# Java Program to Find the Position of a Point with Respect to a Line using Above-Below-on Test

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This is a Java Program to check whether a point lies below, above or on the line. For any point t (xt, yt) on the plane, its position with respect to the line L connecting p and q is found by calculating the scalar s:
s = A xt + B yt + C
If s < 0, t lies in the clockwise halfplane of L; if s > 0, t lies on the counter-clockwise halfplane; if s = 0, t lies on L.
For example, the equation of the line connecting points (2, 2) and (4, 5) is -3x + 2y + 2 = 0. The point (6, 3) lies in the clockwise halfplane of this line, because (-3)(6) + (2)(3) + 2 = -10. Conversely, the point (0, 5) lies in the other halfplane as (-3)(0) +(2)(5) +2 = 12.

Here is the source code of the Java Program to Apply Above-Below-on Test to Find the Position of a Point with respect to a Line. The Java program is successfully compiled and run on a Windows system. The program output is also shown below.

1. `//This is a java program to check whether a point lies on, above or below the gievn line`
2. `import java.util.Random;`
3. `import java.util.Scanner;`
4. ` `
5. `public class Position_Point_WRT_Line`
6. `{`
7. `    public static void main(String args[])`
8. `    {`
9. `        Random random = new Random();`
10. `        int x1, x2, y1, y2;`
11. `        x1 = random.nextInt(10);`
12. `        x2 = random.nextInt(10);`
13. `        y1 = random.nextInt(10);`
14. `        y2 = random.nextInt(10);`
15. ` `
16. `        System.out.println("The Equation of the line is : (" + (y2 - y1)`
17. `                + ")x+(" + (x1 - x2) + ")y+(" + (x2 * y1 - x1 * y2) + ") = 0");`
18. ` `
19. `        System.out.println("Enter the point : <x>,<y>");`
20. `        Scanner scan = new Scanner(System.in);`
21. `        int x, y;`
22. `        x = scan.nextInt();`
23. `        y = scan.nextInt();`
24. ` `
25. `        int s = (y2 - y1) * x + (x1 - x2) * y + (x2 * y1 - x1 * y2);`
26. `        if (s < 0)`
27. `            System.out`
28. `                    .println("The point lies below the line or left side of the line");`
29. `        else if (s > 0)`
30. `            System.out`
31. `                    .println("The point lies above the line or right side of the line");`
32. `        else`
33. `            System.out.println("The point lies on the line");`
34. `        scan.close();`
35. `    }`
36. `}`

Output:

```\$ javac Position_Point_WRT_Line.java
\$ java Position_Point_WRT_Line

The Equation of the line is : (-2)x+(-9)y+(81) = 0
Enter the point : <x>,<y>
2
3
The point lies above the line or right side of the line```

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