Why do astronomers prefer to use the reflecting telescope rather than the refracting telescope to view distant objects in space?
2 answers:
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<h2>Answer:</h2>
//import the Scanner class to allow for user input
import java.util.Scanner;
//Begin class definition
public class FirstAndLast{
//Begin the main method
public static void main(String []args){
//****create an object of the Scanner class.
//Call the object 'input' to receive user's input
//from the console.
Scanner input = new Scanner(System.in);
//****create a prompt to tell the user what to do.
System.out.println("Enter the string");
//****receive the user's input
//And store it in a String variable called 'str'
String str = input.next();
//****get and print the first character.
//substring(0, 1) - means get all the characters starting
//from the lower bound (index 0) up to, but not including the upper
//bound(index 1).
//That technically means the first character.
System.out.print(str.substring(0,1));
//****get and print the last character
//1. str.length() will return the number of character in the string 'str'.
//This is also the length of the string
//2. substring(str.length() - 1) - means get all the characters starting
// from index that is one less than the length of the string to the last
// index (since an upper bound is not specified).
// This technically means the last character.
System.out.print(str.substring(str.length()-1));
} // end of main method
} //end of class definition
<h2>Explanation:</h2>The code has been written in Java and it contains comments explaining important parts of the code. Kindly go through the comments.
The source code and a sample output have also been attached to this response.
To run this program, copy the code in the source code inside a Java IDE or editor and save it as FirstAndLast.java
<span class="sg-text sg-text--link sg-text--bold sg-text--link-disabled sg-text--blue-dark">
java
</span>
Answer:
Following are the code to this question:
public class ArrayMath//defining a class ArrayMath
{
public static void main(String[] args) //defining main method
{
int x[][]=new int[10][10]; //defining a 2D array
arrays(x);//calling a method arrays by passing an array
}
private static void arrays(int[][] x)//defining a method arrays
{
int odd_column_sum=0,sum_of_Elements=0,i,j,even=1;//defining integer variable
for(i=0;i<x.length;i++)//defining loop for columns
{
for(j=0;j<x[0].length;j++)//defining loop for rows
{
x[i][j]=i*j;//multiply the i and j value atore in array
}
}
System.out.println("::The 2D array :: ");//print message
for(i=0;i<x.length;i++)//defining loop for columns
{
System.out.print("\t");//use print method for line space and line break
for(j=0;j<x[0].length;j++)//defining loop for rows
{
System.out.printf("%d\t",x[i][j]); //print array values
}
System.out.println( );//print for line break
}
for(i=0;i<x.length;i++) //defining loop for Columns
{
for(j=0;j<x[0].length;j++) //defining loop for rows
{
if(even%2!=0)//defining if block for check odd number condition
{
odd_column_sum+=x[j][i];//add odd number of array
}
sum_of_Elements+=x[i][j];//add even number of array
}
even++;//increment even variable value by 1
}
System.out.println("The sum of Odd Columns:"+odd_column_sum);//print odd_column_sum value
System.out.println("The array elements :"+sum_of_Elements);//print sum_of_Elements value
}
}
Output:
please find attached file.
Explanation:
In the above-given code, a class "ArrayMath" is defined, inside the class the main method is declared, which define a 2D array "x", this stores 10 columns and 10 rows and at the last, we call the arrays method by passing an array as a variable.
In the arrays method, integer variable, "odd_column_sum, sum_of_Elements, i, j, and even" is defined, in which variable "i and j" is used in the loop for calculating value, even is used to check odd column and then store its value in the "odd_column_sum" variable, and add whole element value is added into the "sum_of_Elements" variable.
