all the tests pass

src/main/java/rocks/zipcode/AlphaCharDocument.java

@@ -1,6 +1,7 @@
 package rocks.zipcode;
 
 import java.io.*;
+import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 /**
@@ -16,9 +17,15 @@ public class AlphaCharDocument extends Document {
 
     @Override
     public void write(String contentToBeWritten) throws IOException {
-        BufferedWriter writer = new BufferedWriter(new FileWriter("target/file.txt"));
-        writer.write(contentToBeWritten);
-        writer.close();
+
+        if (this.isAlpha(contentToBeWritten)){
+            super.write(contentToBeWritten);
+
+
+        }else{
+
+            throw  new  IllegalArgumentException();
+        }
 
     }
 
@@ -30,9 +37,12 @@ public class AlphaCharDocument extends Document {
 
 //        return (s.matches("[a-zA-Z]+"));
 
-        if(! Pattern.matches(".*[a-zA-Z]+.*", s))
-            return true;
-        else return false;
+        Pattern pattern = Pattern.compile("[a-z]", Pattern.CASE_INSENSITIVE);
+        Matcher matcher = pattern.matcher(s);
+        boolean b = matcher.find();
+        return b;
+
+
 
 
     }

src/main/java/rocks/zipcode/Document.java

@@ -6,6 +6,7 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Stream;
@@ -62,6 +63,7 @@ public class Document implements DocumentInterface {
 
     @Override
     public String read() {
+
         StringBuilder builder = new StringBuilder();
         try (BufferedReader br = new BufferedReader(new FileReader(file))) {
             String sCurrentLine;
@@ -104,17 +106,37 @@ public class Document implements DocumentInterface {
         }
     }
 
-    public List<String> toList() {
+    public List<String> toList() throws IOException {
+
         return null;
     }
 
+
     @Override
     public File getFile() {
-        return null;
+
+        return file;
     }
 
     @Override
     public String toString() {
-        return null;
-    }
+
+            String fileName = "target/file.txt";
+            String content = "";
+
+            try {
+                content = new String(Files.readAllBytes(Paths.get("target/file.txt")));
+
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+            StringBuilder builder = new StringBuilder(fileName)
+                    .append('{')
+                    .append(content)
+                    .append('}');
+
+
+            return builder.toString();
+        }
+
 }

src/main/java/rocks/zipcode/DocumentInterface.java

@@ -20,7 +20,7 @@ public interface DocumentInterface {
 
     void overWrite(String content);
 
-    List<String> toList();
+    List<String> toList() throws IOException;
 
     File getFile();
 

src/main/java/rocks/zipcode/NumericCharDocument.java

@@ -3,6 +3,7 @@ package rocks.zipcode;
 import java.io.BufferedWriter;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 /**
@@ -15,14 +16,24 @@ public class NumericCharDocument extends Document {
 
     @Override
     public void write(String contentToBeWritten) throws IOException {
-        BufferedWriter writer = new BufferedWriter(new FileWriter("target/file.txt"));
-        writer.write(contentToBeWritten);
-        writer.close();
+        if (this.isNumeric(contentToBeWritten)){
+            super.write(contentToBeWritten);
+
+
+        }else{
+            throw  new  IllegalArgumentException();
+        }
+
+
+
     }
 
     private Boolean isNumeric(String s) {
 
 
-        return false;
+        Pattern pattern = Pattern.compile("[0-9]", Pattern.CASE_INSENSITIVE);
+        Matcher matcher = pattern.matcher(s);
+        boolean b = matcher.find();
+        return b;
     }
 }

src/main/java/rocks/zipcode/SpecialCharDocument.java

@@ -3,6 +3,8 @@ package rocks.zipcode;
 import java.io.BufferedWriter;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  * @author leon on 18/11/2018.
@@ -14,13 +16,23 @@ public class SpecialCharDocument extends Document {
 
     @Override
     public void write(String contentToBeWritten) throws IOException {
-        BufferedWriter writer = new BufferedWriter(new FileWriter("target/file.txt"));
-        writer.write(contentToBeWritten);
-        writer.close();
+
+        if (this.isSpecialCharacters(contentToBeWritten)){
+            super.write(contentToBeWritten);
+
+
+        }else{
+
+            throw  new  IllegalArgumentException();
+        }
     }
 
     private Boolean isSpecialCharacters(String s) {
 
-        return null;
+        Pattern pattern = Pattern.compile("[$&+,:;=?@#|'<>.^*()%!-]", Pattern.CASE_INSENSITIVE);
+        Matcher matcher = pattern.matcher(s);
+        boolean b = matcher.find();
+        return b;
+
     }
 }