How To Find the Midpoint of a Line in Java?

Midpoint of a Line

The midpoint refers to a point that is exactly in the middle of the line segment, which is joined through two points. These are the endpoints of a line segment and the midpoint lying in between these two points.

The following diagram will provide a better understanding:

Midpoint Formula

The midpoint formula is defined for the points in the coordinate axes (i.e., x and y). Let's consider (x1, y1) and (x2, y2) are the endpoints of a line segment. The midpoint will be equal to half of the sum of the x-coordinates of the two points and half of the sum of the y-coordinates of the two points.

Use the following formula to find the midpoint of the a line:

Midpoint of line = ((x1 + x2)/2 , (y1 + y2)/2)

Here, the points x1 and x2 are located on the x-axis, while points y1 and y2 are located on the y-axis.

Input & Output Scenarios

Following are the few input and output scenario that helps you to understand how to find the midpoint of a line by doing mathematical calculations:

Scenario 1

Suppose the two points on the line are (2,3) and (3,5):

Input: pintA = (2, 3), pointB = (3, 5)
Output:midPoint = (2.5, 4.0)

Calculation:
ma = (x1 + x2)/2 = (2 + 3)/2 = 2.5
mb = (y1 + y2)/2 = (3 + 5)/2 = 4.0

The midpoint of line is (2.5, 4.0).

Scenario 2

Suppose the two points on the line are (2, -3) and (-3, 5):

Input: pointA = (2, -3), pointB = (-3, 5)
Output: midPoint = (-0.5, 1.0)

Calculation:
ma = (x1 + x2)/2 = (2 + (-3)/2 = -0.5
mb = (y1 + y2)/2 = ((-3) + 5)/2 = 1.0

The midpoint of line is (-0.5, 1.0).

Let's implement the above scenarios in the Java program to find the midpoint of the given points:

Example 1: Midpoint of the Negative Coordinates

In the example below, we use the above formula to find the midpoint on the drawn line by using the given points (-2, -2) and (4, 3):

Diagram:

The diagram below drawn a line according to the specified points, and also mentioned the midpoint:

Program:

public class Line{
   public static void main(String[] args){
      double x1 = -2;
      double y1 = -2;
      double x2 = 4;
      double y2 = 3;
      System.out.println("The give points are: ");
      System.err.println("(x1 = " + x1 + ", y1 = " + y1 + ") and " + "(x2 = " + x2 + ", y2 = " + y2 + ")");
      
      //find the midpoint of given points
      double x = (x1 + x2) / 2;
      double y=(y1 + y2) / 2;
      System.out.println("The mid point = (" + x + " , " + y + ")");
   }   
}

Output

The above program produces the following output:

The give points are: 
(x1 = -2.0, y1 = -2.0) and (x2 = 4.0, y2 = 3.0)
The mid point = (1.0 , 0.5)

Example 2: Midpoint of the Positive Coordinates

In the example below, we define a method named findMidpoint(), which uses the ((x1+x2)/2, (y1+y2)/2) formula to calculate the midpoint on the line by using the given points (1, 1) and (4, 3):

Diagram:

In the diagram below, the line is drawn according to the specified points, and the midpoint is also mentioned:

Program:

public class Line {
   
   //user defined method
   public static void findMidpoint(double x1, double y1, double x2, double y2){
      //fint the midpoint 
      double x = (x1 + x2) / 2;
      double y = (y1 + y2) / 2;
      System.out.println("The mid point = (" + x + " , " + y + ")");
   }
   public static void main(String[] args){
      double x1 = 1;
      double y1 = 1;
      double x2 = 4;
      double y2 = 3;
      
      System.out.println("The give points are: ");
      System.err.println("(x1 = " + x1 + ", y1 = " + y1 + ") and " + "(x2 = " + x2 + ", y2 = " + y2 + ")");
      //calling the findMidpoint() method to find the midpoint
      findMidpoint(x1, y1, x2, y2);
   }
}

Output

Following is the output of the above program:

The give points are: 
(1.0, 1.0) and (4.0, 3.0)
The mid point = (2.5 , 2.0)