java.lang.ClassCastException: android.widget.TextView. Pourquoi je reçois ça?

pour une raison quelconque, je suis une ClassCastException erreur. Je ne sais pas vraiment pourquoi.

Merci d'avance, je suis un nouveau programmeur et toute aide serait vraiment utile (no pun intended).

Code:

final EditText answerBox = (EditText) findViewById(R.id.answerBox);
final Button button = (Button) findViewById(R.id.button);
final TextView problem = (TextView) findViewById(R.id.problem);
final TextView status = (TextView) findViewById(R.id.status);
final TextView num = (TextView) findViewById(R.id.numerator);
final TextView denom = (TextView) findViewById(R.id.denominator);
button.setOnClickListener(new OnClickListener()
{
private String inputString;
public void onClick(View v)
{
inputString = problem.getText().toString();
int firstNumber = Integer.parseInt(inputString.substring(0,1));
int secondNumber = Integer.parseInt(inputString.substring(2,3));
int correct = firstNumber + secondNumber;
int input;
if(!answerBox.getText().toString().equals(""))
input = Integer.parseInt(answerBox.getText().toString());
else
input = -1;
if(input != -1)
{   
if(input == correct)
{
status.setText("Nice! You are correct!");
denom.setText(Integer.parseInt(denom.getText().toString()) +1);
num.setText(Integer.parseInt(num.getText().toString()) +1);
}
else
{
status.setText("Sorry, but your answer was wrong.");
denom.setText(Integer.parseInt(denom.getText().toString()) +1);
}
}
int a = (int) (Math.random() * 10);
int b = (int) (Math.random() * 10);
String newProblem = Integer.toString(a) + "+" + Integer.toString(b);
problem.setText(newProblem.toString());
answerBox.setText("");
}
});

Encore une fois, merci.

Des trucs de LogCat:

10-30 04:04:10.490: ERROR/AndroidRuntime(551): FATAL EXCEPTION: main
10-30 04:04:10.490: ERROR/AndroidRuntime(551): java.lang.RuntimeException: Unable to start    activity ComponentInfo{com.benhsu.Addition/com.benhsu.Addition.AdditionActivity}: java.lang.ClassCastException: android.widget.TextView
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at android.os.Looper.loop(Looper.java:123)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at android.app.ActivityThread.main(ActivityThread.java:3683)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at java.lang.reflect.Method.invokeNative(Native Method)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at java.lang.reflect.Method.invoke(Method.java:507)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at dalvik.system.NativeStart.main(Native Method)
10-30 04:04:10.490: ERROR/AndroidRuntime(551): Caused by: java.lang.ClassCastException: android.widget.TextView
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at com.benhsu.Addition.AdditionActivity.onCreate(AdditionActivity.java:24)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
10-30 04:04:10.490: ERROR/AndroidRuntime(551):     ... 11 more

XML fichier de Mise en page:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:weightSum="1">
<TextView  
android:layout_width="fill_parent" 
android:id="@+id/problem" android:layout_height="wrap_content"            android:text="@string/problemString"/>
<EditText android:layout_height="wrap_content" android:layout_width="match_parent" android:id="@+id/answerBox">
<requestFocus></requestFocus>
</EditText>
<TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="@string/status" android:id="@+id/status"></TextView>
<Button android:text="Button" android:layout_height="wrap_content" android:id="@+id/button" android:layout_width="wrap_content"></Button>
<RelativeLayout android:id="@+id/relativeLayout1" android:layout_height="wrap_content" android:layout_width="match_parent" android:layout_weight="0.14">
<TextView android:layout_width="wrap_content" android:layout_alignParentLeft="true" android:layout_height="wrap_content" android:layout_alignBottom="@+id/textView1" android:text="@string/score" android:id="@+id/textView2" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_alignBaseline="@+id/textView1"></TextView>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/numerator" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_alignParentTop="true" android:layout_toRightOf="@+id/textView2" android:layout_marginLeft="18dp" android:text="@string/numerator"></TextView>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/fraction" android:id="@+id/fraction" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_alignParentTop="true" android:layout_toRightOf="@+id/numerator" android:layout_marginLeft="14dp"></TextView>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/denominator" android:id="@+id/denominator" android:textAppearance="?android:attr/textAppearanceLarge" android:layout_alignParentTop="true" android:layout_toRightOf="@+id/fraction" android:layout_marginLeft="19dp"></TextView>
</RelativeLayout>
</LinearLayout>

source d'informationauteur bhsu