I solved this exercise of displaying a table of numbers from 1 to 256 in binary, octal and hexadecimal. I made this program to convert from decimal to binary and took that binary number to convert to octal and hexadecimal to made a table of binary, octal and hexadecimal. You might see that the way I found out which was the binary representation of the decimal number can be applied to the other bases and I didn't do it that way because I wanted to see if I could do it like this, I'll try to apply that method to the other basis now. Note: I overloaded the method binToBase () because I just learnt how to do it this week and seemed like the perfect oportunity to test it, haha.

is this good code? I'm pretty ashamed of how long it took for me to solve this ( 2 days )

public class Table {

public static final int BIN_BASE = 2 ;
public static final String HEX_BASE = "Hexa" ;
public static final int OCT_BASE = 8 ;

public static final int ROOF = 256 ;

public static void main ( String[] args ) {

int bin ;

for ( int i = 1 ; i <= ROOF ; i++ ){
bin = convertToBin ( i ) ;
System.out.printf ( "%10d\t" , bin ) ;
System.out.printf ( "%10s\t" , convertToBase ( bin , OCT_BASE ) ) ;
System.out.printf ( "%10s\n" , convertToBase ( bin, HEX_BASE ) ) ;
}

}

public static String convertToBase ( int convert , String base ) {

String hex = "" ;
int bin = convert ;

do {
switch ( bin % 10000 ) {

case 0 :
hex = '0' + hex ;
break ;
case 1 :
hex = '1' + hex ;
break ;
case 10 :
hex = '2' + hex ;
break ;
case 11 :
hex = '3' + hex ;
break ;
case 100 :
hex = '4' + hex ;
break ;
case 101 :
hex = '5' + hex ;
break ;
case 110 :
hex = '6' + hex ;
break ;
case 111 :
hex = '7' + hex ;
break ;
case 1000 :
hex = '8' + hex ;
break ;
case 1001 :
hex = '9' + hex ;
break ;
case 1010 :
hex = 'A' + hex ;
break ;
case 1011 :
hex = 'B' + hex ;
break ;
case 1100 :
hex = 'C' + hex ;
break ;
case 1101 :
hex = 'D' + hex ;
break ;
case 1110 :
hex = 'E' + hex ;
break ;
default :
hex = 'F' + hex ;
break ;

}

bin /= 10000 ;

} while ( bin > 0 ) ;

return hex ;
}

public static int convertToBase ( int convert , int base ){

int factor = 1 ;
int bin = convert ;
int oct = 0 ;

do {

switch ( bin % 1000 ) {

case 0 :
break ;
case 1 :
oct += factor * 1 ;
break ;
case 10 :
oct += factor * 2 ;
break ;
case 11 :
oct += factor * 3 ;
break ;
case 100 :
oct += factor * 4 ;
break ;
case 101 :
oct += factor * 5 ;
break ;
case 110 :
oct += factor * 6 ;
break ;
default :
oct += factor * 7 ;
break ;

}

bin /= 1000 ;

factor *= 10 ;

} while ( bin > 0 ) ;

return oct ;

}

public static int convertToBin ( int original ) {

int bin = 0 ;
int sum = 0 ;
int exponent = 0 ;

while ( sum < original ){

sum += Math.pow ( 2 , exponent ) ;
exponent ++ ;
bin *= 10 ;
bin ++ ;

}

while ( sum > original && exponent >= 0 ){

if ( sum - Math.pow ( 2 , exponent ) >=  original ) {

sum -= Math.pow ( 2 , exponent ) ;
bin -= Math.pow ( 10 , exponent ) ;

}

exponent-- ;

}

return bin ;

