diff --git a/src/main/java/nl/sander/beejava/Compiler.java b/src/main/java/nl/sander/beejava/Compiler.java
index 029b94b..d47c6c2 100644
--- a/src/main/java/nl/sander/beejava/Compiler.java
+++ b/src/main/java/nl/sander/beejava/Compiler.java
@@ -34,6 +34,7 @@ public class Compiler {
 
     CompiledClass compile() {
         compiledClass.getBeeClass().getConstructors().forEach(this::updateConstantPool);
+        compiledClass.getBeeClass().getMethods().forEach(this::updateConstantPool);
         // TODO update constant pool for fields ?
         // TODO update constant pool for methods
 
@@ -45,7 +46,7 @@ public class Compiler {
     }
 
 
-    private void updateConstantPool(ContainsCode codeContainer) {
+    private void updateConstantPool(CodeContainer codeContainer) {
         codeContainer.getCode().forEach(this::updateConstantPool);
     }
 
@@ -59,12 +60,16 @@ public class Compiler {
      *      So Compiled class also contains a set of unique root nodes.
      */
     private void updateConstantPool(CodeLine codeline) {
-        if (codeline.hasMethod()) {
+        if (codeline.hasMethodCall()) {
             compiledClass.addConstantPoolEntry(constantPoolEntryCreator.getOrCreateMethodRefEntry(codeline));
         }
 
-        if (codeline.hasField()) {
+        if (codeline.hasRefToOwnField() || codeline.hasRefToExternalField()) {
             compiledClass.addConstantPoolEntry(constantPoolEntryCreator.getOrCreateFieldRefEntry(codeline));
         }
+
+        if (codeline.hasConstValue()) {
+            compiledClass.addConstantPoolEntry(constantPoolEntryCreator.getOrCreatePrimitiveEntry(codeline));
+        }
     }
 }
diff --git a/src/main/java/nl/sander/beejava/ConstantPoolEntryCreator.java b/src/main/java/nl/sander/beejava/ConstantPoolEntryCreator.java
index 7339ed3..ece8fdf 100644
--- a/src/main/java/nl/sander/beejava/ConstantPoolEntryCreator.java
+++ b/src/main/java/nl/sander/beejava/ConstantPoolEntryCreator.java
@@ -1,6 +1,5 @@
 package nl.sander.beejava;
 
-import nl.sander.beejava.api.BeeClass;
 import nl.sander.beejava.api.CodeLine;
 import nl.sander.beejava.api.Ref;
 import nl.sander.beejava.constantpool.entry.*;
@@ -31,7 +30,16 @@ class ConstantPoolEntryCreator {
     }
 
     private NameAndTypeEntry createFieldNameAndType(CodeLine codeline) {
-        return cache(new NameAndTypeEntry(cache(new Utf8Entry(codeline.getField().getName())), cache(new Utf8Entry(TypeMapper.map(codeline.getField().getType())))));
+        if (codeline.hasRefToOwnField()) {
+            return cache(new NameAndTypeEntry(
+                    cache(new Utf8Entry(codeline.getOwnfield().getName())),
+                    cache(new Utf8Entry(TypeMapper.map(codeline.getOwnfield().getType()))))); // is actually a shortcut
+        } else {
+            return cache(new NameAndTypeEntry(
+                    cache(new Utf8Entry(codeline.getExternalfield())),
+                    cache(new Utf8Entry("L" + codeline.getExternalfieldClass()))
+            ));
+        }
     }
 
     private NameAndTypeEntry getOrCreateMethodNameAndType(CodeLine codeline) {
@@ -41,21 +49,26 @@ class ConstantPoolEntryCreator {
     }
 
     private ClassEntry getOrCreateClassEntry(CodeLine codeline) {
-        if (codeline.getRef() == Ref.SUPER) { //this and super are rather special
-            ClassEntry superClass = getClassEntry(compiledClass.getBeeClass().getSuperClass().getName());
-            compiledClass.setSuperClass(superClass);
-            return superClass;
+        if (codeline.hasRef()) {
+            if (codeline.getRef() == Ref.SUPER) { //this and super are rather special
+                ClassEntry superClass = getClassEntry(compiledClass.getBeeClass().getSuperClass().getName());
+                compiledClass.setSuperClass(superClass);
+                return superClass;
 
-        } else if (codeline.getRef() == Ref.THIS) {
-            addThisClass();
-            return compiledClass.getThisClass();
+            } else if (codeline.getRef() == Ref.THIS) {
+                addThisClass();
+                return compiledClass.getThisClass();
+            }
+        } else if (codeline.hasClassName()) {
+            return getClassEntry(codeline.getClassName());
         }
-        //TODO other cases
+
         throw new RuntimeException("shouldn't be here");
     }
 
