V2

app/src/main/java/io/n0x/android/java_mot_testing/MainActivity.java

@@ -1,29 +1,23 @@
 package io.n0x.android.java_mot_testing;
 
-import android.annotation.SuppressLint;
 import android.os.Bundle;
 import android.util.Log;
-import android.view.View;
-import android.widget.TextView;
 
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.databinding.DataBindingUtil;
 
 import io.n0x.android.java_mot_testing.databinding.Ex9DataBindingBinding;
+import io.n0x.android.java_mot_testing.helper.Converter;
 
-public class MainActivity extends AppCompatActivity implements View.OnClickListener {
+public class MainActivity extends AppCompatActivity{
     // For debugging
     private static final String TAG = MainActivity.class.getName();
-    // Local calculator instance
-    private FractionCalculator calc;
-
-    private int test;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        // create calculator instance
+        // Local calculator instance
-        calc = new FractionCalculator();
+        FractionCalculator calc = new FractionCalculator();
 
         // set a value for testing
         calc.setEnumResult(0);
@@ -32,37 +26,16 @@ public class MainActivity extends AppCompatActivity implements View.OnClickListe
         // Bind instance of FractionCalculator to view
         Ex9DataBindingBinding binding = DataBindingUtil.setContentView(this, R.layout.ex9_data_binding);
         binding.setCalc(calc);
+        // set initial value for the arithmetical method
+        calc.setArithMethod(FractionCalculator.ARTIH.ADD);
 
-        // Button Listeners
+        /*
-        findViewById(R.id.button_add).setOnClickListener(this);
+        // Converter to get null values
-        findViewById(R.id.button_sub).setOnClickListener(this);
+        Converter conv = new Converter();
-        findViewById(R.id.button_mult).setOnClickListener(this);
+        binding.setConv(conv);
-        findViewById(R.id.button_div).setOnClickListener(this);
+        //*/
-        findViewById(R.id.button_calc).setOnClickListener(this);
 
         // Log create action
         Log.d(TAG, "MainActivity started");
     }
-
-    @SuppressLint("NonConstantResourceId")
-    @Override
-    public void onClick(View v) {
-        switch(v.getId()){
-            case R.id.button_add:
-                calc.setArithMethod(FractionCalculator.ARTIH.ADD);
-                break;
-            case R.id.button_sub:
-                calc.setArithMethod(FractionCalculator.ARTIH.SUBTRACT);
-                break;
-            case R.id.button_mult:
-                calc.setArithMethod(FractionCalculator.ARTIH.MULTIPLICATE);
-                break;
-            case R.id.button_div:
-                calc.setArithMethod(FractionCalculator.ARTIH.DIVIDE);
-                break;
-            case R.id.button_calc:
-                calc.calculateResult();
-                break;
-        }
-    }
 }

app/src/main/java/io/n0x/android/java_mot_testing/helper/Converter.java

@@ -0,0 +1,18 @@
+package io.n0x.android.java_mot_testing.helper;
+
+import androidx.databinding.InverseMethod;
+
+public class Converter {
+    @InverseMethod("toInt")
+    public static String toString(int val){
+        if(val == 0){
+            return null;
+        }
+        return String.valueOf(val);
+    }
+    public static int toInt(String val){
+        if(val == null || val.isEmpty())
+            return 0;
+        return Integer.parseInt(val);
+    }
+}

app/src/main/res/layout/ex9_data_binding.xml

@@ -7,6 +7,9 @@
         <variable
             name="calc"
             type="io.n0x.android.java_mot_testing.FractionCalculator" />
+        <variable
+            name="conv"
+            type="io.n0x.android.java_mot_testing.helper.Converter" />
     </data>
 
     <androidx.constraintlayout.widget.ConstraintLayout
@@ -14,6 +17,7 @@
         android:layout_height="match_parent">
 
         <Button
+            android:onClick="@{() -> calc.setArithMethod(io.n0x.android.java_mot_testing.FractionCalculator.ARTIH.ADD)}"
             android:id="@+id/button_add"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
@@ -26,6 +30,7 @@
             app:layout_constraintTop_toTopOf="parent" />
 
         <Button
+            android:onClick="@{() -> calc.setArithMethod(io.n0x.android.java_mot_testing.FractionCalculator.ARTIH.SUBTRACT)}"
             android:id="@+id/button_sub"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
@@ -36,6 +41,7 @@
             app:layout_constraintTop_toTopOf="parent" />
 
         <Button
+            android:onClick="@{() -> calc.setArithMethod(io.n0x.android.java_mot_testing.FractionCalculator.ARTIH.MULTIPLICATE)}"
             android:id="@+id/button_mult"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
@@ -46,6 +52,7 @@
             app:layout_constraintTop_toTopOf="parent" />
 
         <Button
+            android:onClick="@{() -> calc.setArithMethod(io.n0x.android.java_mot_testing.FractionCalculator.ARTIH.DIVIDE)}"
             android:id="@+id/button_div"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
@@ -136,6 +143,7 @@
             app:layout_constraintTop_toBottomOf="@+id/enumRight" />
 
         <Button
+            android:onClick="@{() -> calc.calculateResult()}"
             android:id="@+id/button_calc"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"