Используй функцию

import java.util.Scanner;

public class Main { public static void main(String[] args) { Scanner scan = new Scanner(System.in); double x = scan.nextDouble(); double y = scan.nextDouble(); double z = scan.nextDouble();

    double result = minMax(x, y, z);
    System.out.printf("%.2f\n", result);
}

public static double minMax(double x, double y, double z) {
    double maxXY = Math.max(x, y);
    double maxYZ = Math.max(y, z);
    double sumXYZ = x + y + z;

    return Math.min(Math.min(maxXY, maxYZ), sumXYZ);
}

}