seen[i] = true;
while (!q.isEmpty()) {
int[] node = q.poll();
for (int next : adj.get(node[0])) {
// seen node on the previous level
if (next == node[1]) {
continue;
}
if (seen[next]) {
return true;
}
q.add(new int[]{next, node[0]});
seen[next] = true;
}
}
}
return false;
}

double precision no truncation when typecast to int

The following:
double x = .43;
BigDecimal bd = new BigDecimal(z);
System.out.println(bd);
outputs:
.4299999.....
why does
double u = z*100;
bd = new BigDecimal(u);
System.out.println(u);
output:
43?
more generally I'm trying to find a case where the double representation causes a truncation problem. Consider the following:
double d;
int j;
BigDecimal bd;
for(int i = 0; i<10000;i++){
d= (double)(i/100.);
j = (int)(d*100.);
bd = new BigDecimal(j);
System.out.println(bd);
}
In not a single case is truncating occurring

In not a single case is truncating occurring
That is incorrect. Truncation occurs many times, you just didn't look close enough.
E.g. for i = 29:
int i = 29;
double d= i / 100.;
int j = (int)(d * 100.);
BigDecimal bd = new BigDecimal(j);
System.out.println(bd);
Output
28
OOPS!!!
Though I don't know what the point of converting j to bd is, since new BigDecimal(int) is always exact.
If you want to see all the truncation errors, try this:
for (int i = 0; i < 10000; i++){
double d = i / 100.;
int j = (int)(d * 100.);
if (i != j)
System.out.println(i + ": " + j);
}
Output
29: 28
57: 56
58: 57
113: 112
114: 113
115: 114
116: 115
201: 200
203: 202
205: 204
207: 206
226: 225
228: 227
230: 229
232: 231
251: 250
253: 252
255: 254
402: 401
406: 405
410: 409
414: 413
427: 426
431: 430
435: 434
439: 438
452: 451
456: 455
460: 459
464: 463
477: 476
481: 480
485: 484
489: 488
502: 501
506: 505
510: 509
803: 802
804: 803
812: 811
820: 819
828: 827
829: 828
837: 836
845: 844
853: 852
854: 853
862: 861
870: 869
878: 877
879: 878
887: 886
895: 894
903: 902
904: 903
912: 911
920: 919
928: 927
929: 928
937: 936
945: 944
953: 952
954: 953
962: 961
970: 969
978: 977
979: 978
987: 986
995: 994
1003: 1002
1004: 1003
1012: 1011
1020: 1019
1606: 1605
1608: 1607
1615: 1614
1624: 1623
1631: 1630
1633: 1632
1640: 1639
1649: 1648
1656: 1655
1658: 1657
1665: 1664
1674: 1673
1681: 1680
1683: 1682
1690: 1689
1699: 1698
1706: 1705
1708: 1707
1715: 1714
1724: 1723
1731: 1730
1733: 1732
1740: 1739
1749: 1748
1756: 1755
1758: 1757
1765: 1764
1774: 1773
1781: 1780
1783: 1782
1790: 1789
1799: 1798
1806: 1805
1808: 1807
1815: 1814
1824: 1823
1831: 1830
1833: 1832
1840: 1839
1849: 1848
1856: 1855
1858: 1857
1865: 1864
1874: 1873
1881: 1880
1883: 1882
1890: 1889
1899: 1898
1906: 1905
1908: 1907
1915: 1914
1924: 1923
1931: 1930
1933: 1932
1940: 1939
1949: 1948
1956: 1955
1958: 1957
1965: 1964
1974: 1973
1981: 1980
1983: 1982
