Issue
I'm having some difficulties with my android application.
Heres my code:
package activities;
import java.util.Vector;
import coursework.prototype.R;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class game_calculator extends Activity {
double currentTotal = 0.0; //Total of current calculation
String currentText = "0"; //Text displayed in the TextView
TextView Calculator_Display;
Vector<String> currentCalculations = new Vector<String>(); //Set up a vector to hold calculations
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.game_calculator);
Calculator_Display = (TextView) findViewById(R.id.display); //Locate the textview
Calculator_Display.setText( currentText ); //Set the text to default value
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
// MY CODE STARTS HERE
//Go Back button on click event
//Sets the current activity to the main menu
public void GoToMenu(View v)
{
startActivity( new Intent(this, game_selection.class) );
}
//Adds the number to the current display
public void CalculatorButton(View v)
{
//Get the buttons text
String buttons_text = ((Button) v).getText().toString();
//If no number has been inputed (screen will show 0)
if(currentText == "0")
{
currentText = buttons_text;
}
else //Add the number to the current display (after previous entered numbers)
{
currentText = currentText + buttons_text;
}
Calculator_Display.setText(currentText); //Set the display to the inputed number
}
//Performs the calculation with the current total and the display number
public void CalculatorFunction(View button)
{
switch( button.getId() )
{
case R.id.calculator_equals: //display the current total
currentCalculations.add( currentText ); //Add current number into the vector
if(currentCalculations.size() > 0) //Only process calculations if there's elements to process
CalculateTotal();
currentText = "0"; //Reset display
break;
case R.id.calculator_reset:
currentText = "0"; //Reset stored display
currentTotal = 0; //Reset stored total
currentCalculations.clear();
break;
case R.id.calculator_backspace:
//Delete the last entered number
if (currentText.length() > 0 && currentText.charAt(currentText.length()-1)=='0') {
currentText = currentText.substring(0, currentText.length()-1);
}
break;
default:
//Convert the display to an integer to be worked with
currentCalculations.add( currentText ); //Add current number into the vector
currentCalculations.add( ((Button) button).getText().toString() ); //Add the type of calculation to perform
currentText = "0"; //Reset display number
break;
}
Calculator_Display.setText( currentText ); //Set the new display
}
public void CalculateTotal()
{
//Set up variables
String currentElement; //Temporary string storage
String currentSign = " "; //Temporary sign storage
double currentNumber = 0; //Temporary number storage
Log.i("INFORMATION", "<=================== MY LOGS START HERE ===================>" );
Log.i("INFORMATION", "Size: " + Integer.toString(currentCalculations.size()) );
//Start processing
for(int c = 0; c <= currentCalculations.size(); c++) //Loops through elements to process
{
currentElement = currentCalculations.get( c ); //Get element from array
Log.i("INFORMATION", "Element " + Integer.toString(c) + " : " + currentElement );
//Check if the element is a sign
if(currentElement == "+" || currentElement == "-" || currentElement == "*" || currentElement == "/")
{
Log.i("INFORMATION", "Sign found!");
currentSign = currentElement; //Save into temporary storage to be used next loop
}
else // Element is a number
{
currentNumber = Double.parseDouble( currentElement ); //Convert number to integer
if(currentSign == "+")
currentTotal += currentNumber;
else if(currentSign == "-")
currentTotal -= currentNumber;
else if(currentSign == "*")
currentTotal = currentTotal * currentNumber;
else if(currentSign == "/")
currentTotal = currentTotal / currentNumber;
else
Log.i("INFORMATION", "THE PROGRAMS FUCKED UP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
