Circular statements and arrays

Loop statements and arrays

 Summary of knowledge points :  Loop statement      And    Array     
Java There are three main cyclic structures ：1) for loop       2)  while loop    3)  do…while loop        Java  enhance  for  loop  
 One . for( initialization ; Boolean expression ; to update ){  Code statements }    example 1:

 Two .while  loop        while It's the most basic cycle , Its structure is ：
 Format  :   while(  Boolean expression ){ Cycle content }             example 2:

 3、 ... and 、do...while loop   do…while  Circulation and  while  Cyclic similarity , But the difference is ,do…while  The loop will execute at least once 
 Format :   do{  Code statements }while( Boolean expression );   example 3:

 Four 、Java Enhanced for loop Java5  A kind of enhanced array is introduced for loop . But one thing to note ：Java Enhanced for Cycle can only   Value , Can't assign a value 
 Format :   for( Statement statement : expression ){  Code sentence  }
 5、 ... and 、break、continue、return 
1.)break :  End of cycle   2.) continue :  End this cycle , Enter next cycle 
3.)return :  End a way , The method is over , The cycle is naturally ended notice ： stay while and do...while Use in continue Pay attention to the position of the updated statement .
 5、 ... and . Declare array variables 
 notes : Array variables must be declared , To use arrays in a program . The following is the syntax format for declaring array variables ：
 example :  Declare array variables   byte[] arrayByteA;           int[] arrayIntA;              long[] arrayLongA;               String[] arrayStringA;
1) Array initialization mainly includes   Two ways ： initiate static    ,       dynamic initialization 
*  Array static initialization :      arrayByteA=new byte[] {1,2,3,4,5};
 Or array declared variables and initialization are completed in one statement   byte[] arrayByteA=new byte[] {1,2,3,4,5,6};

* Array dynamic initialization     arrbtC=new int[8];
 Or array declared variables and initialization are completed in one statement  int[] arrbtC=new int[2];
2) An array reference 
Java Reference array elements by subscript in ：arrayName[index];
Java The array elements will be checked for out of bounds to ensure security . Each array has one length Property to indicate its length ,
 for example arrayIntA.length  Indicates the array  arrayIntA  The length of .