1990: 1989
1999: 1998
2006: 2005
2008: 2007
2015: 2014
2024: 2023
2031: 2030
2033: 2032
2040: 2039
3205: 3204
3212: 3211
3216: 3215
3223: 3222
3230: 3229
3237: 3236
3241: 3240
3248: 3247
3255: 3254
3262: 3261
3266: 3265
3273: 3272
3280: 3279
3287: 3286
3291: 3290
3298: 3297
3305: 3304
3312: 3311
3316: 3315
3323: 3322
3330: 3329
3337: 3336
3341: 3340
3348: 3347
3355: 3354
3362: 3361
3366: 3365
3373: 3372
3380: 3379
3387: 3386
3391: 3390
3398: 3397
3405: 3404
3412: 3411
3416: 3415
3423: 3422
3430: 3429
3437: 3436
3441: 3440
3448: 3447
3455: 3454
3462: 3461
3466: 3465
3473: 3472
3480: 3479
3487: 3486
3491: 3490
3498: 3497
3505: 3504
3512: 3511
3516: 3515
3523: 3522
3530: 3529
3537: 3536
3541: 3540
3548: 3547
3555: 3554
3562: 3561
3566: 3565
3573: 3572
3580: 3579
3587: 3586
3591: 3590
3598: 3597
3605: 3604
3612: 3611
3616: 3615
3623: 3622
3630: 3629
3637: 3636
3641: 3640
3648: 3647
3655: 3654
3662: 3661
3666: 3665
3673: 3672
3680: 3679
3687: 3686
3691: 3690
3698: 3697
3705: 3704
3712: 3711
3716: 3715
3723: 3722
3730: 3729
3737: 3736
3741: 3740
3748: 3747
3755: 3754
3762: 3761
3766: 3765
3773: 3772
3780: 3779
3787: 3786
3791: 3790
3798: 3797
3805: 3804
3812: 3811
3816: 3815
3823: 3822
3830: 3829
3837: 3836
3841: 3840
3848: 3847
3855: 3854
3862: 3861
3866: 3865
3873: 3872
3880: 3879
3887: 3886
3891: 3890
3898: 3897
3905: 3904
3912: 3911
3916: 3915
3923: 3922
3930: 3929
3937: 3936
3941: 3940
3948: 3947
3955: 3954
3962: 3961
3966: 3965
3973: 3972
3980: 3979
3987: 3986
3991: 3990
3998: 3997
4005: 4004
4012: 4011
4016: 4015
4023: 4022
4030: 4029
4037: 4036
4041: 4040
4048: 4047
4055: 4054
4062: 4061
4066: 4065
4073: 4072
4080: 4079
4087: 4086
4091: 4090
6407: 6406
6410: 6409
6421: 6420
6424: 6423
6432: 6431
6435: 6434
6446: 6445
6449: 6448
6457: 6456
6460: 6459
6471: 6470
6474: 6473
6482: 6481
6485: 6484
6496: 6495
6499: 6498
6507: 6506
6510: 6509
6521: 6520
6524: 6523
6532: 6531
6535: 6534
6546: 6545
6549: 6548
6557: 6556
6560: 6559
6571: 6570
6574: 6573
6582: 6581
6585: 6584
6596: 6595
6599: 6598
6607: 6606
6610: 6609
6621: 6620
6624: 6623
6632: 6631
6635: 6634
6646: 6645
6649: 6648
6657: 6656
6660: 6659
6671: 6670
6674: 6673
6682: 6681
6685: 6684
6696: 6695
6699: 6698
6707: 6706
6710: 6709
6721: 6720
6724: 6723
6732: 6731
6735: 6734
6746: 6745
6749: 6748
6757: 6756
6760: 6759
6771: 6770
6774: 6773
6782: 6781
6785: 6784
6796: 6795
6799: 6798
6807: 6806
6810: 6809
6821: 6820
6824: 6823
6832: 6831
6835: 6834
6846: 6845
6849: 6848
6857: 6856
6860: 6859
6871: 6870
6874: 6873
6882: 6881
6885: 6884
6896: 6895
6899: 6898
6907: 6906
6910: 6909
6921: 6920
6924: 6923
6932: 6931
6935: 6934
6946: 6945
6949: 6948
6957: 6956
6960: 6959
6971: 6970
6974: 6973
6982: 6981
6985: 6984
6996: 6995
6999: 6998
7007: 7006
7010: 7009
7021: 7020
7024: 7023
