How to write java function

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

The main function of the function is to improve the reusability of the code.

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 （  [    参数类型1 参数名1,参数类型2 参数名2....  ]  ）{
               //   [    ]    里面表示可选项，即参数不是必须的
                执行语句...
                return  返回值；    //返回值的类型必须与返回值类型一致
                  }

Description:

Modifier: It can be an access modifier or a function modifier (abstract, final, static, synchronized), It can also be a combination of both.

Return value type: The data type used to limit the function return value.

Parameter type: used to limit the data type passed when calling the function.

Parameter name: It is a variable used to receive the data passed when calling the method.

return: Used to receive methods and return values ​​of the specified type from the function.

Return value: This value will be returned to the caller of the function.

Example:

public class method {
    /*
     * 程序入口,主函数 .
     * 
     * @ 方法 <==> 函数,指的是同一个东西.
     */
    public static void main(String[] args) {
	// 通过函数名调用
	method01();
 
	method02(9, 3);
	System.out.println("5+6=" + add(5, 6));
    }
 
    /*
     * @ 函数的格式为：
     * 
     * @ 访问修饰符 返回值类型 函数名(参数类型1 参数名1,参数类型2 参数名2....){
     * 
     * @ 执行语句
     * 
     * @ return 返回值;//返回值的类型必须与返回值类型一致
     * 
     * @ }
     */
    /*
     * @ 声明一个静态函数method01() 无参数无返回值
     */
    static void method01() {
	System.out.println("这是method01方法,可以通过method01();调用.");
	// 这个return可以省略.每个函数都是以return结束,返回到函数调用处
	return;
    }
 
    /*
     * 有参数无返回值
     */
    static void method02(int num1, int num2) {
	method01();
	System.out.println("这是method02方法,第一个参数是" + num1 + "第二个参数是" + num2);
    }
 
    /*
     * 有返回值的返回值类型要和要返回的数据类型一致
     * 
     * @ 例如：计算两个整数的和,结果仍然是整型,返回值类型为int.返回值类型可以说基本数据类型，也可是自定义的数据类型
     */
    static int add(int num1, int num2) {
	int sum = 0; // 声明一个整形变量并初始化为0
	sum = num1 + num2;// 将num1和num2的和赋值给sum
	return sum;// 将sum的值返回到调用处
    }
 
}

For more java knowledge, please pay attention to java basic tutorial.

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