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 } }
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