7032: 7031
7035: 7034
7046: 7045
7049: 7048
7057: 7056
7060: 7059
7071: 7070
7074: 7073
7082: 7081
7085: 7084
7096: 7095
7099: 7098
7107: 7106
7110: 7109
7121: 7120
7124: 7123
7132: 7131
7135: 7134
7146: 7145
7149: 7148
7157: 7156
7160: 7159
7171: 7170
7174: 7173
7182: 7181
7185: 7184
7196: 7195
7199: 7198
7207: 7206
7210: 7209
7221: 7220
7224: 7223
7232: 7231
7235: 7234
7246: 7245
7249: 7248
7257: 7256
7260: 7259
7271: 7270
7274: 7273
7282: 7281
7285: 7284
7296: 7295
7299: 7298
7307: 7306
7310: 7309
7321: 7320
7324: 7323
7332: 7331
7335: 7334
7346: 7345
7349: 7348
7357: 7356
7360: 7359
7371: 7370
7374: 7373
7382: 7381
7385: 7384
7396: 7395
7399: 7398
7407: 7406
7410: 7409
7421: 7420
7424: 7423
7432: 7431
7435: 7434
7446: 7445
7449: 7448
7457: 7456
7460: 7459
7471: 7470
7474: 7473
7482: 7481
7485: 7484
7496: 7495
7499: 7498
7507: 7506
7510: 7509
7521: 7520
7524: 7523
7532: 7531
7535: 7534
7546: 7545
7549: 7548
7557: 7556
7560: 7559
7571: 7570
7574: 7573
7582: 7581
7585: 7584
7596: 7595
7599: 7598
7607: 7606
7610: 7609
7621: 7620
7624: 7623
7632: 7631
7635: 7634
7646: 7645
7649: 7648
7657: 7656
7660: 7659
7671: 7670
7674: 7673
7682: 7681
7685: 7684
7696: 7695
7699: 7698
7707: 7706
7710: 7709
7721: 7720
7724: 7723
7732: 7731
7735: 7734
7746: 7745
7749: 7748
7757: 7756
7760: 7759
7771: 7770
7774: 7773
7782: 7781
7785: 7784
7796: 7795
7799: 7798
7807: 7806
7810: 7809
7821: 7820
7824: 7823
7832: 7831
7835: 7834
7846: 7845
7849: 7848
7857: 7856
7860: 7859
7871: 7870
7874: 7873
7882: 7881
7885: 7884
7896: 7895
7899: 7898
7907: 7906
7910: 7909
7921: 7920
7924: 7923
7932: 7931
7935: 7934
7946: 7945
7949: 7948
7957: 7956
7960: 7959
7971: 7970
7974: 7973
7982: 7981
7985: 7984
7996: 7995
7999: 7998
8007: 8006
8010: 8009
8021: 8020
8024: 8023
8032: 8031
8035: 8034
8046: 8045
8049: 8048
8057: 8056
8060: 8059
8071: 8070
8074: 8073
8082: 8081
8085: 8084
8096: 8095
8099: 8098
8107: 8106
8110: 8109
8121: 8120
8124: 8123
8132: 8131
8135: 8134
8146: 8145
8149: 8148
8157: 8156
8160: 8159
8171: 8170
8174: 8173
8182: 8181
8185: 8184
That is 573 times, i.e. 5.73% of the time.

Where is the Chinese character "𩄀" in a java .class file

I have such a java class:
public class UnicodeTest {
public static void main(String[] args) {
String s = "中";
String s1 = "𩄀";
System.out.println(s.length());
System.out.println(s1.length());
System.out.println(s1.toCharArray().length);
}
}
then I use xxd to see the compiled class file:
0000000: cafe babe 0000 0032 0031 0700 0201 000b .......2.1......
0000010: 556e 6963 6f64 6554 6573 7407 0004 0100 UnicodeTest.....
0000020: 106a 6176 612f 6c61 6e67 2f4f 626a 6563 .java/lang/Objec
0000030: 7401 0006 3c69 6e69 743e 0100 0328 2956 t...<init>...()V
0000040: 0100 0443 6f64 650a 0003 0009 0c00 0500 ...Code.........
