diff --git a/README.md b/README.md
index bb37572..5ce862f 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,8 @@
 - [] Emacs Lisp
 - [x] Haskell
   - [Day 7](./day-07)
-- [] Java
+- [x] Java
+  - [Day 13](./day-13)
 - [x] JavaScript
   - [Day 6](./day-06)
 - [] Kotlin
diff --git a/day-13/sol.java b/day-13/sol.java
new file mode 100644
index 0000000..7613dcd
--- /dev/null
+++ b/day-13/sol.java
@@ -0,0 +1,147 @@
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.Scanner;
+import java.awt.Point;
+import java.util.Set;
+
+public class sol {
+  enum PROBLEM {
+    PROBLEM_1, PROBLEM_2
+  }
+
+  class Grid {
+    private Set<Point> sand;
+    private Set<Point> filled;
+    private Point source;
+    private int maxYP2;
+
+    public Grid(Point source, ArrayList<ArrayList<Point>> paths) {
+      this.sand = new HashSet<Point>();
+      this.filled = new HashSet<Point>();
+      this.source = source;
+
+      for (ArrayList<Point> path : paths)
+        for (int i = 1; i < path.size(); i++) {
+          Point p1 = path.get(i - 1);
+          Point p2 = path.get(i);
+          for (int x = Math.min(p1.x, p2.x); x <= Math.max(p1.x, p2.x); x++)
+            for (int y = Math.min(p1.y, p2.y); y <= Math.max(p1.y, p2.y); y++)
+              this.filled.add(new Point(x, y));
+        }
+
+      maxYP2 = bottomRight().y + 1;
+    }
+
+    public boolean addSandGrain(PROBLEM problem) {
+      Point p = new Point(this.source.x, this.source.y);
+      while (true) {
+        if (this.filled.contains(p) || (problem == PROBLEM.PROBLEM_2 && p.y >= maxYP2)) {
+          if (problem == PROBLEM.PROBLEM_2 && p.x == this.source.x && p.y == this.source.y)
+            return false;
+
+          p.y--;
+          filled.add(p);
+          sand.add(p);
+          return true;
+        }
+
+        if (problem == PROBLEM.PROBLEM_1 && p.y >= bottomRight().y)
+          return false;
+
+        p.y++;
+        if (this.filled.contains(new Point(p.x, p.y))) {
+          if (!this.filled.contains(new Point(p.x - 1, p.y)))
+            p.x--;
+          else if (!this.filled.contains(new Point(p.x + 1, p.y)))
+            p.x++;
+        }
+      }
+    }
+
+    public Point topLeft() {
+      return new Point(
+          filled.stream().min((p1, p2) -> p1.x - p2.x).get().x,
+          filled.stream().min((p1, p2) -> p1.y - p2.y).get().y);
+    }
+
+    public Point bottomRight() {
+      return new Point(
+          filled.stream().max((p1, p2) -> p1.x - p2.x).get().x,
+          filled.stream().max((p1, p2) -> p1.y - p2.y).get().y);
+    }
+
+    public void print() {
+      Point topLeft = topLeft();
+      Point bottomRight = bottomRight();
+
+      Point curr = new Point(topLeft.x, topLeft.y);
+      for (; curr.y <= bottomRight.y; curr.y++) {
+        for (; curr.x <= bottomRight.x; curr.x++) {
+          if (sand.contains(curr))
+            System.out.print("o");
+          else if (filled.contains(curr))
+            System.out.print("#");
+          else
+            System.out.print(".");
+        }
+        curr.x = topLeft.x;
+        System.out.println();
+      }
+    }
+  }
+
+  public static ArrayList<ArrayList<Point>> parsePaths(ArrayList<String> inputList) {
+    ArrayList<ArrayList<Point>> paths = new ArrayList<ArrayList<Point>>();
+    for (String line : inputList) {
+      ArrayList<Point> path = new ArrayList<Point>();
+
+      String[] points = line.split(" -> ");
+      for (String point : points) {
+        String[] coords = point.split(",");
+        path.add(new Point(Integer.parseInt(coords[0]), Integer.parseInt(coords[1])));
+      }
+
+      paths.add(path);
+    }
+    return paths;
+  }
+
+  public static ArrayList<String> getInputLines(String file) {
+    ArrayList<String> inputList = new ArrayList<String>();
+
+    try {
+      File input = new File(file);
+      Scanner sc = new Scanner(input);
+
+      while (sc.hasNextLine())
+        inputList.add(sc.nextLine());
+
+      sc.close();
+    } catch (FileNotFoundException e) {
+      e.printStackTrace();
+    }
+
+    return inputList;
+  }
+
+  public static void main(String[] args) {
+    ArrayList<ArrayList<Point>> paths = parsePaths(getInputLines("input"));
+
+    sol s = new sol();
+    Grid gridP1 = s.new Grid(new Point(500, 0), paths);
+    int i = 0;
+    for (; gridP1.addSandGrain(PROBLEM.PROBLEM_1); i++) {
+      // gridP1.print();
+    }
+    System.out.println(i);
+
+    Grid gridP2 = s.new Grid(new Point(500, 0), paths);
+    i = 0;
+    for (; gridP2.addSandGrain(PROBLEM.PROBLEM_2); i++) {
+      // gridP2.print();
+    }
+    System.out.println(i);
+  }
+}
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