CODEWITHSUNDEEP
androidviewcasting
DJDave
DJDave

Reputation: 915

button press in Android app creates casting error

I am new to android development, and have been trying to use the beginner's tutorial as my starting point for developing a simple app. There is one screen, with an image, a row of four buttons, a textbox for the user to enter a pin, and a textview to display results.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/linear_layout_1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ImageView
       android:id="@+id/imageView1"
       android:contentDescription="@string/image"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
        android:src="@drawable/skytrek"
       />

    <LinearLayout
    android:id="@+id/linear_layout_2"
        android:layout_width="wrap_content"
       android:layout_height="wrap_content"
        android:orientation="horizontal" >

                <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="14sp"
        android:text="@string/button_today"
        android:onClick="today_click" />

            <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="14sp"
        android:text="@string/button_tomorrow"
        android:onClick="tomorrow_click" /> 

            <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="14sp"
        android:text="@string/button_this_week"
        android:onClick="this_week_click" /> 

          <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="14sp"
        android:text="@string/button_next_week"
        android:onClick="next_week_click" />
    </LinearLayout>

        <EditText android:id="@+id/editText1"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:hint="@string/edit_message" />

    <TextView
       android:id="@+id/textView1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="@string/init_message"/>


</LinearLayout>

I have code to deliver the results I want based on the button pressed - all fine. But then I wanted the user to enter a PIN as well as pressing a button, so I added the EditText control. This threw the following error:

E/AndroidRuntime(28578): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.EditText

My Java class:

private String content = null;  
private TextView textView1;
private EditText editText1;

public void today_click(View view) {
    getPage("today");
}
public void tomorrow_click(View view) {
    getPage("tomorrow");
}
public void this_week_click(View view) {
    getPage("thisweek");
}
public void next_week_click(View view) {
    getPage("nextweek");
}

public void getPage(String strParam) {

    editText1 = (EditText) findViewById(R.id.editText1);
    String message = editText1.getText().toString();

    if (message.equals("4567")) {

                content = "PIN recognised";
    } else {
        content = "PIN not recognised";
    }
    textView1 = (TextView) findViewById(R.id.textView1);
    textView1.setText(content);
}

I thought I had done something silly, using the name of a TextView instead of an EditText control, but I can't find it if I have.

The error is being thrown at the line

getPage("thisweek");

I didn't understand how this line involved views of any sort, but of course the function heading 

this_week_click(View view)

does, and when I changed the order of the TextView and the EditText in the XML file (so that the TextView comes first), the error disappeared. It is as if the "view" being passed is not the button, but the nearest widget to the button. I have read

existence of parameter (View view)

but it only seems to confirm my (mis)understanding that a button should be passed as the view parameter. I have also tried cleaning the project, and building a completely new project. What on earth is causing the casting error?

Upvotes: 1

Views: 128

Answers (4)

Lal
Lal

Reputation: 14810

Try cleaning your project and run it again.. Eclipse -> Project menu ->Clean

It is because eclipse gets confused when we play around in the xml file ;)

Upvotes: 0

anjaneya
anjaneya

Reputation: 708

Everytime if you make any changes in xml or any interchange of position of views in xml or change of id's,you need to clean build your project.If not you will get this exception.

Upvotes: 2

Satyaki Mukherjee
Satyaki Mukherjee

Reputation: 2879

Hello I have tested your code, your code is fine. Please clean your project from

select your project then click on Project and then Clean and also check the Build Automatically . Your auto generated class R is not generated properly.

Upvotes: 1

allemattio
allemattio

Reputation: 1848

If you're using Eclipse, go to the menu voice "Project" and select "Clean"

Sometimes Eclipse has some problem with ids, by cleaning the project you regenerate them..

Upvotes: 5

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