0000050: 0601 000f 4c69 6e65 4e75 6d62 6572 5461 ....LineNumberTa
0000060: 626c 6501 0012 4c6f 6361 6c56 6172 6961 ble...LocalVaria
0000070: 626c 6554 6162 6c65 0100 0474 6869 7301 bleTable...this.
0000080: 000d 4c55 6e69 636f 6465 5465 7374 3b01 ..LUnicodeTest;.
0000090: 0004 6d61 696e 0100 1628 5b4c 6a61 7661 ..main...([Ljava
00000a0: 2f6c 616e 672f 5374 7269 6e67 3b29 5608 /lang/String;)V.
00000b0: 0011 0100 03e4 b8ad 0800 1301 0006 eda1 ................
00000c0: a4ed b480 0900 1500 1707 0016 0100 106a ...............j
00000d0: 6176 612f 6c61 6e67 2f53 7973 7465 6d0c ava/lang/System.
00000e0: 0018 0019 0100 036f 7574 0100 154c 6a61 .......out...Lja
00000f0: 7661 2f69 6f2f 5072 696e 7453 7472 6561 va/io/PrintStrea
0000100: 6d3b 0a00 1b00 1d07 001c 0100 106a 6176 m;...........jav
0000110: 612f 6c61 6e67 2f53 7472 696e 670c 001e a/lang/String...
0000120: 001f 0100 066c 656e 6774 6801 0003 2829 .....length...()
0000130: 490a 0021 0023 0700 2201 0013 6a61 7661 I..!.#.."...java
0000140: 2f69 6f2f 5072 696e 7453 7472 6561 6d0c /io/PrintStream.
0000150: 0024 0025 0100 0770 7269 6e74 6c6e 0100 .$.%...println..
0000160: 0428 4929 560a 001b 0027 0c00 2800 2901 .(I)V....'..(.).
0000170: 000b 746f 4368 6172 4172 7261 7901 0004 ..toCharArray...
0000180: 2829 5b43 0100 0461 7267 7301 0013 5b4c ()[C...args...[L
0000190: 6a61 7661 2f6c 616e 672f 5374 7269 6e67 java/lang/String
00001a0: 3b01 0001 7301 0012 4c6a 6176 612f 6c61 ;...s...Ljava/la
00001b0: 6e67 2f53 7472 696e 673b 0100 0273 3101 ng/String;...s1.
00001c0: 000a 536f 7572 6365 4669 6c65 0100 1055 ..SourceFile...U
00001d0: 6e69 636f 6465 5465 7374 2e6a 6176 6100 nicodeTest.java.
00001e0: 2100 0100 0300 0000 0000 0200 0100 0500 !...............
00001f0: 0600 0100 0700 0000 2f00 0100 0100 0000 ......../.......
0000200: 052a b700 08b1 0000 0002 000a 0000 0006 .*..............
0000210: 0001 0000 0002 000b 0000 000c 0001 0000 ................
0000220: 0005 000c 000d 0000 0009 000e 000f 0001 ................
0000230: 0007 0000 0078 0002 0003 0000 0026 1210 .....x.......&..
0000240: 4c12 124d b200 142b b600 1ab6 0020 b200 L..M...+..... ..
0000250: 142c b600 1ab6 0020 b200 142c b600 26be .,..... ...,..&.
0000260: b600 20b1 0000 0002 000a 0000 001a 0006 .. .............
0000270: 0000 0005 0003 0006 0006 0007 0010 0008 ................
0000280: 001a 0009 0025 000a 000b 0000 0020 0003 .....%....... ..
0000290: 0000 0026 002a 002b 0000 0003 0023 002c ...&.*.+.....#.,
00002a0: 002d 0001 0006 0020 002e 002d 0002 0001 .-..... ...-....
00002b0: 002f 0000 0002 0030 ./.....0
I have found the Chinese character "中" in line 12 03e4 b8ad, unicode U+4E2D, which in UTF-8 is E4 B8 AD, but I can't find another character "𩄀", unicode U+29100, which I expected something like "04 F0 A9 84 80", why?

Let's use javap.
