/*
Automatic conversion
1. Explicit: The code does not need to be processed, and the conversion
rules are directly completed: the data range is from small to large
*/
public class demo05{ public static void main(String[] args){ System.out.println(30); //Directly output an integer, the default is Int type System.out.println(3.12);//Directly output a decimal, the default is double type long nume1=100;//Data conversion between integers //(1) Left side It is of long type, and the right side is of int type by default. //(2) The equal sign is assigned, and the right side is assigned to the left. //(3) int——>long, which satisfies the data range of the left size and the right size. //(4) This line of code occurs Automatic conversion System .out.println(nume1);//100 double nume2=3.14159267F;//Data conversion between floating point numbers //(1) double on the left, float on the right; //(2) from double ->float; To meet the data range of left size and right size, automatic type conversion also occurs System.out.println(nume2); float nume3 =30L;
//(1) From long->float, the range of float is greater than long, which satisfies the data range of large left and right small
//(2) This line of code is automatically converted
System.out.println(nume3);
}
}
/*Forced conversion
1. Features: The code needs to be processed in a special format and cannot be completed automatically
2. Format: type with a small range + variable name with a small range = (type with a small range) + data with a large range
Note:
1 mandatory Conversion is generally not recommended because of possible data overflow and loss of precision.
2. The three types of byte/short/char can be used for mathematical operations
. 3. When the three types of byte/short/char are operated, they will be first referred to the int type
. Data type conversion
*/
public class demo06{ public static void main(String[] args){ //The left side is int type, the right side is long //long->int, not from small to large, can not be automatically converted after finishing / /Format; data type with small range + variable name with small range = (data type with small range) + original data with large range int nume1=(int)100L; System.out.println(nume1); /* //long ->int (cast) int nume2=6000000000; System.out.println(nume2);//1705032704 overflow */
//double->int (cast)
int nume2=(int)3.99;
System.out.println(nume2);//3 (this is not rounding, but rounding off decimal places) loss of precision
char nuem3='A';//This is a character variable 'A'
System.out.println(nume3+1);//66 that is, the capital letter A is treated as 65 for processing
//The bottom layer of the computer will use A number (binary) to represent the character 'A', which is 65
//Once the char is mathematically operated, the character will be translated into a number according to certain rules
/*
byte number4=40;//The size of the value on the right side Cannot exceed the value range on the left
byte nume5=50;
byte result1=nume4+nume5;//(both will be first mentioned as int type) int+int->int
System.out.println(result1);
*/
/*
Here An error will be reported
*/
//The correct way of writing is as follows:
byte nume4=40;//The size of the value on the right cannot exceed the value range on the left
byte nume5=50;
int result1=nume4+nume5;
//byte+bute->int +int->int
System.out.println(result1);//90
short number6=40;
//byte+short->int+int->int
//int is cast to
short
//Minimum data type + minimum data variable = (minimum data type) + (data with a large original range)
shiort result2=(short)(nume5+nume6);//90
}
}
