Day05__方法

方法

何为方法？

package method;

//何为方法？
public class Demo01 {
    public static void main(String[] args) {
        System.out.println(add(1,2));
    }

    //加法
    public static int add(int num1 ,int num2){
        return num1+num2;
    }
}

方法的定义和调用

package method;

public class Demo02 {
    public static void main(String[] args) {
        System.out.println(max(66,66));
    }

    //比大小
    public static  int max(int num1,int num2){
        int result;
        if(num1>num2){
            result = num1;
        } else if (num1<num2) {
            result = num2;
        }else{
            System.out.println("相等");
            return 0;
        }
        return result;
    }
}

方法重载

package method;

public class Demo02 {
    public static void main(String[] args) {
        int num1 = max(10,20);
        double num2 = max(1.1,2.2);
        System.out.print(num1+","+num2);
    }

    //比大小
    public static  int max(int num1,int num2){
        int result;
        if(num1>num2){
            result = num1;
        } else if (num1<num2) {
            result = num2;
        }else{
            System.out.println("相等");
            return 0;
        }
        return result;
    }

    //比大小
    public static  double max(double num1,double num2){
        double result;
        if(num1>num2){
            result = num1;
        } else if (num1<num2) {
            result = num2;
        }else{
            System.out.println("相等");
            return 0;
        }
        return result;
    }
}

命令行传参

package method;

//命令行传参
public class Demo03 {
    public static void main(String[] args) {
        //args.length 数组长度
        for (int i=0 ; i<args.length ; i++){
            System.out.println("args["+i+"]:"+args[i]);
        }
    }
}

可变参数

package method;

//可变参数
public class Demo04 {
    public static void main(String[] args) {
        Demo04 demo04 = new Demo04();
        demo04.test();

        //调用可变参数的方法
        printMax(32,33,14,4,41);
        printMax(new double[]{1,2,3,4,5});
    }

    public void test(int... i){
        System.out.println(i);
    }


    public static void printMax(double... numbers){
        if (numbers.length == 0){
            System.out.println("No argument oassed");
            return;
        }
        double result = numbers[0];


        for(int i=1 ; i<numbers.length ; i++){
            if(numbers[i]>result){
                result = numbers[i];
            }
        }
        System.out.println("The max value is " + result);
    }
}

递归

package method;

//递归
public class Demo05 {
    public static void main(String[] args) {
        System.out.println(test(5));
    }
    
    //阶乘
    public static int test(int n){
        if (n==1){
            return 1;
        }else {
            return n*test(n-1);
        }
    }
}