-    void addThisClass(){
+    void addThisClass() {
         ClassEntry classEntry = getClassEntry(compiledClass.getBeeClass().getName());
+        compiledClass.addConstantPoolEntry(classEntry);
         compiledClass.setThisClass(classEntry);
     }
 
@@ -71,7 +84,22 @@ class ConstantPoolEntryCreator {
         });
     }
 
+    public ConstantPoolEntry getOrCreatePrimitiveEntry(CodeLine codeline) {
+        Object v = codeline.getConstValue();
 
+        if (v instanceof String) {
+            return cache(new StringEntry(cache(new Utf8Entry((String) v))));
+        } else if (v instanceof Integer) {
+            return cache(new IntegerEntry((Integer) v));
+        } else if (v instanceof Long) {
+            return cache(new LongEntry((Long) v));
+        } else if (v instanceof Float) {
+            return cache(new FloatEntry((Float) v));
+        } else if (v instanceof Double) {
+            return cache(new DoubleEntry((Double) v));
+        }
+        throw new RuntimeException(); // TODO find out why are you here
+    }
 
     public void addFields() {
         compiledClass.getBeeClass().getFields().forEach(field -> {
@@ -88,9 +116,11 @@ class ConstantPoolEntryCreator {
         // First create an object using the supplier, but if it's found in cache, return the cached entry and discard the first.
         // Can't check for equality unless you create a potential new entry first
         int hash = newEntry.hashCode();
-        return (T) cache.computeIfAbsent(hash, k -> newEntry);
+        T a = (T) cache.computeIfAbsent(hash, k -> newEntry);
+        return a;
         // a hashmap with key hash of value is weird right?
         // A HashSet is a HashMap with entry: key = value, which would work, but I cannot _get_ anything from a set.
     }
 
+
 }
diff --git a/src/main/java/nl/sander/beejava/api/BeeClass.java b/src/main/java/nl/sander/beejava/api/BeeClass.java
index ec2f161..d4877b9 100644
--- a/src/main/java/nl/sander/beejava/api/BeeClass.java
+++ b/src/main/java/nl/sander/beejava/api/BeeClass.java
@@ -2,6 +2,7 @@ package nl.sander.beejava.api;
 
 import nl.sander.beejava.flags.ClassAccessFlag;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Set;
@@ -15,10 +16,11 @@ public class BeeClass {
     private final Set<Class<?>> interfaces = new HashSet<>();
     private final Set<BeeField> fields = new HashSet<>();
     private final Set<BeeConstructor> constructors = new HashSet<>();
+    private final Set<BeeMethod> methods = new HashSet<>();
 
     private BeeClass(Version classFileVersion,
                      BeePackage beePackage, Set<ClassAccessFlag> accessFlags, String simpleName, Class<?> superClass,
-                     Set<Class<?>> interfaces, Set<BeeField> fields, Set<BeeConstructor> constructors) {
+                     Set<Class<?>> interfaces, Set<BeeField> fields, Set<BeeConstructor> constructors, Set<BeeMethod> methods) {
         this.classFileVersion = classFileVersion;
         this.beePackage = beePackage;
         this.accessFlags.addAll(accessFlags);
@@ -27,6 +29,7 @@ public class BeeClass {
         this.interfaces.addAll(interfaces);
         this.fields.addAll(fields);
         this.constructors.addAll(constructors);
+        this.methods.addAll(methods);
     }
 
     public static BeeClass.Builder builder() {
@@ -52,6 +55,10 @@ public class BeeClass {
         return constructors;
     }
 
+    public Set<BeeMethod> getMethods() {
+        return methods;
+    }
+
     public Set<ClassAccessFlag> getAccessFlags() {
         return accessFlags;
     }
@@ -79,11 +86,12 @@ public class BeeClass {
         private final Set<ClassAccessFlag> accessFlags = new HashSet<>();
         private final Set<Class<?>> interfaces = new HashSet<>();
         private final Set<BeeField> fields = new HashSet<>();
-        private final Set<BeeConstructor> constructors = new HashSet<>();
         private Version version;
         private BeePackage beePackage;
         private Class<?> superClass = Object.class;
         private String simpleName;
+        private final Set<BeeConstructor> constructors = new HashSet<>();
+        private final Set<BeeMethod> methods = new HashSet<>();
 
         private Builder() {
         }
@@ -128,10 +136,14 @@ public class BeeClass {
             return this;
         }
 
-        public BeeClass build() {
-            return new BeeClass(version, beePackage, accessFlags, simpleName, superClass, interfaces, fields, constructors);
+        public Builder withMethods(BeeMethod... methods) {
+            this.methods.addAll(Arrays.asList(methods));
+            return this;
         }
 
+        public BeeClass build() {
+            return new BeeClass(version, beePackage, accessFlags, simpleName, superClass, interfaces, fields, constructors, methods);
+        }
 
