Java方法（四）

设计方法原则：本意为功能块，是实现某个功能语句块的结合，设计方法时保持原子性（一个方法完成一个功能）

public class operator {public static void main(String[] args) {int sum = add(1,3);System.out.println(sum);}//加法public static int add(int a,int b){return a+b;}
}

 方法的定义以及调用

public class operator {public static void main(String[] args) {
int str = str(2,4);System.out.println(str);}public static int str(int a,int b){int result = 0;if (a==b){System.out.println("a=b");return 0;}if (a>b){result = a;}else {result = b;}return result;}
}

方法重载

public class operator {public static void main(String[] args) {
double str = str(2.5,4.2);System.out.println(str);}public static int str(int a,int b){int result = 0;if (a==b){System.out.println("a=b");return 0;}if (a>b){result = a;}else {result = b;}return result;}public static double str(double a,double b){double result = 0;if (a==b){System.out.println("a=b");return 0;}if (a>b){result = a;}else {result = b;}return result;}
}也可以通过强制转换进行重载方法

public class operator {public static void main(String[] args) {double sum = add(3.6,4.9);System.out.println(sum);}public static int add(int a,int b){return a+b;}public static long add(long a,long b){return a-b;}public static double add(double a,double b){return a*b;}
}

命令行传参

public class operator {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]);}}}//主要在于使用命令行进行编译，运行，重在路径名

可变参数（不定向参数，指定参数后加.....，只能放在最后）

public class operator {public static void main(String[] args) {
printMax(12,43,56,73.3,21,1,9,5);
printMax(new double[]{1,2,3});}public static void printMax(double...numbers){if (numbers.length==0){System.out.println("No argument passed");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（自己调用自己，如计算阶乘）

public class jiabaoyu {public static void main(String[] args) {//阶层计算System.out.println(f(5));}public static int f(int n){if (n==1){return 1;}else {return n*f(n-1);}}
}//边界条件；前阶段；返回阶段：[n*(n-1)];栈机制；适用于基数较少的运算