Compile first with
javac UnicodeTest.java
Then disassemble with
javap -v UnicodeTest.class (truncated to relevant part) :
Constant pool:
#1 = Methodref #9.#18 // java/lang/Object."<init>":()V
#2 = String #19 // 中
#3 = String #20 // 𩄀
#4 = Fieldref #21.#22 //
... truncated
#17 = Utf8 UnicodeTest.java
#18 = NameAndType #10:#11 // "<init>":()V
#19 = Utf8 中
#20 = Utf8 𩄀
Item #20 in constant pool is what you are looking for.
Now, you let's check JVM class file format.
Utf8 datastructure is CONSTANT_Utf8_info
CONSTANT_Utf8_info {
u1 tag;
u2 length;
u1 bytes[length];
}
tag is CONSTANT_Utf8 (01). length is 00 06, bytes are ed a1 a4 ed b4 80
According to unicode lookup, mentioned character should have codepoint 0x29100.
Now back to JVM spec.
Characters with code points above U+FFFF (so-called supplementary
characters) are represented by separately encoding the two surrogate
code units of their UTF-16 representation. Each of the surrogate code
units is represented by three bytes. This means supplementary
characters are represented by six bytes, u, v, w, x, y, and z :
I will not paste content here because it's too long, but you can look it up as Table 4.12. under CONSTANT_Utf8_info info (link above)
So that's why it is 6 bytes long.
Now let's take the formula
0x10000 + ((v & 0x0f) << 16) + ((w & 0x3f) << 10) +
((y & 0x0f) << 6) + (z & 0x3f)
By substituting v, w ,y and z output is 168192(10) which is 0x29100, which is expected code point.

The classic technique you can use to find that out is changing the value by something else and check the hex-dump for the difference. This was already used in the eighties when you "hacked" save games for games to increase e.g. attributes of your role playing character, etc.
I changed the character by a and it seems that the character can be found at offset 0xBE-0xC3 and has the value ED A1 A4 ED B4 80. I would have to look up the specifics of this to be able to explain why the value differs from the one you expected but Java's original support for Unicode was limited to two bytes (that's what the char type is defined. Unicode-characters with a 3+ bytes or more need to be encoded in a particular way in the Bytecode to tell the ClassLoader that it needs to be treated in a different way.

Can not compile in IntelliJ

Hello I am getting this error that I can not seem to go away. I am using IntelliJ CE current release, I have done a few fresh installs of the IDE. Nonetheless, I always get this error.
Here is the project I was working on:
My sanity check didn't work.. .
Also even more interesting…
only on the first run, when I open up any Java Project, I get this error:
Error:Internal error: (java.lang.VerifyError) Uninitialized object exists on backward branch 90
Exception Details:
Location:
org/jetbrains/kotlin/jps/build/KotlinBuilder.createCompileEnvironment(Ljava/util/Map;Lorg/jetbrains/kotlin/incremental/components/LookupTracker;Lorg/jetbrains/jps/incremental/CompileContext;Lorg/jetbrains/kotlin/jps/build/KotlinBuilder$MessageCollectorAdapter;)Lorg/jetbrains/kotlin/compilerRunner/JpsCompilerEnvironment; #171: goto
Reason:
Error exists in the bytecode
Bytecode:
0x0000000: bb03 fe59 b703 ff3a 0619 063a 0719 0713
0x0000010: 02d7 2cb6 0403 5719 0713 0405 bb04 0759
0x0000020: 2b3a 083a 093a 0a3a 0b3a 0c19 083a 0dbb