     }
 }
diff --git a/src/main/java/nl/sander/beejava/api/BeeConstructor.java b/src/main/java/nl/sander/beejava/api/BeeConstructor.java
index f5d7643..a28355f 100644
--- a/src/main/java/nl/sander/beejava/api/BeeConstructor.java
+++ b/src/main/java/nl/sander/beejava/api/BeeConstructor.java
@@ -1,6 +1,6 @@
 package nl.sander.beejava.api;
 
-import nl.sander.beejava.ContainsCode;
+import nl.sander.beejava.CodeContainer;
 import nl.sander.beejava.flags.MethodAccessFlag;
 
 import java.util.*;
@@ -8,17 +8,16 @@ import java.util.*;
 /**
  * Models a constructor
  */
-public class BeeConstructor implements ContainsCode {
+public class BeeConstructor extends CodeContainer {
     private final Set<MethodAccessFlag> accessFlags = new HashSet<>();
     private final Set<BeeParameter> formalParameters = new HashSet<>();
-    private final List<CodeLine> code = new LinkedList<>();
 
     private BeeConstructor(Set<MethodAccessFlag> accessFlags,
                            List<BeeParameter> formalParameters,
                            List<CodeLine> code) {
         this.formalParameters.addAll(formalParameters);
         this.accessFlags.addAll(accessFlags);
-        this.code.addAll(code);
+        super.code.addAll(code);
     }
 
     public static Builder builder() {
@@ -33,11 +32,6 @@ public class BeeConstructor implements ContainsCode {
         return formalParameters;
     }
 
-    @Override
-    public List<CodeLine> getCode() {
-        return code;
-    }
-
     @Override
     public String toString() {
         return "BeeConstructor{" +
diff --git a/src/main/java/nl/sander/beejava/api/BeeMethod.java b/src/main/java/nl/sander/beejava/api/BeeMethod.java
new file mode 100644
index 0000000..400fd66
--- /dev/null
+++ b/src/main/java/nl/sander/beejava/api/BeeMethod.java
@@ -0,0 +1,59 @@
+package nl.sander.beejava.api;
+
+import nl.sander.beejava.CodeContainer;
+import nl.sander.beejava.flags.MethodAccessFlag;
+
+import java.util.*;
+
+public final class BeeMethod extends CodeContainer {
+    private final Set<MethodAccessFlag> accessFlags = new HashSet<>();
+    private final Set<BeeParameter> formalParameters = new HashSet<>();
+    private final Class<?> returnType;
+
+    private BeeMethod(Set<MethodAccessFlag> accessFlags,
+                      List<BeeParameter> formalParameters,
+                      Class<?> returnType, List<CodeLine> code) {
+        this.accessFlags.addAll(accessFlags);
+        this.formalParameters.addAll(formalParameters);
+        this.returnType = returnType;
+        super.code.addAll(code);
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder {
+        private final Set<MethodAccessFlag> accessFlags = new HashSet<>();
+        private final List<BeeParameter> formalParameters = new LinkedList<>();
+        private final List<CodeLine> code = new LinkedList<>();
+        private Class<?> returnType;
+
+        private Builder() {
+        }
+
+        public Builder withAccessFlags(MethodAccessFlag... accessFlags) {
+            this.accessFlags.addAll(Arrays.asList(accessFlags));
+            return this;
+        }
+
+        public Builder withFormalParameters(BeeParameter... formalParameters) {
+            this.formalParameters.addAll(Arrays.asList(formalParameters));
+            return this;
+        }
+
+        public Builder withReturnType(Class<?> returnType) {
+            this.returnType = returnType;
+            return this;
+        }
+
+        public Builder withCode(CodeLine... lines) {
+            this.code.addAll(Arrays.asList(lines));
+            return this;
+        }
+
+        public BeeMethod build() {
+            return new BeeMethod(accessFlags, formalParameters, returnType, code);
+        }
+    }
+}
diff --git a/src/main/java/nl/sander/beejava/api/CodeLine.java b/src/main/java/nl/sander/beejava/api/CodeLine.java
index 92fcb88..ca83150 100644
--- a/src/main/java/nl/sander/beejava/api/CodeLine.java
+++ b/src/main/java/nl/sander/beejava/api/CodeLine.java
@@ -6,10 +6,15 @@ public class CodeLine {
     private final Opcode opcode;
     private Ref ref;
     private BeeParameter parameter;
+    private String className;
     private String methodName;
     private String inputSignature;
     private String outputSignature;
-    private BeeField field;
+    private BeeField ownfield; // when you create a class with a field, you can refer to it
+    private String externalfield; // when you refer to a field from another class
+
+    private Object constValue;
+    private String externalFieldType;
 
     CodeLine(int linenumber, Opcode opcode) {
         this.linenumber = linenumber;
@@ -20,6 +25,18 @@ public class CodeLine {
         return new CodeLine(nr, opcode).withRef(ref);
     }
 
