When the data is not the same type, data type conversion will occur.
Automatic type conversion (implicit)
1. Features : code does not need special treatment, automatically.
2. Rules : data range from small to large .
Casts (explicit)
First, the automatic type transcoding
. 1 public class Demo01DataType { 2 public static void main (String [] args) { . 3 System.out.println (1024); // this is a integer, the default is to type int . 4 System.out.println (3.14); // this is a floating-point number, the default is a double 5 6 // left is a long type, the right is the default type int, not the same around 7 // a equals sign represents the assignment, the int constants on the right, to the left side stores long variable . 8 // int -> long, in line with the data range from small to large in claim 9 // this line of code type conversion occurs automatically. 10 Long num1 = 100 ; . 11 System.out.println (num1); //100 12 is 13 is // left type double, the right side is a float type, not about the same as 14 // float -> double, from small to large compliance rules 15 // also place automatic conversion 16 double num2 = 2.5F ; . 17 System.out.println (num2); // 2.5 18 19 // left is the float type, the type of right is long, left and right are not the same 20 // long -> float, float range is larger, in line with small to large rule 21 // also place automatic conversion 22 is a float num3 = 30L ; 23 is System.out.println (num3); // 30.0 24 }
operation result
1024
3.14
100
2.5
30