byte 跟 short的转换？？

Question

怎么都没人阿？
 
这是一个简单的转换：这个程序仅仅是把2个short转换成4 byte
再转换回来
 可是，结果好像有点随机， 有对的 也有错的；
这是为何那》？？？？？
//******************
class TestChange
{
public static void main(String args[])
{

  short index[]=new short[2];
  byte buf[]=new byte[4]; 
            short codebuf[]=new short[2];  

for(int i=0;i<100;i++)
{
  index[0]=(short)(Math.random()*1000);
  index[1]=(short)(Math.random()*1000);



    System.out.print(index[0]+"\t"+index[1]+"\t");  
   
    buf[1]=(byte)(index[0]);
    buf[0]=(byte)(index[0]>>8);
    
    buf[3]=(byte)(index[1]);
    buf[2]=(byte)(index[1]>>8);
    
    //now to decode 
   
    codebuf[0]=(short)(buf[0]<<8);
    codebuf[0]=(short)((int)codebuf[0]+(int)buf[1] ) ;
     
    codebuf[1]=(short)(buf[2]<<8);
    codebuf[1]=(short)((int)codebuf[1]+(int)buf[3]);
  
  
    System.out.println("\t"+codebuf[0]+"\t"+codebuf[1]); 
     
   }//for
}
}
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287     865             287     865
37      743             37      487
499     104             243     104
752     263             496     263
342     103             342     103
949     978             693     722
350     118             350     118
843     273             843     273
688     490             432     234
616     920             616     664
720     69              464     69
594     157             594     -99
603     678             603     422
241     396             -15     140
358     40              358     40
228     747             -28     491
214     743             -42     487
819     41              819     41
942     791             686     791
880     665             880     409
313     964             313     708
871     571             871     571
792     735             792     479
296     50              296     50
49      792             49      792
209     418             -47     162
917     227             661     -29
549     595             549     595
967     348             711     348
259     664             259     408
960     670             704     414
399     901             143     645
66      49              66      49
677     406             421     150
859     129             859     -127
170     464             -86     208
827     214             827     -42
269     975             269     719
289     452             289     196
281     798             281     798
402     745             146     489
477     681             221     425
201     97              -55     97
804     511             804     255
397     232             141     -24
918     967             662     711
33      162             33      -94
678     342             422     342
949     76              693     76
743     155             487     -101
388     318             132     318
463     463             207     207
43      483             43      227
816     183             816     -73
274     632             274     632
756     571             500     571
242     421             -14     165
964     3               708     3
201     500             -55     244
657     560             401     560
291     890             291     890
814     530             814     530
705     155             449     -101
903     802             647     802
274     111             274     111
946     335             690     335
125     490             125     234
555     331             555     331
272     463             272     207
394     451             138     195
692     144             436     -112
369     462             369     206
708     283             452     283
734     991             478     735
242     97              -14     97
226     622             -30     622
830     869             830     869
262     465             262     209
132     231             -124    -25
249     441             -7      185
7       285             7       285
20      961             20      705
164     590             -92     590
492     381             236     381
797     813             797     813
678     602             422     602
588     303             588     303
320     437             320     181
967     158             711     -98
511     941             255     685
503     400             247     144
870     699             870     443
914     738             658     482
0       199             0       -57
214     987             -42     731
218     807             -38     807
168     678             -88     422
778     512             778     512
372     509             372     253
118     594             118     594
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