+    public static CodeLine line(int nr, Opcode opcode, String fieldClass, String fieldName) {
+        return new CodeLine(nr, opcode).withExternalFieldRef(fieldClass, fieldName);
+    }
+
+    public static CodeLine line(int nr, Opcode opcode, Object constValue) {
+        return new CodeLine(nr, opcode).withConstValue(constValue);
+    }
+
+    public static CodeLine line(int nr, Opcode opcode, String className, String methodName, String inputSignature) {
+        return new CodeLine(nr, opcode).withClassName(className).withMethodName(methodName).withInput(inputSignature).withVoidOutput();
+    }
+
     public static CodeLine line(int nr, Opcode opcode, Ref ref, String methodNameRef, String inputSignature) {
         return new CodeLine(nr, opcode).withRef(ref).withMethodName(methodNameRef).withInput(inputSignature).withVoidOutput();
     }
@@ -37,7 +54,7 @@ public class CodeLine {
     }
 
     public static CodeLine line(int nr, Opcode opcode, BeeField intField) {
-        return new CodeLine(nr, opcode).withRef(Ref.THIS).withField(intField);
+        return new CodeLine(nr, opcode).withRef(Ref.THIS).withOwnField(intField);
     }
 
     private CodeLine withRef(Ref ref) {
@@ -45,6 +62,11 @@ public class CodeLine {
         return this;
     }
 
+    private CodeLine withClassName(String className) {
+        this.className = className;
+        return this;
+    }
+
     private CodeLine withMethodName(String methodName) {
         this.methodName = methodName;
         return this;
@@ -69,16 +91,57 @@ public class CodeLine {
         return this;
     }
 
-    private CodeLine withField(BeeField field) {
-        this.field = field;
+    private CodeLine withConstValue(Object constValue) {
+        this.constValue = constValue;
+        return this; //TODO
+    }
+
+    private CodeLine withOwnField(BeeField beeField) {
+        this.ownfield = beeField;
         return this;
     }
 
+    private CodeLine withExternalFieldRef(String className, String field) {
+        this.className = className;
+        this.externalFieldType = getType(className, field);
+        this.externalfield = field;
+        return this;
+
+    }
+
+    // TODO decide whether to work with Strings or class objects...
+
+    /*
+     * Look up the type of a field in a class
+     *
+     * Assumes field is accessible
+     *
+     * @param className the class containing a field
+     * @param field name of the field
+     * @return the  field type
+     */
+    private String getType(String className, String field) {
+        try {
+            return Class.forName(className).getField(field).getType().getName();
+        } catch (ClassNotFoundException | NoSuchFieldException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public boolean hasClassName() {
+        return className != null;
+    }
+
+
+    public String getClassName() {
+        return className;
+    }
+
     public String getMethodName() {
         return methodName;
     }
 
-    public boolean hasMethod() {
+    public boolean hasMethodCall() {
         return methodName != null;
     }
 
@@ -94,12 +157,21 @@ public class CodeLine {
         return ref != null;
     }
 
-    public boolean hasField() {
-        return field != null;
+    public boolean hasRefToOwnField() {
+        return ownfield != null;
     }
 
-    public BeeField getField() {
-        return field;
+
+    public Object getConstValue() {
+        return constValue;
+    }
+
+    public boolean hasConstValue() {
+        return constValue != null;
+    }
+
+    public BeeField getOwnfield() {
+        return ownfield;
     }
 
     public BeeParameter getParameter() {
@@ -107,4 +179,15 @@ public class CodeLine {
     }
 
 
+    public boolean hasRefToExternalField() {
+        return externalfield != null;
+    }
+
+    public String getExternalfield() {
+        return externalfield;
+    }
+
+    public String getExternalfieldClass() {
+        return externalFieldType;
+    }
 }
diff --git a/src/test/java/nl/sander/beejava/testclasses/BeanWithClassReferences.java b/src/test/java/nl/sander/beejava/testclasses/BeanWithClassReferences.java
index 554872d..7e816e6 100644
--- a/src/test/java/nl/sander/beejava/testclasses/BeanWithClassReferences.java
+++ b/src/test/java/nl/sander/beejava/testclasses/BeanWithClassReferences.java
@@ -1,12 +1,19 @@
 package nl.sander.beejava.testclasses;
 
+// two references to System. System should not be in the constant pool twice.
 public class BeanWithClassReferences {
 
-    public void print1(){
+    public void print1() {
         System.out.println("1");
     }
 
-    public void print2(){
-        System.out.println("2");
+    public void print2() {
+        System.out.println(create2());
+    }
+
+    public String create2() {
+        StringBuilder stringBuilder = new StringBuilder();
+        stringBuilder.append("2");
+        return stringBuilder.toString();
     }
 }