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This article will explain in detail how to parse the basic data types and operators of Java. The content of the article is of high quality, so the editor shares it for you as a reference. I hope you will have some understanding of the relevant knowledge after reading this article.

Basic data type

Java is a strongly typed language, and you must specify the data type when declaring variables. The value of the variable (variable) occupies a certain amount of memory space. Different types of variables occupy different sizes. There are 8 basic data types in Java, including 4 integers, 2 floating point types, 1 character type, and 1 Boolean type, as shown in the table below.

Java basic data type

Byte byte type 1 byte 3127 short short integer 2 bytes 3meme 32767 int integer 4 bytes 3 long long integer 8 bytes 3L long 92233720368L long finally there must be an L letter (case indifference) float single precision floating point 4 bytes 1.2F line 223.56F float it is best to have an F letter at last (case does not matter). Double double-precision floating-point type 8 bytes 1.2, 1.2D double 223.56223.56D it is better to have a D letter at last (case doesn't matter). Char character type 2 bytes'a character data can only be one character, enclosed in single quotation marks. Boolean Boolean 1 bit true, false

The numerical types in Java are not unsigned, and their range of values is fixed and will not change with the change of the machine hardware environment or operating system. In fact, there is another basic type in Java, void, which also has a corresponding wrapper class java.lang.Void, but we cannot manipulate them directly. We do not have to force to remember the range of values of the basic types of numeric types, because their values are already defined in the corresponding wrapper class in the form of constants. Take a look at the following example:

Public class PrimitiveTypeTest {public static void main (String [] args) {/ / byte System.out.println ("basic type: byte binary number:" + Byte.SIZE "); System.out.println (" wrapper class: java.lang.Byte "); System.out.println (" minimum: Byte.MIN_VALUE= "+ Byte.MIN_VALUE); System.out.println (" maximum: Byte.MAX_VALUE= "+ Byte.MAX_VALUE); System.out.println () / / short System.out.println ("basic type: short binary number:" + Short.SIZE); System.out.println ("wrapper class: java.lang.Short"); System.out.println ("minimum: Short.MIN_VALUE=" + Short.MIN_VALUE); System.out.println ("maximum: Short.MAX_VALUE=" + Short.MAX_VALUE); System.out.println () / / int System.out.println ("basic type: int binary number:" + Integer.SIZE); System.out.println ("wrapper class: java.lang.Integer"); System.out.println ("minimum: Integer.MIN_VALUE=" + Integer.MIN_VALUE); System.out.println ("maximum: Integer.MAX_VALUE=" + Integer.MAX_VALUE); System.out.println () / / long System.out.println ("basic type: long binary number:" + Long.SIZE); System.out.println ("wrapper class: java.lang.Long"); System.out.println ("minimum: Long.MIN_VALUE=" + Long.MIN_VALUE); System.out.println ("maximum: Long.MAX_VALUE=" + Long.MAX_VALUE); System.out.println () / / float System.out.println ("basic type: float binary number:" + Float.SIZE); System.out.println ("wrapper class: java.lang.Float"); System.out.println ("minimum: Float.MIN_VALUE=" + Float.MIN_VALUE); System.out.println ("maximum: Float.MAX_VALUE=" + Float.MAX_VALUE); System.out.println () / / double System.out.println ("basic type: double binary number:" + Double.SIZE); System.out.println ("wrapper class: java.lang.Double"); System.out.println ("minimum: Double.MIN_VALUE=" + Double.MIN_VALUE); System.out.println ("maximum: Double.MAX_VALUE=" + Double.MAX_VALUE); System.out.println () / / char System.out.println ("basic type: char binary digits:" + Character.SIZE); System.out.println ("wrapper class: java.lang.Character"); / / output Character.MIN_VALUE to console System.out.println ("minimum: Character.MIN_VALUE=" + (int) Character.MIN_VALUE) in numeric rather than character form / / output Character.MAX_VALUE to console System.out.println ("maximum: Character.MAX_VALUE=" + (int) Character.MAX_VALUE) in numeric form instead of character form;}}

Integer type

Integer types include byte, short, int, and long.

Public class Demo1 {public static void main (String [] args) {/ / literal value defaults to int type byte N1 = 12 short N2 = 45 politics int n3 = 456 X long n4 = 67L port / L or l}}

Binary is too long to be distinguished by underscores.

Public class Demo1 {public static void main (String [] args) {int N5 = 0B1010111114001115001100long N8 = 123456787654321L;}}

Floating point type

Floating point types include double and float.

