Looking back java-based (a) data types and operators ----

This paper re-learn the details about the missing records before the foundation of the Java school.

1. java belong to a strongly typed language

2.8 kinds of basic data types: byte, short, int, long, float, double, char, boolean, as automatic data type conversion:

　　byte, char, short ---> int ---> long ---> float ---> double, to note that:

• boolean data type not automatically converted.
• When operation between byte, char, short int result type.

  1 class ByteTest{
  2     public static void main(String[] args){
  3         byte a = 3;
  4         byte b = 4;        
  5         byte c = a + b;
  6         System.out.println(c);
  7         
  8     }
  9 }

  

• When direct byte b = 3 + 4; correct result is output.

• Depending on storage, float is greater than double the capacity.
• After long type to add "l" or "L", if not, then will default to the int type, int when out of range of error.
•  

 

• 
• float and long similar.

3. Since the increase does not change the original data types

    

public  static  void main (String [] args) {
         Short S =. 3 ; 
        S + =. 1; // do not change the data type
         // S = S + 2; // not compile by 
        System.out.println (S); 
    
    }

 

 Expression 4. switch structures, only six data types: byte, short, char, int, enumerated types, String type. After the case can only declare a constant, you can not be declared range.