what is java function

A function in Java is also called a method, which is an independent code block defined in a class to implement a certain function; its function is to improve the reusability and readability of the code. The syntax format of the function is "modifier return value type function name (formal parameter type 1 parameter name 1...) {function body statement; return return value;}".

#This article will introduce the definition and use of Java functions.

A function is an independent block of code defined in a class to implement a certain function. In Java, functions are also called methods.

Why do we need functions?

The purpose is to improve the reusability and readability of the program.

Functions are all run in stack memory; the running function is on the top of the stack.

Function format

修饰符 返回值类型 函数名(形式参数类型1  参数名1,形式参数类型2  参数名2,形式参数类型3  参数名3......)
{
    函数体语句;
    return  返回值;
}

Description:

Modifier: public public static static

Return value type: It is the data type of the functional result implemented by the function.

Method name: Define it yourself, as long as it conforms to the identifier naming rules; camel case naming rules: the first letter of a single word is lowercase, and the first letter of the word after multiple words is capitalized.

Parameter list: That is, the formal parameter list, used to receive actual parameters.

Parameter type: the data type of the parameter

Parameter name: that is, the variable name

Function body statement: It is the function to be completed by the function

return: use To end the function

Return value: that is, the result of the function of this function, which is brought back to the calling place by return.

Note: void means that the return value type is uncertain. It cannot be understood as no return value, but the type of the return value is uncertain;

In addition, the return value type is When void, because the return value type cannot be determined, formal parameter variables cannot be defined to receive it;

When the return value type is void, return does not need to be written; but when the return value type is other such as int String, etc. It must be written when necessary, otherwise compilation errors will occur.

Three steps to customize a function

Determine the return value type

Determine the method name

Clear the parameter list

Parameter transfer of function

Formal parameters: The parameters when the function is defined are formal parameters------>referred to as formal parameters

Actual parameters: The parameters when calling the function are actual parameters------>referred to as actual parameters

Parameter passing: only actual parameters can be passed to formal parameters

Note:The actual parameters and formal parameters must be consistent in number, order, and type.

Example: Writing a sub-function that calculates the sum of two numbers requires keyboard input:

import java.util.Scanner;//导入键盘录入的类 Scanner
class Demo_1
{
	public static void main(String[] args)
	{
		Scanner sc=new Scanner(System.in);//创建键盘录入类Scanner 的对象
		System.out.println("请输入第一个正整数");
		int num1=sc.nextInt();//通过对象sc调用Scanner类中的nextInt()方法读取输入的数据并进行存储
 
 
		System.out.println("请输入第二个正整数");
		int num2=sc.nextInt();
 
 
		int sums=add(num1,num2);//函数调用：定义一个int型的变量来接收和
		System.out.println("sums="+sums);
 
 
	}
	public static int add(int a,int b)//求和函数 子函数
	{
		int sum;
		sum=a+b;
		return sum;
	}
}

Result:

1
2
sum=3

The above is the detailed content of what is java function. For more information, please follow other related articles on the PHP Chinese website!