}

}


And this is the output

Binary      Octal       Hexadecimal
1           1           1
10           2           2
11           3           3
100           4           4
101           5           5
110           6           6
111           7           7
1000          10           8
1001          11           9
1010          12           A
1011          13           B
1100          14           C
1101          15           D
1110          16           E
1111          17           F
10000          20          10
10001          21          11
10010          22          12
10011          23          13
10100          24          14
10101          25          15
10110          26          16
10111          27          17
11000          30          18
11001          31          19
11010          32          1A
11011          33          1B
11100          34          1C
11101          35          1D
11110          36          1E
11111          37          1F
100000          40          20
100001          41          21
100010          42          22
100011          43          23
100100          44          24
100101          45          25
100110          46          26
100111          47          27
101000          50          28
101001          51          29
101010          52          2A
101011          53          2B
101100          54          2C
101101          55          2D
101110          56          2E
101111          57          2F
110000          60          30
110001          61          31
110010          62          32
110011          63          33
110100          64          34
110101          65          35
110110          66          36
110111          67          37
111000          70          38
111001          71          39
111010          72          3A
111011          73          3B
111100          74          3C
111101          75          3D
111110          76          3E
111111          77          3F
1000000         100          40
1000001         101          41
1000010         102          42
1000011         103          43
1000100         104          44
1000101         105          45
1000110         106          46
1000111         107          47
1001000         110          48
1001001         111          49
1001010         112          4A
1001011         113          4B
1001100         114          4C
1001101         115          4D
1001110         116          4E
1001111         117          4F
1010000         120          50
1010001         121          51
1010010         122          52
1010011         123          53
1010100         124          54
1010101         125          55
1010110         126          56
1010111         127          57
1011000         130          58
1011001         131          59
1011010         132          5A
1011011         133          5B
1011100         134          5C
1011101         135          5D
1011110         136          5E
1011111         137          5F
1100000         140          60
1100001         141          61
1100010         142          62
1100011         143          63
1100100         144          64
1100101         145          65
1100110         146          66
1100111         147          67
1101000         150          68
1101001         151          69
1101010         152          6A
1101011         153          6B
1101100         154          6C
1101101         155          6D
1101110         156          6E
1101111         157          6F
1110000         160          70
1110001         161          71
1110010         162          72
1110011         163          73
1110100         164          74
1110101         165          75
1110110         166          76
1110111         167          77
1111000         170          78
1111001         171          79
1111010         172          7A
1111011         173          7B
1111100         174          7C
1111101         175          7D
1111110         176          7E
1111111         177          7F
10000000         200          80
10000001         201          81
10000010         202          82
10000011         203          83
10000100         204          84
10000101         205          85
10000110         206          86
10000111         207          87
10001000         210          88
10001001         211          89
10001010         212          8A
10001011         213          8B
10001100         214          8C
10001101         215          8D
10001110         216          8E
10001111         217          8F
10010000         220          90
10010001         221          91
10010010         222          92
10010011         223          93
10010100         224          94
10010101         225          95
10010110         226          96
10010111         227          97
10011000         230          98
10011001         231          99
10011010         232          9A
10011011         233          9B
10011100         234          9C
10011101         235          9D
10011110         236          9E
10011111         237          9F
10100000         240          A0
10100001         241          A1
10100010         242          A2
10100011         243          A3
10100100         244          A4
10100101         245          A5
10100110         246          A6
10100111         247          A7
10101000         250          A8
10101001         251          A9
10101010         252          AA
10101011         253          AB
10101100         254          AC
10101110         256          AE
10101111         257          AF
10110000         260          B0
10110001         261          B1
10110010         262          B2
10110011         263          B3
10110100         264          B4
10110101         265          B5
10110110         266          B6
10110111         267          B7
10111000         270          B8
10111001         271          B9
10111010         272          BA
10111011         273          BB
10111100         274          BC
10111101         275          BD
10111110         276          BE
10111111         277          BF
11000000         300          C0
11000001         301          C1
11000010         302          C2
11000011         303          C3
11000100         304          C4
11000101         305          C5
11000110         306          C6
11000111         307          C7
11001000         310          C8
11001001         311          C9
11001010         312          CA
11001011         313          CB
11001100         314          CC
11001101         315          CD
11001110         316          CE
11001111         317          CF
11010000         320          D0
11010001         321          D1
11010010         322          D2
11010011         323          D3
11010100         324          D4
11010101         325          D5
11010110         326          D6
11010111         327          D7
11011000         330          D8
11011001         331          D9
11011010         332          DA
11011011         333          DB
11011100         334          DC
11011101         335          DD
11011110         336          DE
11011111         337          DF
11100000         340          E0
11100001         341          E1
11100010         342          E2
11100011         343          E3
11100100         344          E4
11100101         345          E5
11100110         346          E6
11100111         347          E7
11101000         350          E8
11101001         351          E9
11101010         352          EA
11101011         353          EB
11101100         354          EC
11101101         355          ED
11101110         356          EE
11101111         357          EF
11110000         360          F0
11110001         361          F1
11110010         362          F2
11110011         363          F3
11110100         364          F4
11110101         365          F5
11110110         366          F6
11110111         367          F7
11111000         370          F8
11111001         371          F9
11111010         372          FA
11111011         373          FB
11111100         374          FC
11111101         375          FD
11111110         376          FE
11111111         377          FF
100000000         400         100


You should use the same format for both the headers and the contents of the table.

It pays to read the documentation. The task could be accomplished very simply.

public static void main(String[] args) {
String tableFmt = " %11s %11s %11s\n";

Your choice of the base-two representation using an int rather than a String (using one hundred one to represent five) is very unconventional and not recommended.
You have also abused method overloading. The base parameter is unused. Rather, you are relying on just the type of the second parameter to pick which method to call.