0x0000030: 0409 5919 08b9 040a 0100 b804 10b7 0411
0x0000040: c002 893a 0e19 0db9 028c 0100 c000 b03a
0x0000050: 0f19 0fb9 00b9 0100 3a10 1910 b900 be01
0x0000060: 0099 004d 1910 b900 c201 003a 1119 0e19
0x0000070: 11c0 028e 3a12 3a13 1912 b902 9101 00c0
0x0000080: 00c4 b804 173a 1419 1319 1419 11c0 028e
0x0000090: 3a15 3a16 3a17 1915 b902 9401 003a 1819
0x00000a0: 1719 1619 18b9 041b 0300 57a7 ffaf 190e
0x00000b0: 0000 3a13 190c 190b 190a 1909 1913 b704
0x00000c0: 1eb6 0403 5719 0713 0420 bb04 2259 2c2b
0x00000d0: 2db7 0425 b604 0357 1907 b604 283a 052a
0x00000e0: b704 2c3a 0619 06c6 0010 1906 b904 3101
0x00000f0: 00b6 013c 9a00 1319 04b2 0216 1304 3301
0x0000100: 0701 b801 fa01 b0bb 0262 5919 0619 05b2
0x0000110: 002e b604 3719 04c0 01c7 bb04 3959 b704
0x0000120: 3ab7 043d b0
Stackmap Table:
full_frame(#90,{Object[#2],Object[#649],Object[#727],Object[#98],Object[#428],Top,Object[#1022],Object[#1022],Object[#649],Uninitialized[#28],Uninitialized[#28],Object[#1005],Object[#1022],Object[#649],Object[#649],Object[#176],Object[#187]},{})
same_frame_extended(#174)
full_frame(#247,{Object[#2],Object[#649],Object[#727],Object[#98],Object[#428],Object[#1102],Object[#1070],Object[#1022],Object[#649],Object[#1031],Object[#1031],Object[#1005],Object[#1022],Object[#649],Object[#649],Object[#176],Object[#187],Top,Top,Object[#649]},{})
same_frame(#263)
java.lang.VerifyError: Uninitialized object exists on backward branch 90
Exception Details:
Location:
org/jetbrains/kotlin/jps/build/KotlinBuilder.createCompileEnvironment(Ljava/util/Map;Lorg/jetbrains/kotlin/incremental/components/LookupTracker;Lorg/jetbrains/jps/incremental/CompileContext;Lorg/jetbrains/kotlin/jps/build/KotlinBuilder$MessageCollectorAdapter;)Lorg/jetbrains/kotlin/compilerRunner/JpsCompilerEnvironment; #171: goto
Reason:
Error exists in the bytecode
Bytecode:
0x0000000: bb03 fe59 b703 ff3a 0619 063a 0719 0713
0x0000010: 02d7 2cb6 0403 5719 0713 0405 bb04 0759
0x0000020: 2b3a 083a 093a 0a3a 0b3a 0c19 083a 0dbb
0x0000030: 0409 5919 08b9 040a 0100 b804 10b7 0411
0x0000040: c002 893a 0e19 0db9 028c 0100 c000 b03a
0x0000050: 0f19 0fb9 00b9 0100 3a10 1910 b900 be01
0x0000060: 0099 004d 1910 b900 c201 003a 1119 0e19
0x0000070: 11c0 028e 3a12 3a13 1912 b902 9101 00c0
0x0000080: 00c4 b804 173a 1419 1319 1419 11c0 028e
0x0000090: 3a15 3a16 3a17 1915 b902 9401 003a 1819
0x00000a0: 1719 1619 18b9 041b 0300 57a7 ffaf 190e
0x00000b0: 0000 3a13 190c 190b 190a 1909 1913 b704
0x00000c0: 1eb6 0403 5719 0713 0420 bb04 2259 2c2b
0x00000d0: 2db7 0425 b604 0357 1907 b604 283a 052a
0x00000e0: b704 2c3a 0619 06c6 0010 1906 b904 3101
0x00000f0: 00b6 013c 9a00 1319 04b2 0216 1304 3301
0x0000100: 0701 b801 fa01 b0bb 0262 5919 0619 05b2
0x0000110: 002e b604 3719 04c0 01c7 bb04 3959 b704
0x0000120: 3ab7 043d b0
Stackmap Table:
full_frame(#90,{Object[#2],Object[#649],Object[#727],Object[#98],Object[#428],Top,Object[#1022],Object[#1022],Object[#649],Uninitialized[#28],Uninitialized[#28],Object[#1005],Object[#1022],Object[#649],Object[#649],Object[#176],Object[#187]},{})
same_frame_extended(#174)
full_frame(#247,{Object[#2],Object[#649],Object[#727],Object[#98],Object[#428],Object[#1102],Object[#1070],Object[#1022],Object[#649],Object[#1031],Object[#1031],Object[#1005],Object[#1022],Object[#649],Object[#649],Object[#176],Object[#187],Top,Top,Object[#649]},{})
