Exo 1 TP2

.idea/compiler.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="CompilerConfiguration">
-    <bytecodeTargetLevel target="1.8" />
+    <bytecodeTargetLevel target="15" />
   </component>
 </project>
\ No newline at end of file

.idea/misc.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" project-jdk-name="11" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_15" project-jdk-name="corretto-15" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/out" />
   </component>
 </project>
\ No newline at end of file

.idea/runConfigurations.xml

-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="RunConfigurationProducerService">
-    <option name="ignoredProducers">
-      <set>
-        <option value="com.android.tools.idea.compose.preview.runconfiguration.ComposePreviewRunConfigurationProducer" />
-      </set>
-    </option>
-  </component>
-</project>
\ No newline at end of file

src/main/java/formula/Formula.java

@@ -3,4 +3,10 @@ package formula;
 public interface Formula {
     String asString();
     double asValue();
+
+    String symbol();
+
+    double initialValue();
+
+    double cumulativeValue(double accumulator, double value);
 }

src/main/java/formula/Product.java

@@ -10,11 +10,26 @@ public class Product implements Formula{
 
     @Override
     public String asString() {
-        return "("+left.asString()+"*"+right.asString()+")";
+        return "("+left.asString()+symbol()+right.asString()+")";
     }
 
     @Override
     public double asValue() {
         return left.asValue()*right.asValue();
     }
+
+    @Override
+    public String symbol() {
+        return "*";
+    }
+
+    @Override
+    public double initialValue() {
+        return 1;
+    }
+
+    @Override
+    public double cumulativeValue(double accumulator, double value) {
+        return accumulator*value;
+    }
 }

src/main/java/formula/Square.java

@@ -16,4 +16,9 @@ public class Square implements Formula {
     public String asString() {
         return "("+formula.asString()+"²)";
     }
+
+    @Override
+    public String symbol() {
+        return "²";
+    }
 }

src/main/java/formula/Sum.java

@@ -15,6 +15,21 @@ public class Sum implements Formula {
 
     @Override
     public String asString() {
-        return "("+left.asString()+"+"+right.asString()+")";
+        return "("+left.asString()+symbol()+right.asString()+")";
+    }
+
+    @Override
+    public String symbol() {
+        return "+";
+    }
+
+    @Override
+    public double initialValue() {
+        return 0;
+    }
+
+    @Override
+    public double cumulativeValue(double accumulator, double value) {
+        return value+accumulator;
     }
 }

src/main/java/formula/Variable.java

@@ -18,4 +18,9 @@ public class Variable implements Formula {
     public double asValue() {
         return value;
     }
+
+    @Override
+    public String symbol() {
+        return "";
+    }
 }