}
}
Calculator_Display.setText( Double.toString( currentTotal ) ); //Display the currentTotal
Log.i("INFORMATION", "<=================== MY LOGS END HERE ===================>" );
}
}
The app crashes when I hit the equals button so I know the error is with CalculateTotal but am not sure why its crashing. If I do 7 + 8, the Logcat shows:
11-13 19:10:43.073: I/INFORMATION(1408): <=================== MY LOGS START HERE ===================>
11-13 19:10:43.073: I/INFORMATION(1408): Size: 5
11-13 19:10:43.114: I/INFORMATION(1408): Element 0 : 7
11-13 19:10:43.114: I/INFORMATION(1408): Element 1 : +
11-13 19:10:43.244: W/dalvikvm(1408): threadid=1: thread exiting with uncaught exception (group=0x414c4700)
11-13 19:10:43.476: E/AndroidRuntime(1408): FATAL EXCEPTION: main
11-13 19:10:43.476: E/AndroidRuntime(1408): java.lang.IllegalStateException: Could not execute method of the activity
11-13 19:10:43.476: E/AndroidRuntime(1408): at android.view.View$1.onClick(View.java:3633)
11-13 19:10:43.476: E/AndroidRuntime(1408): at android.view.View.performClick(View.java:4240)
11-13 19:10:43.476: E/AndroidRuntime(1408): at android.view.View$PerformClick.run(View.java:17721)
11-13 19:10:43.476: E/AndroidRuntime(1408): at android.os.Handler.handleCallback(Handler.java:730)
11-13 19:10:43.476: E/AndroidRuntime(1408): at android.os.Handler.dispatchMessage(Handler.java:92)
11-13 19:10:43.476: E/AndroidRuntime(1408): at android.os.Looper.loop(Looper.java:137)
11-13 19:10:43.476: E/AndroidRuntime(1408): at android.app.ActivityThread.main(ActivityThread.java:5103)
11-13 19:10:43.476: E/AndroidRuntime(1408): at java.lang.reflect.Method.invokeNative(Native Method)
11-13 19:10:43.476: E/AndroidRuntime(1408): at java.lang.reflect.Method.invoke(Method.java:525)
11-13 19:10:43.476: E/AndroidRuntime(1408): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-13 19:10:43.476: E/AndroidRuntime(1408): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-13 19:10:43.476: E/AndroidRuntime(1408): at dalvik.system.NativeStart.main(Native Method)
11-13 19:10:43.476: E/AndroidRuntime(1408): Caused by: java.lang.reflect.InvocationTargetException
11-13 19:10:43.476: E/AndroidRuntime(1408): at java.lang.reflect.Method.invokeNative(Native Method)
11-13 19:10:43.476: E/AndroidRuntime(1408): at java.lang.reflect.Method.invoke(Method.java:525)
11-13 19:10:43.476: E/AndroidRuntime(1408): at android.view.View$1.onClick(View.java:3628)
11-13 19:10:43.476: E/AndroidRuntime(1408): ... 11 more
11-13 19:10:43.476: E/AndroidRuntime(1408): Caused by: java.lang.NumberFormatException: Invalid double: "+"
11-13 19:10:43.476: E/AndroidRuntime(1408): at java.lang.StringToReal.invalidReal(StringToReal.java:63)
11-13 19:10:43.476: E/AndroidRuntime(1408): at java.lang.StringToReal.initialParse(StringToReal.java:151)
11-13 19:10:43.476: E/AndroidRuntime(1408): at java.lang.StringToReal.parseDouble(StringToReal.java:263)
11-13 19:10:43.476: E/AndroidRuntime(1408): at java.lang.Double.parseDouble(Double.java:295)
11-13 19:10:43.476: E/AndroidRuntime(1408): at activities.game_calculator.CalculateTotal(game_calculator.java:127)
11-13 19:10:43.476: E/AndroidRuntime(1408): at activities.game_calculator.CalculatorFunction(game_calculator.java:76)
11-13 19:10:43.476: E/AndroidRuntime(1408): ... 14 more
11-13 19:14:16.423: I/Process(1408): Sending signal. PID: 1408 SIG: 9
11-13 19:14:18.223: I/dalvikvm-heap(1446): Grow heap (frag case) to 4.082MB for 1536016-byte allocation
11-13 19:20:14.522: I/dalvikvm-heap(1545): Grow heap (frag case) to 4.082MB for 1536016-byte allocation
11-13 19:20:20.124: I/dalvikvm-heap(1545): Grow heap (frag case) to 5.822MB for 1536016-byte allocation
11-13 19:20:29.415: I/dalvikvm-heap(1545): Grow heap (frag case) to 7.856MB for 1536016-byte allocation
11-13 19:20:32.132: I/Choreographer(1545): Skipped 31 frames! The application may be doing too much work on its main thread.
