Java基础-方法重载

方法重载

java允许同一个类中，多个同名方法的存在，但要求的形参列表不一致

• 使用细节
  1. 方法名：必须相同
  2. 形参列表：必须不同（形参类型或个数或顺序，至少有一样不同，参数名无要求）
  3. 返回类型：无要求

代码示例：

public class OverLoadExercise {
    public static void main(String[] args) {
        Method m = new Method();

        int res1 = m.max(1, 5);
        double res2 = m.max(1.1, 1.8);
        double res3 = m.max(4.2, 5.1, 3.6);
        
        if (res1 != -1) {
            System.out.println("the largest int variable between two variables is " + res1);
        }
        else {
            System.out.println("variables are equal!");
        }
        if (res2 != -1) {
            System.out.println("the largest double variable between two variables is " + res2);
        }
        else {
            System.out.println("variables is equal!");
        }
        if (res3 != -1) {
            System.out.println("the largest double variable between three variables is " + res3);
        }
        else {
            System.out.println("variables is equal!");
        }

        
        double res4 = m.max(4.2, 5.1, 3);

        if (res4 != -1) {
            System.out.println("the largest double variable between three variables is " + res4);
        }
        else {
            System.out.println("variables is equal!");
        }
    }
}

class Method {
    public int max(int a1, int a2) {
        int max;
        if (a1 > a2) {
            max = a1;
            return max;
        }
        else if (a2 > a1) {
            max = a2;
            return max;
        }
        else {
            return -1;
        }
}
public double max(double a1, double a2) {
    double max;
    if (a1 > a2) {
        max = a1;
        return max;
    }
    else if (a2 > a1) {
        max = a2;
        return max;
    }
    else {
        return -1;
    }
}

public double max(double a1, double a2, double a3) {
    double max;
    if (a1 > a2 && a1 > a3) {
        max = a1;
        return max;
    }
    else if (a2 > a1 && a2 > a3) {
        max = a2;
        return max;
    }
    else if (a3 > a1 && a3 > a2) {
        max = a3;
        return max;
    }
    else {
        return -1;
    }
}

public double max(double a1, double a2, int a3) {
    System.out.println("this method running!");
    double max;
    if (a1 > a2 && a1 > a3) {
        max = a1;
        return max;
    }
    else if (a2 > a1 && a2 > a3) {
        max = a2;
        return max;
    }
    else if (a3 > a1 && a3 > a2) {
        max = a3;
        return max;
    }
    else {
        return -1;
    }
}

}

运行示例：

the largest int variable between two variables is 5
the largest double variable between two variables is 1.8
the largest double variable between three variables is 5.1
this method running!
the largest double variable between three variables is 5.1