same_frame(#263)
at org.jetbrains.kotlin.jps.build.KotlinBuilderService.createModuleLevelBuilders(KotlinBuilderService.java:30)
at org.jetbrains.jps.incremental.BuilderRegistry.<init>(BuilderRegistry.java:54)
at org.jetbrains.jps.incremental.BuilderRegistry.<init>(BuilderRegistry.java:33)
at org.jetbrains.jps.incremental.BuilderRegistry$Holder.<clinit>(BuilderRegistry.java:36)
at org.jetbrains.jps.incremental.BuilderRegistry.getInstance(BuilderRegistry.java:43)
at org.jetbrains.jps.cmdline.BuildRunner.runBuild(BuildRunner.java:133)
at org.jetbrains.jps.cmdline.BuildSession.runBuild(BuildSession.java:295)
at org.jetbrains.jps.cmdline.BuildSession.run(BuildSession.java:125)
at org.jetbrains.jps.cmdline.BuildMain$MyMessageHandler.lambda$channelRead0$0(BuildMain.java:236)
at org.jetbrains.jps.cmdline.BuildMain$MyMessageHandler$$Lambda$4/386536307.run(Unknown Source)
at org.jetbrains.jps.service.impl.SharedThreadPoolImpl.lambda$executeOnPooledThread$0(SharedThreadPoolImpl.java:42)
at org.jetbrains.jps.service.impl.SharedThreadPoolImpl$$Lambda$2/670035812.run(Unknown Source)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
also here is the first error in text:
Error:Internal error: (java.lang.NoClassDefFoundError) Could not initialize class org.jetbrains.jps.incremental.BuilderRegistry$Holder
java.lang.NoClassDefFoundError: Could not initialize class org.jetbrains.jps.incremental.BuilderRegistry$Holder
at org.jetbrains.jps.incremental.BuilderRegistry.getInstance(BuilderRegistry.java:43)
at org.jetbrains.jps.cmdline.BuildRunner.runBuild(BuildRunner.java:133)
at org.jetbrains.jps.cmdline.BuildSession.runBuild(BuildSession.java:295)
at org.jetbrains.jps.cmdline.BuildSession.run(BuildSession.java:125)
at org.jetbrains.jps.cmdline.BuildMain$MyMessageHandler.lambda$channelRead0$0(BuildMain.java:236)
at org.jetbrains.jps.cmdline.BuildMain$MyMessageHandler$$Lambda$14/473199672.run(Unknown Source)
at org.jetbrains.jps.service.impl.SharedThreadPoolImpl.lambda$executeOnPooledThread$0(SharedThreadPoolImpl.java:42)
at org.jetbrains.jps.service.impl.SharedThreadPoolImpl$$Lambda$2/670035812.run(Unknown Source)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
P.S. HALP I don’t wanna use eclipse!!!

There is an open issue logged, but the problem is not easily reproducible. It may help to update the project SDK to the most recent version (like 1.8.0_152).
Kotlin plug-in can be disabled as a workaround if you are not using it.

That's a known JDK issue: JDK-8046233
Please, update your Java installation.

java.lang.VerifyError when convert docx to html using Apache POI

I have a problem when I convert docx to html string. I use APACHE POI
InputStream is = new FileInputStream(file);
XWPFDocument document = new XWPFDocument(is);
is.close();
// 2) Prepare Html options
XHTMLOptions options = XHTMLOptions.create();
// Extract image
// 3) Convert XWPFDocument to HTML
ByteArrayOutputStream out = new ByteArrayOutputStream();
XHTMLConverter.getInstance().convert(document, out, options);
re = out.toString();
out.close();
I use
org.apache.poi.xwpf.converter.core-1.0.4.jar and org.apache.poi.xwpf.converter.xhtml-1.0.4.jar
When I run my application and I get error in console.
