Handle errors: division by 0 fix for +/- NaN

Author: gruszm

app/src/main/java/com/example/kalkulator/activities/AdvancedCalculatorActivity.java

@@ -129,7 +129,7 @@ public void percentOnClick(View v)
 
             String formattedOutput = DECIMAL_FORMAT.format(result).replace('.', ',');
 
-            if (formattedOutput.equals(INFINITY_SYMBOL))
+            if (formattedOutput.equals(INFINITY_SYMBOL) || formattedOutput.equals(MINUS_NAN) || formattedOutput.equals(NAN))
             {
                 Toast.makeText(this, "Cannot divide by 0", Toast.LENGTH_SHORT).show();
             }

app/src/main/java/com/example/kalkulator/activities/SimpleCalculatorActivity.java

@@ -149,7 +149,7 @@ public void equalsOnClick(View v)
 
             String formattedOutput = DECIMAL_FORMAT.format(result).replace('.', ',');
 
-            if (formattedOutput.equals(INFINITY_SYMBOL))
+            if (formattedOutput.equals(INFINITY_SYMBOL) || formattedOutput.equals(MINUS_NAN) || formattedOutput.equals(NAN))
             {
                 Toast.makeText(this, "Cannot divide by 0", Toast.LENGTH_SHORT).show();
             }

app/src/main/java/com/example/kalkulator/listeners/OperationOnClickListener.java

@@ -1,6 +1,7 @@
 package com.example.kalkulator.listeners;
 
 import android.view.View;
+import android.widget.Toast;
 import com.example.kalkulator.utils.CalculatorHandler;
 
 import static com.example.kalkulator.utils.CalculatorHandler.*;
@@ -22,6 +23,7 @@ public void onClick(View v)
         double prevValue;
         double currValue = Double.parseDouble(valueTextView.getText().toString().replace(',', '.'));
         boolean outputTooLong;
+        boolean operationChange = true;
 
         if (operationTextView.getText().toString().isEmpty())
         {
@@ -36,14 +38,22 @@ public void onClick(View v)
             formattedOutput = DECIMAL_FORMAT.format(result).replace('.', ',');
             outputTooLong = CalculatorHandler.isOutputTooLong(formattedOutput);
 
-            if (!outputTooLong)
+            if (formattedOutput.equals(INFINITY_SYMBOL) || formattedOutput.equals(MINUS_NAN) || formattedOutput.equals(NAN))
+            {
+                Toast.makeText(getToastMessageContext(), "Cannot divide by 0", Toast.LENGTH_SHORT).show();
+                operationChange = false;
+            }
+            else if (!outputTooLong)
             {
                 prevValueTextView.setText(formattedOutput);
             }
         }
 
-        operationTextView.setText(String.valueOf(operation));
-        newValueFlag = true;
+        if (operationChange)
+        {
+            operationTextView.setText(String.valueOf(operation));
+            newValueFlag = true;
+        }
 
         makeStandardVibration();
     }

app/src/main/java/com/example/kalkulator/utils/CalculatorHandler.java

@@ -16,6 +16,8 @@ public class CalculatorHandler
     public static final char CHAR_DIVIDE = '÷';
     public static final char CHAR_POWER = '^';
     public static final String INFINITY_SYMBOL = "\u221E"; // infinity symbol (dividing by zero)
+    public static final String MINUS_NAN = "-NaN";
+    public static final String NAN = "NaN";
     public static final int VALUE_TEXT_VIEW_MAX_SIZE = 10;
     public static final int OUTPUT_MAX_SIZE = 20;
     public static final DecimalFormat DECIMAL_FORMAT = new DecimalFormat("#.##########");
@@ -82,4 +84,9 @@ public static boolean isOutputTooLong(String formattedOutput)
 
         return outputTooLong;
     }
+
+    public static Context getToastMessageContext()
+    {
+        return toastMessageContext;
+    }
 }