The use and recursive algorithm of Java language methods

1. What is a method (function)

The Java language approach is similar to a function in other languages, a piece of code that accomplishes a particular function,

2. Statement of methods of mastery

Declaration format: Modifier return value type method name (parameter list) {

program code;

return value is returned;

}

Parameters in the method:

Formal parameters: Used to receive data from outside input when the method is invoked.

Actual parameter: The data that was actually passed to the method when the method was called.

The return value in the method (return value type: The data type of the result to be returned by the method, such as a method that does not return a value, must be given the return value type void)

(return value: The data that the method returns to the caller after execution has completed.) ）

(The return statement terminates the run of the method and specifies the data to be returned.) ）

3. Mastering the Call of the method

The Java language uses the following form to invoke the method:

The name of the object variable. Method name (argument list);

The number of arguments, the data type and order must match the parameter list of the called method declaration.

The code is as follows:

　　

public class demo11{

public static void Printinfor () {

for (int i = 0; i<10; i++) {
System.out.println (i);
}

}
public static int Getmax (int i, int j) {

int max=0;
if (i>j) {
Max=i;
}
else {
Max=j;
}
return Max;

}

public static void Main (String [] args) {

System.out.println ("First time printing");
Printinfor ();
System.out.println ("Second-time printing");
Printinfor ();
System.out.println ("compare two numbers output larger number:");
int res = Getmax (2,4);
System.out.println (RES);

}


}

　　　　

4. Mastering what is a method of overloading

Overloading of methods refers to multiple methods in a class that can be defined with the same name but with different parameter lists, and when called, the corresponding method is selected according to the different parameter lists;

A parameter list refers to the type, number, or order of parameters.

An overload that satisfies a point that is a method:

1. Occurs in the same class

2. Method names are the same

3. Different parameter list (type, size, quantity)

The code is as follows:

public class demo11{
public static int Getmax (int i, int j) {

int max=0;
if (i>j) {
Max=i;
}
else {
Max=j;
}
return Max;

}
public static int Getmax (int i, int j, int k) {
int max= (I&GT;J)? I:j;
if (max>k) {
return Max;
}
else{
return k;
}

}

public static void Main (String [] args) {
System.out.println ("compare two numbers output larger number:");
int res1 = Getmax (2,4);
System.out.println (RES1);
System.out.println ("compare three numbers output larger tree:");
int res2 = Getmax (3,5,4);
System.out.println (Res2);

}


}

5. Understanding Recursive algorithms

1. Recursive invocation refers to the invocation of the method itself that occurs during method execution.

2. The key to recursive algorithms is to capture:

Recursive exit

Push Step to exit approximation

The code is as follows:

　　

public class Demo12
{
public static int multip1 (int n)//method that generally asks for factorial.
{
int res = 1;
for (int i=1; i<=n; i++)
{
Res*=i;
}
return res;
}
public static int multip2 (int n)
{
if (n==1 | | n==0)
{
return 1;
}
Return n*multip2 (n-1);
}
public static void Main (String [] args)
{
System.out.println (MULTIP1 (3));
System.out.println (MULTIP2 (7));
}
}

　　　　　　

　　

The use and recursive algorithm of Java language methods