11-13 19:20:43.032: I/INFORMATION(1545): <=================== MY LOGS START HERE ===================>
11-13 19:20:43.032: I/INFORMATION(1545): Size: 3
11-13 19:20:43.122: I/INFORMATION(1545): Element 0 : 7
11-13 19:20:43.162: I/INFORMATION(1545): THE PROGRAMS FUCKED UP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
11-13 19:20:43.172: I/INFORMATION(1545): Element 1 : +
11-13 19:20:43.224: W/dalvikvm(1545): threadid=1: thread exiting with uncaught exception (group=0x414c4700)
11-13 19:20:43.292: E/AndroidRuntime(1545): FATAL EXCEPTION: main
11-13 19:20:43.292: E/AndroidRuntime(1545): java.lang.IllegalStateException: Could not execute method of the activity
11-13 19:20:43.292: E/AndroidRuntime(1545): at android.view.View$1.onClick(View.java:3633)
11-13 19:20:43.292: E/AndroidRuntime(1545): at android.view.View.performClick(View.java:4240)
11-13 19:20:43.292: E/AndroidRuntime(1545): at android.view.View$PerformClick.run(View.java:17721)
11-13 19:20:43.292: E/AndroidRuntime(1545): at android.os.Handler.handleCallback(Handler.java:730)
11-13 19:20:43.292: E/AndroidRuntime(1545): at android.os.Handler.dispatchMessage(Handler.java:92)
11-13 19:20:43.292: E/AndroidRuntime(1545): at android.os.Looper.loop(Looper.java:137)
11-13 19:20:43.292: E/AndroidRuntime(1545): at android.app.ActivityThread.main(ActivityThread.java:5103)
11-13 19:20:43.292: E/AndroidRuntime(1545): at java.lang.reflect.Method.invokeNative(Native Method)
11-13 19:20:43.292: E/AndroidRuntime(1545): at java.lang.reflect.Method.invoke(Method.java:525)
11-13 19:20:43.292: E/AndroidRuntime(1545): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-13 19:20:43.292: E/AndroidRuntime(1545): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-13 19:20:43.292: E/AndroidRuntime(1545): at dalvik.system.NativeStart.main(Native Method)
11-13 19:20:43.292: E/AndroidRuntime(1545): Caused by: java.lang.reflect.InvocationTargetException
11-13 19:20:43.292: E/AndroidRuntime(1545): at java.lang.reflect.Method.invokeNative(Native Method)
11-13 19:20:43.292: E/AndroidRuntime(1545): at java.lang.reflect.Method.invoke(Method.java:525)
11-13 19:20:43.292: E/AndroidRuntime(1545): at android.view.View$1.onClick(View.java:3628)
11-13 19:20:43.292: E/AndroidRuntime(1545): ... 11 more
11-13 19:20:43.292: E/AndroidRuntime(1545): Caused by: java.lang.NumberFormatException: Invalid double: "+"
11-13 19:20:43.292: E/AndroidRuntime(1545): at java.lang.StringToReal.invalidReal(StringToReal.java:63)
11-13 19:20:43.292: E/AndroidRuntime(1545): at java.lang.StringToReal.initialParse(StringToReal.java:151)
11-13 19:20:43.292: E/AndroidRuntime(1545): at java.lang.StringToReal.parseDouble(StringToReal.java:263)
11-13 19:20:43.292: E/AndroidRuntime(1545): at java.lang.Double.parseDouble(Double.java:295)
11-13 19:20:43.292: E/AndroidRuntime(1545): at activities.game_calculator.CalculateTotal(game_calculator.java:126)
11-13 19:20:43.292: E/AndroidRuntime(1545): at activities.game_calculator.CalculatorFunction(game_calculator.java:76)
11-13 19:20:43.292: E/AndroidRuntime(1545): ... 14 more
11-13 19:25:43.513: I/Process(1545): Sending signal. PID: 1545 SIG: 9
11-13 19:25:44.963: I/dalvikvm-heap(1577): Grow heap (frag case) to 4.082MB for 1536016-byte allocation
Solution
never ever ever use == to check equality for strings in Java. you must always use
string1.equals(string2)
the line
if (currentString == "+")
will always return false, so you must use
if (currentString.equals("+"))
Answered By - panini
Answer Checked By - Mary Flores (JavaFixing Volunteer)