Note: 1. Do not operate between floating-point types that vary widely in magnitude. two。 Avoid making equal judgments

Import java.math.*;public class Demo1 {public static void main (String [] args) {float F1 = 34.5 f / bump f or F defaults to double type double D1 = 456.78d / suffix d or D / double D2 = 2.4e20 double / e or E with 10 as base / / floating point can be expressed in hexadecimal, but it must be expressed in scientific / / numeration, and it is based on p double D3 = 0x3.4p20witch / p or P with 2 double D4 = 2.4e20. Double d5 = d4 + 1 * * double num1 = 0.1 * * double num2 = 0.2 * * double num3 = num1 + num2;//0.3//java.langSystem.out.println (num3 = 0.3); / / different output results falseSystem.out.println (num3); / / output results 0.300000000000004pash / processing java.math package BigDecimal number1 = new BigDecimal ("0.1"); BigDecimal number2 = new BigDecimal (" 0.2"); System.out.println (number1.add (number2)) / / output result 0.3}}

Character type

Char Typ

The char type is a single 16-bit Unicode character; the minimum value is\ u0000 (that is, 0); the maximum value is\ uffff (that is, 65535); the char data type can store any character; example: char letter ='A character;.

Only one character can be stored and only single quotation marks can be used

Boolean type

The boolean type includes true and false

Reference data type String

Public class Demo2 {public static void main (String [] args) {String name = "Guo Jing"; String address = "Beijing"; / / + connection string System.out.println (name+address); int N1 = 1 int N2 = 1 n1+n2 system. Out.println (n1+n2); / / output result: 2 + "Guo Jing"-"2 Guo Jing" System.out.println (n1+n2+name) / / output result: 2 Guo Jing / "Guo Jing 1" + N2-> "Guo Jing 11" System.out.println (name+n1+n2); / / output result: Guo Jing 11}}

Basic data type conversion automatic type conversion

Small-"big low -" high

Forced type conversion

Big-"small high -" low

The syntax format is: (cast data type) Operand

Int num = (int) 45.67

Type promotion principle

Premise: operation result: adopt high type (data type with wide range as result)

Operator

Classification: according to the number of operands

One yuan

Duality

Three yuan

Arithmetic operator

Public class Demo5 {public static void main (String [] args) {System.out.println (5 + 2); / output result: 7System.out.println (5-2); / / output result: 3System.out.println (5 * 2) / / output result: 10 impulse-division-/ / the divisor and divisor are both integers. The result will be taken as an integer part System.out.println (5 / 2); / output result: 2System.out.println (5 / 2); / / output result: 2.5System.out.println (5 / 2) / / output result: 2.5System.out.println (5.0 / 2.0); / / output result: 2.5 stroke / divisor 0 throw exception / / System.out.println (5 / 0); System.out.println (5.0 / 0); / / positive infinity output result: InfinitySystem.out.println (- 5.0 / 0); / / negative infinity output result:-Infinity// non-digital NaNSystem.out.println (0.0 / 0) / / output result: NaN//- takes remainder and module-System.out.println (5% 2); / / output result: 1System.out.println (5.0% 2); / / output result: 1.0System.out.println (5%-2) / / output result: 1System.out.println (- 5% 2); / / output result:-1, divisor / /-exercise explanation-/ * calculate the number of weeks and the number of days remaining according to the number of days (46) * / int days = 46 int week = days / 7 / week int day = days% 7 / / System.out.println (week+ "week, remainder" + day+ "days"); / /-/ * for a randomly entered 3-digit number, reverse For example: 432*/int num = 234 inverted (output each number inverted): 432*/int num = 234 System.out.println (n1*100+n2*10+n3) / / "432" System.out.println (n1*100+n2*10+n3); / / "432" System.out.println (n1*100+n2*10+n3); / / 432}

Relational operator logic operator

& & | short circuit and short circuit or

Bit operator

& | non-short circuit and non-short circuit or

5 binary 00000000-00000000-00000000-00000101 2 binary 00000000-00000000-00000000000-00000010prime & if the corresponding bits are all 1, the result is 1, otherwise it is 05binary 00000000-00000000-0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000-00000000000-00000111p / ^ if the corresponding bits are the same, the result is 0. Otherwise, it is 15 ^ 2 binary 00000000-00000000-00000000-0000000000Universe. The bitwise complement operator flips every bit of the Operand, that is, 0 becomes 1, 1 becomes 0. ~ 5 binary 11111111-11111111-11111111-11111010 minus one 1111111111111111111111111111111001 take the inverse 00000000000000000000000000110 / 2 binary 00000000000000000000000000001hand / > unsigned right shift, the left high bits are all filled with 0 5 > 2 binary 00000000-00000000-0000000001-6 > 2 binary 00001111-1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111

Extended assignment operator conditional operator

Syntax:

Comparison operation | | Boolean? Expression 1: expression 2

If? The previous result is that true returns expression 1, if? Return false before returning expression 2

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