SEVERE: java.lang.VerifyError: Bad type on operand stack
Exception Details:
Location:
cusc/cchc/util/OfficeReader.convertDocxToHtml()Ljava/lang/String; #105:
invokeinterface
Reason:
Type 'org/apache/poi/xwpf/converter/xhtml/XHTMLOptions' (current frame, stack[3]) is not assignable to 'org/apache/poi/xwpf/converter/core/Options'
Current Frame:
bci: #105
flags: { }
locals: { 'cusc/cchc/util/OfficeReader', 'java/lang/String', 'java/io/FileInputStream', 'org/apache/poi/xwpf/usermodel/XWPFDocument', 'org/apache/poi/xwpf/converter/xhtml/XHTMLOptions', 'java/io/ByteArrayOutputStream' }
stack: { 'org/apache/poi/xwpf/converter/core/IXWPFConverter', 'org/apache/poi/xwpf/usermodel/XWPFDocument', 'java/io/ByteArrayOutputStream', 'org/apache/poi/xwpf/converter/xhtml/XHTMLOptions' }
Bytecode:
0x0000000: 1212 4c2a b400 16c6 018d 2ab4 0016 b600
0x0000010: 1c99 0183 b800 59b6 005f 1400 6369 bb00
0x0000020: 6559 b800 6714 006d 6bb8 006f b700 73b6
0x0000030: 0076 8561 b800 7ab3 007e bb00 c659 2ab4
0x0000040: 0016 b700 c84d bb01 3e59 2cb7 0140 4e2c
0x0000050: b601 41b8 0144 3a04 bb01 4959 b701 4b3a
0x0000060: 05b8 014c 2d19 0519 04b9 0151 0400 1905
0x0000070: b601 574c 1905 b601 582b bb00 2d59 b201
0x0000080: 59b8 015e b700 31b2 007e b601 6113 0164
0x0000090: b601 61b6 0036 1212 b601 664c 1301 6ab8
0x00000a0: 016c 3a06 1906 2bb6 0172 3a07 b800 473a
0x00000b0: 0819 08b6 004d 3a09 1909 b600 51c0 0057
0x00000c0: 3a0a 190a 1280 b900 8202 00c0 0086 3a0b
0x00000d0: 190a b800 883a 0c19 0bb6 008e b600 923a
0x00000e0: 0d19 0c19 0d19 0bb6 0097 b900 9b01 0012
0x00000f0: a0b8 00a2 3a0e 190e 12aa 12ac b900 ae03
0x0000100: 0019 0e12 b412 b6b9 00ae 0300 190e 12b8
0x0000110: 12ba b900 ae03 0019 0e12 bc12 beb9 00ae
0x0000120: 0300 190e 12c0 12c2 b900 ae03 0019 0e12
0x0000130: c4b2 007e b900 ae03 00a7 0050 1907 04b6
0x0000140: 0176 1301 6413 017c b601 663a 0f19 0e13
0x0000150: 017e bb00 2d59 b200 7eb8 015e b700 3113
0x0000160: 0164 b601 6119 0fb6 0161 b600 36b9 00ae
0x0000170: 0300 2b19 0f13 017c 1301 64b6 0166 190e
0x0000180: b901 8001 00b6 0166 4c19 07b6 0181 9aff
0x0000190: aea7 0027 b200 2013 0121 b601 23a7 001b
0x00001a0: 4d2c b601 8412 12b0 4d2c b601 8912 12b0
0x00001b0: 4d2c b601 8c12 12b0 2bb0
Exception Handler Table:
bci [3, 413] => handler: 416
bci [3, 413] => handler: 424
bci [3, 413] => handler: 432
Stackmap Table:
full_frame(#316,{Object[#1],Object[#68],Object[#322],Object[#318],Object[#325],Object[#329],Object[#365],Object[#375],Object[#72],Object[#82],Object[#87],Object[#134],Object[#416],Object[#68],Object[#175]},{})
same_frame_extended(#393)
full_frame(#404,{Object[#1],Object[#68]},{})
same_locals_1_stack_item_frame(#416,Object[#389])
same_locals_1_stack_item_frame(#424,Object[#394])
same_locals_1_stack_item_frame(#432,Object[#397])
same_frame(#440)
I search the error in web and they say it is a problem about JDK. I use JDK 7. Help me to fix this error.
Thank all