You want to display an integer as a series of bits, for example when interacting with certain hardware devices. You want to convert a binary number or a hexadecimal value into an integer.

The class
`java.lang.Integer`

provides the solutions. Use
`toBinaryString( )`

to convert an integer to binary.
Use `valueOf( )`

to
convert a binary string to an
integer:

// BinaryDigits.java String bin = "101010"; System.out.println(bin + " as an integer is " + Integer.valueOf(bin, 2)); int i = 42; System.out.println(i + " as binary digits (bits) is " + Integer.toBinaryString(i));

This program prints the binary as an integer, and an integer as binary:

$ java BinaryDigits 101010 as an integer is 42 42 as binary digits (bits) is 101010 $

`Integer.valueOf( )`

is more general than binary
formatting. It will also convert a string number from any radix to
`int`

, just by changing the second argument.
Octal is base 8,
decimal is 10, hexadecimal 16. Going the other way, the
`Integer`

class includes `toBinaryString( )`

,
`toOctalString( )`

, and `toHexString( )`

.

The `String`

class itself includes a series of
static methods, `valueOf(int)`

,
`valueOf(double)`

, and so on, that also provide
default formatting. That is, they return the given numeric value
formatted as a string.

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