How to convert BigInteger to String in java

Question

I converted a String to BigInteger as follows   Scanner sc new Scanner System in   System out println  enter the message    String msg sc next    byte   bytemsg msg getBytes    BigInteger m new BigInteger bytemsg      Now I want my string back  I m using m toString   but that s giving me the desired result   Why  Where is the bug and what can I do about it

User · Answer

Use m toString   or String valueOf m    String valueOf uses toString   but is null safe

User · Answer

You want to use BigInteger toByteArray    String msg    Hello there    BigInteger bi   new BigInteger msg getBytes     System out println new String bi toByteArray         prints  Hello there     The way I understand it is that you re doing the following transformations     String  ----------------- gt  byte   ------------------ gt  BigInteger           String getBytes           BigInteger byte      And you want the reverse     BigInteger ------------------------ gt  byte   ------------------ gt  String              BigInteger toByteArray            String byte      Note that you probably want to use overloads of String getBytes   and String byte    that specifies an explicit encoding  otherwise you may run into encoding issues

User · Answer

You can also use Java s implicit conversion   BigInteger m   new BigInteger bytemsg    String mStr        m      mStr now contains string representation of m

User · Answer

How to solve BigDecimal  amp  BigInteger and return a String     BigDecimal x   new BigDecimal  a      BigDecimal y   new BigDecimal  b       BigDecimal result   BigDecimal ZERO    BigDecimal result   x add y     return String valueOf result

User · Answer

String input    0101   BigInteger x   new BigInteger   input   2    String output   x toString 2

User · Answer

To reverse  byte   bytemsg msg getBytes       you can use  String text   new String bytemsg      using a BigInteger just complicates things  in fact it not clear why you want a byte     What are planing to do with the BigInteger or byte    What is the point

User · Answer

https   docs oracle com javase 1 5 0 docs api java lang Object html   Every object has a toString   method in Java

User · Answer

When constructing a BigInteger with a string  the string must be formatted as a decimal number  You cannot use letters  unless you specify a radix in the second argument  you can specify up to 36 in the radix  36 will give you alphanumeric characters only  0-9 a-z   so if you use this  you will have no formatting  You can create      new BigInteger  ihavenospaces   36  Then to convert back  use a      toString 36   BUT TO KEEP FORMATTING  Use the byte   method that a couple people mentioned  That will pack the data with formatting into the smallest size  and allow you to keep track of number of bytes easily  That should be perfect for an RSA public key crypto system example program  assuming you keep the number of bytes in the message smaller than the number of bytes of PQ   I realize this thread is old

User · Answer

Why don t you use the BigInteger String  constructor   That way  round-tripping via toString   should work fine    note also that your conversion to bytes doesn t explicitly specify a character-encoding and is platform-dependent - that could be source of grief further down the line

[java] How to convert BigInteger to String in java

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