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This article introduces the relevant knowledge of "what are the basic grammars of Java". In the operation of actual cases, many people will encounter such a dilemma. Then let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Operation between variables of 7 basic data types

When the variable of the data type with small capacity is calculated with the variable of the data type with large capacity, the result is automatically promoted to the data type with large capacity.

Byte, char, short-> int-- > long-- > float-- > double

Special: when the variables of byte, char and short are operated, the result is int.

Description: the capacity size at this time refers to the size and size of the range of numbers. For example, the capacity of float is greater than that of long.

Char clocked errors; / / compilation error, the char type has and can only put one character.

String types are converted to various numeric types:

String s = 123 + ""

Int num = Integer.paserInt (s)

Convert the numeric type to the string type:

String s = String.valueOf (value); / / where value is any numeric type.

The binary conversion method of the Integer class:

Static String toBinaryString (int I)

Static String toHexString (int I)

Static String toOctalString (int I)

If the program can use both ternary operators and if-else structures, then ternary operators are preferred, which is concise and efficient.

The method of converting String type to character type:

Public char charAt (int index) / / Index starts at 0

Switch..case is slightly more efficient than if..else.

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