A detailed description of the return value types of Java functions and examples of generating random numbers

Four elements of a function: function name, input, output (return), processing.

There are two types of functions: one is a return-worthy function, and one is a function that has no return Value.

1.

Definition: a function that has no return value: ( when I do not need the result of the function to be computed, I do not need to have a return value, directly in the function of the operation to complete the processing can Be)

static void function name (parameter) {

function body

}

Call: call a function with no return value: function name (actual parameter);

The argument in the function is called the virtual parameter, and we need to give him an actual parameter to complete the whole operation FLOW.

For example: I want to print a one or two number of the and?

 public class　　HS {    publicstaticvoid  main (string[] Args) {                    Jisuan (3,5); 3, 5 is the actual parameter assigned to a, B value (position must correspond!) )    }    // function with no return type    staticvoid Jisuan (int a,int  b) {        int c=a+b;        System.out.println (c);    }   }                

Of course the parameters are determined according to the situation, if there are no parameters you do not need to write parameters:
For example: randomly generate a four-digit number?

 public classHS { public Static voidmain (string[] Args) {suiji (); }    //a function with no return type generates a random four-digit number;    Static voidSuiji () {
    //the outer layer defines an empty string to stitch the integer type a;String s= "";
    //because it is the output of a four-bit number, so I want to loop four times each time output a number         for(inti=0;i<4;i++){             intA= (int) (math.random () *100000000);//math.random () Molding method: calls all numbers between 0-1. This number must be a decimal, and//for 10, then A is the single digit.//This number is likely to be 0.00000001654 or more of 0, so try to take a larger number in the backa=a%10;//because it is always a double with a decimal number, it is forced to be converted to type int, because our purpose//because A is an int type, and I want to output a string,//is to output a 4-bit positive number. //so I'm going to define an empty string on the outer layer to stitch up a,//integer and string concatenation will automatically change to string s=s+a;s+=a;    } System.out.println (s); }    }

2.

Definition: a function with a return value: ( if you need to return a value to participate in another operation, the function must have a return type when it is defined!) The return type represents the type of merit to Return.

Static return type function name (parameter) {

function body

Return variable;

}

Call: call a function that has a return value: the return type variable = function name (parameter);

Example 1:: I want to print two numbers of the and?

 public classHS { public Static voidmain (string[] Args) {intA=he (5,6);    System.out.println (a); }    //a function that has a return value;    Static intHeintAintB) {        intc=a+b; returnc; }    }
One:
The same is true for printing two numbers and a few points when I need to have a return value:
1. Return type must be consistent with the type of the return value
2. Call the first write data type (return value Type) variable name = function name (parameter);
This function is then called up.

Two:
For this return type, use it flexibly. For example, or the above question, what if I want to output a string of type strings?
1. first, when defining a function, the return type will be string;
The value returned by 2.return must also be of type string
3. The data type when the function is called again is the string type
The code is as Follows:
It does not lie in: integer type after the operation or integral type, if you want to output an integer type will not need to convert.
If you want to output a string, you need to define an empty string in the function weight to splice with the result, and the integer value is automatically converted to a string during stitching.

 public  class   HS { public   Static  void   main (string[] Args) {String a<        /span>=he (5,6 //  a function with a return value;  static  String He (int  a,int          B) {String s  = ";         int  c=a+b;        s  +=c;     return   s; }} 
  

Example 2: randomly generate a four-digit number? (there is a return value, because it is a random 4-digit array of 4-bit strings, so the return type here is string, not int.) But can make int[] Array)

 public classHS { public Static voidmain (string[] Args) {String n=SJ ();    System.out.println (n); }    //a function with a return type, randomly generating four-digit numbers;    StaticString SJ () {string s="";  for(inti=0;i<4;i++){            intA= (int) (math.random () *10000000); A=a%10; S=s+a; }        returns; }    }

A detailed description of the return value types of Java functions and examples of generating random numbers