Question

/** this is my code, and I want to invoke the method, doubleArraySize() in main method.

and I need to display some result in cmd or terminal.

also, I have classes such as Average and RandomN needed for piping(pipe).

please help me and thank you.

**/

import java.util.Scanner;

public class StdDev {

static double[] arr;

static int N;

public static void main(String[] args) {

if(args.length==0){

arr= new double[N];

Scanner input = new Scanner(System.in);

int i=0;

while(input.hasNextDouble()){

arr[i] =

i++;

}

System.out.println("Average [" + i + "] is "+ average(arr, i));

System.out.println("StdDev ["+ i + "] is "+ StdDev(arr, i));

}

else{

int N = args.length;

arr = new double[N];

try{

for(int i=0; i<N; i++)

arr[i] = Double.parseDouble(args[i]);

System.out.println("Average [" + N+ "] is "+ average(arr, N));

System.out.println("StdDev ["+N + "] is "+ StdDev(arr, N));

}

catch (Exception e) {

System.out.println("Usage: StdDev [n0 n1 n2...n]");

}

}

}

public static double average(double[] data, int size)

{

double total=0;

for (int i = 0; i < data.length; i++)

{

total+=data[i];

}

return total/data.length;

}

public static double StdDev(double[] data, int size)

{

double mean = average(data, N);

double t = 0;

for(double a :data)

t += (a-mean)*(a-mean);

double variance=t/size;

return Math.sqrt(variance);

}

public static double StdDev(double[] data, int size, double mean ){

double t = 0;

for(double a :data)

t += (a-mean)*(a-mean);

double variance=t/size;

return Math.sqrt(variance);

}

public static double[] doubleArraySize(double[] arr){

double[] newarr = new double[ arr.length * 2 ];

for(int i = 0; i<arr.length ; i++)

newarr[i] = arr[i];

return newarr;

}

}

Answer 1

Here is the code for you:

import java.util.Scanner;
public class StdDev {
static double[] arr;
static int N = 1;
public static void main(String[] args) {
if(args.length==0){
arr= new double[N];
Scanner input = new Scanner(System.in);
int i=0;
while(input.hasNextDouble()){
if(i >= N)
{
arr = doubleArraySize(arr);
N *= 2;
}
arr[i] = input.nextDouble();
i++;
}
System.out.println("Average [" + i + "] is "+ average(arr, i));
System.out.println("StdDev ["+ i + "] is "+ StdDev(arr, i));

}
else{
int N = args.length;
arr = new double[N];
try{
for(int i=0; i<N; i++)
arr[i] = Double.parseDouble(args[i]);
System.out.println("Average [" + N+ "] is "+ average(arr, N));
System.out.println("StdDev ["+N + "] is "+ StdDev(arr, N));
}
catch (Exception e) {
System.out.println("Usage: StdDev [n0 n1 n2...n]");
}
}
}

public static double average(double[] data, int size)
{
double total=0;
for (int i = 0; i <size; i++)
{
total+=data[i];
}
return total/size;
}

public static double StdDev(double[] data, int size)
{
double mean = average(data, size);

double t = 0;
for(int i = 0; i < size; i++)
t += (data[i]-mean)*(data[i]-mean);

double variance=t/size;

return Math.sqrt(variance);
}
public static double StdDev(double[] data, int size, double mean ){
double t = 0;
for(double a :data)
t += (a-mean)*(a-mean);

double variance=t/size;

return Math.sqrt(variance);
}

public static double[] doubleArraySize(double[] arr){
double[] newarr = new double[ arr.length * 2 ];

for(int i = 0; i<arr.length ; i++)
newarr[i] = arr[i];

return newarr;


}
}

And the output screenshot is: