diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..549e00a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,33 @@
+HELP.md
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
diff --git a/pom.xml b/pom.xml
new file mode 100644
index 0000000..1d22473
--- /dev/null
+++ b/pom.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>se.nackademin.java20</groupId>
+    <artifactId>solid</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.5.1</version>
+                <configuration>
+                    <source>11</source>
+                    <target>11</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>
\ No newline at end of file
diff --git a/src/main/java/se/nackademin/java20/solid/_1sre/violation/Account.java b/src/main/java/se/nackademin/java20/solid/_1sre/violation/Account.java
new file mode 100644
index 0000000..c8bf9d0
--- /dev/null
+++ b/src/main/java/se/nackademin/java20/solid/_1sre/violation/Account.java
@@ -0,0 +1,17 @@
+package se.nackademin.java20.solid._1sre.violation;
+
+public class Account {
+    private int balance;
+
+    public Account(int balance) {
+        this.balance = balance;
+    }
+
+    public void deposit(int money) {
+        this.balance += money;
+    }
+
+    public void print() {
+        System.out.println("Current balance: " + balance);
+    }
+}
diff --git a/src/main/java/se/nackademin/java20/solid/_2ocp/violation/Validator.java b/src/main/java/se/nackademin/java20/solid/_2ocp/violation/Validator.java
new file mode 100644
index 0000000..10f7a65
--- /dev/null
+++ b/src/main/java/se/nackademin/java20/solid/_2ocp/violation/Validator.java
@@ -0,0 +1,11 @@
+package se.nackademin.java20.solid._2ocp.violation;
+
+public class Validator {
+
+    public boolean validate(int quantity) {
+        if (quantity < 0) return false;
+        if (quantity > 100) return false;
+        return true;
+    }
+
+}
diff --git a/src/main/java/se/nackademin/java20/solid/_3lsp/violation/Rectangle.java b/src/main/java/se/nackademin/java20/solid/_3lsp/violation/Rectangle.java
new file mode 100644
index 0000000..33a0f5b
--- /dev/null
+++ b/src/main/java/se/nackademin/java20/solid/_3lsp/violation/Rectangle.java
@@ -0,0 +1,23 @@
+package se.nackademin.java20.solid._3lsp.violation;
+
+public class Rectangle {
+    private int width;
+    private int height;
+
+    public Rectangle(int width, int height) {
+        this.width = width;
+        this.height = height;
+    }
+
+    public void setWidth(int width) {
+        this.width = width;
+    }
+
+    public void setHeight(int height) {
+        this.height = height;
+    }
+
+    public int area() {
+        return width * height;
+    }
+}
diff --git a/src/main/java/se/nackademin/java20/solid/_3lsp/violation/Square.java b/src/main/java/se/nackademin/java20/solid/_3lsp/violation/Square.java
new file mode 100644
index 0000000..a458deb
--- /dev/null
+++ b/src/main/java/se/nackademin/java20/solid/_3lsp/violation/Square.java
@@ -0,0 +1,20 @@
+package se.nackademin.java20.solid._3lsp.violation;
+
+public class Square extends Rectangle {
+    public Square(int width, int height) {
+        super(width, height);
+    }
+
+    @Override
+    public void setWidth(int width) {
+        super.setWidth(width);
+        super.setHeight(width);
+    }
+
+    @Override
+    public void setHeight(int height) {
+        super.setHeight(height);
+        super.setWidth(height);
+    }
+
+}
diff --git a/src/main/java/se/nackademin/java20/solid/_4isp/violation/Animal.java b/src/main/java/se/nackademin/java20/solid/_4isp/violation/Animal.java
new file mode 100644
index 0000000..ebe1974
--- /dev/null
+++ b/src/main/java/se/nackademin/java20/solid/_4isp/violation/Animal.java
@@ -0,0 +1,6 @@
+package se.nackademin.java20.solid._4isp.violation;
+
+public interface Animal {
+    void run();
+    void jump();
+}
diff --git a/src/main/java/se/nackademin/java20/solid/_4isp/violation/Elephant.java b/src/main/java/se/nackademin/java20/solid/_4isp/violation/Elephant.java
new file mode 100644
index 0000000..c89505b
--- /dev/null
+++ b/src/main/java/se/nackademin/java20/solid/_4isp/violation/Elephant.java
@@ -0,0 +1,14 @@
+package se.nackademin.java20.solid._4isp.violation;
+
+public class Elephant implements Animal {
+    @Override
+    public void run() {
+        System.out.println("I am running super fast!");
+    }
+
+    @Override
+    public void jump() {
+        throw new UnsupportedOperationException("I cannot jump!");
+
+    }
+}
diff --git a/src/main/java/se/nackademin/java20/solid/_4isp/violation/Tiger.java b/src/main/java/se/nackademin/java20/solid/_4isp/violation/Tiger.java
new file mode 100644
index 0000000..b6efbcc
--- /dev/null
+++ b/src/main/java/se/nackademin/java20/solid/_4isp/violation/Tiger.java
@@ -0,0 +1,14 @@
+package se.nackademin.java20.solid._4isp.violation;
+
+public class Tiger implements Animal {
+    @Override
+    public void run() {
+        System.out.println("Like the speed of light!");
+    }
+
+    @Override
+    public void jump() {
+        System.out.println("Jumping highest of them all!");
+
+    }
+}
diff --git a/src/main/java/se/nackademin/java20/solid/_5dip/violation/ConsolePrinter.java b/src/main/java/se/nackademin/java20/solid/_5dip/violation/ConsolePrinter.java
new file mode 100644
index 0000000..5b944a5
--- /dev/null
+++ b/src/main/java/se/nackademin/java20/solid/_5dip/violation/ConsolePrinter.java
@@ -0,0 +1,7 @@
+package se.nackademin.java20.solid._5dip.violation;
+
+public class ConsolePrinter {
+    void print(String text) {
+        System.out.println(text);
+    }
+}
diff --git a/src/main/java/se/nackademin/java20/solid/_5dip/violation/TextPrinter.java b/src/main/java/se/nackademin/java20/solid/_5dip/violation/TextPrinter.java
new file mode 100644
index 0000000..104afe1
--- /dev/null
+++ b/src/main/java/se/nackademin/java20/solid/_5dip/violation/TextPrinter.java
@@ -0,0 +1,13 @@
+package se.nackademin.java20.solid._5dip.violation;
+
+public class TextPrinter {
+    private final ConsolePrinter consolePrinter;
+
+    public TextPrinter(ConsolePrinter consolePrinter) {
+        this.consolePrinter = consolePrinter;
+    }
+
+    public void print(String text) {
+        consolePrinter.print(text);
+    }
+}