P6-P15: init

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

P6.java

@@ -0,0 +1,20 @@
+import java.io.*;
+
+public class P6 {
+    public static void main(String[] args) throws IOException {
+        String filePath = "P6.in";
+
+        StringBuilder content = new StringBuilder();
+
+        try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
+            String line;
+            while ((line = reader.readLine()) != null) {
+                content.append(line.toUpperCase()).append("\n");
+            }
+        }
+
+        try (BufferedWriter writer = new BufferedWriter(new FileWriter(filePath))) {
+            writer.write(content.toString());
+        }
+    }
+}