Java vs. binary conversion

1. Java Features: Portability, object-oriented, open source, robustness

2. JDK,JRE,JVM:

A) JDK:Java Development Kit Java Runtime package (includes JRE and JVM)

b) JRE:Java Runtime Environment Java Run environment (contains JVM)

c) JVM:java virtual machine

3. about configuring environment variables:

A) path: files needed for Java compilation

b) classpath: Find the path to the . class file for your virtual machine

4 . Keywords cannot be used as identifiers; goto and const are java keywords

5. Java data type:

A) basic data type:

I. integral type: Byte, short,int,long

II. Float type: float,double

III. character type: char

Iv. Boolean type: Boolean

b) Reference data type: Class, interface, array, etc.

6,1 byte = 8 bit

7, Byte：1char:2 byte int:4 byte long :8float:4 byte

8. escape characters: \ n : newline \ t : space \ r : Enter

9. Float Flo = 3.14f

10, long lo = 123456789l

11, into the system:

(1) decimal ----binary:

such as: decimal number to binary binary :

The remainder

Divide by 2 50..............0

Divide by 2 25..............0

Divide by 2 12..............1

Divide by 2 6................0

Divide by 2 3................0

Divide by 2 1................1

Divide by 2 0................1

inverse fetch remainder: binary number: 1100100

(2) binary--- decimal:

such as: binary number 1100100 to decimal

1 1 0 0 1 0 0

1*2 ' 6 1*2 ' 5 0*2 ' 4 0*2 ' 3 1*2 ' 2 0*2 ' 1 0*2 ' 0

(starting from the single digit, 2 of the 0- Time Square)

64 32 0 0 4 0 0

The result would be to add a decimal number of: 100

(3) Binary turn octal:

such as binary number 1100100 to eight binary:

XX1

(Start in Bits, 3 for a group, less than 3 to the left to 0 )

0*2 ' 2+0*2 ' 1+1*2 ' 0 1*2 ' 2+0*2 ' 1+0*2 ' 0 1*2 ' 2+0*2 ' 1+0*2 ' 0

1 4 4

Get octal number: 0144

(4) octal turn binary:

such as octal 0324 to binary :

0 3 2 4

divided by 2     0...0      1 ..... 1          1 ..... 0           2 ... 0

divided by 2                  0 ..... 1        0 ..... 1          1 ... 0

0 ... Yu 1

Separate reverse-fetching

00

Less than 3 bits, 0- padded left

The binary is obtained: 011010100(leftmost 0 can be omitted)

(5) binary turn hex

Binary number: 11010100:

1101 0100

1*2 ' 3+1*2 ' 2+0*2 ' 1+1*2 ' 0 0*2 ' 3+1*2 ' 2+0*2 ' 1+0*2 ' 0

8+4+1=13 for D 4

(Number 0--9, starting from the letter a )

That is, Hex: 0xd4

(6) hex turn binary:

Hexadecimal number 0xd4:

(The letter D represents the numbers respectively:)

13 4

Divide by 2 6 ... remainder 1 2 ..... Yu 0

Divide by 2 3 ... remainder 0 1 ..... Yu 0

Divide by 2 1 ... remainder 1 0 ..... Yu 1

Divide by 2 0 ... Yu 1

The remainder is reversed respectively, less than 4 bits to the left with 0 :

1101 0

That gets the binary number: 11010100

Java vs. binary conversion