"Three" Java basics

① data types: Basic data types and reference data types

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Underlying data type: numeric (integer type Byte,short,int,long floating-point type float,double), character type, Boolean

Reference data types: classes, interfaces, arrays

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② name to be used for hump naming (obey the company's naming convention)

③public class xxxo{

public static void Main (String args []) {

Basic syntax similar to C + +. Net

}

}

Xxxo and Java file names are identical

④system.out.println ("contents of output")

⑤for loops, assignments, judgments, and sequences are similar to dot net and C + +

⑥ output A Boolean result is true and False (C # inside is a Boolean inside Bool,java) (cannot be represented by 0 and not 0!). ）

⑦ASCII Full name is American standard Code for information interchange

The Unicode character set is used in Java.

The difference between ⑧++i and i++

i=5; with int j = i++ + 5; and int j = ++i + 5; the output will tell the difference.

conclusion, ++i in the operation, it is first to add 1 to the operation, i++, is the first operation and then add 1!

⑨ relational operator <,>,<=,>=,==,!=

Boolean Logical operator!,&,|,^,&&,| | Logic and & what's the difference between a short circuit and a &&? Answer: In the short-circuit and && conditions, when one is false, it will no longer continue to judge the following Boolean, so if there is an operation in the following Boolean (such as i++), do not perform the subsequent operation. "Short Circuit and | |" It's not going to be shipped.

public class exerc{

public static void Main (String args main[]) {

System.out.println ("Some basic small rules, judgments, loops, switch are the same as other languages");

}

}

"Three" Java basics