please explain this unknown ClassCastException

[shawn peter]

this is my activity.xml file

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".Leave" >

    <LinearLayout
        android:id="@+id/first"
        android:layout_marginBottom="100dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/hello_world" />

        <Button
            android:id="@+id/btnLogin"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dip"
            android:text="Login" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/second"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/first" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/hello_world" />

        <Button
            android:id="@+id/btnLogin"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dip"
            android:text="Login" />
    </LinearLayout>

</RelativeLayout>

this is my Leave.java class

package com.android.list;

import java.util.Calendar;

import com.android.loginactivity.R;
import com.android.loginactivity.R.layout;
import com.android.loginactivity.R.menu;

import android.os.Bundle;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.DatePicker;

public class Leave extends Activity implements OnClickListener {

	private Button mDateButton;

	private Calendar mCalen;
	private int day;
	private int month;
	private int year;

	private static final int DATE_PICKER_ID = 0;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		try {
			super.onCreate(savedInstanceState);
			setContentView(R.layout.activity_leave);
			mDateButton = (Button) findViewById(R.id.first);
			mCalen = Calendar.getInstance();
			day = mCalen.get(Calendar.DAY_OF_MONTH);
			month = mCalen.get(Calendar.MONTH);
			year = mCalen.get(Calendar.YEAR);
			mDateButton.setOnClickListener(this);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	@Override
	@Deprecated
	protected Dialog onCreateDialog(int id) {

		switch (id) {
		case DATE_PICKER_ID:
			return new DatePickerDialog(this, datePickerListener, year, month,
					day);
		}
		return null;
	}

	private DatePickerDialog.OnDateSetListener datePickerListener = new DatePickerDialog.OnDateSetListener() {

		// while dialog box is closed, below method is called.
		public void onDateSet(DatePicker view, int selectedYear,
				int selectedMonth, int selectedDay) {
			year = selectedYear;
			month = selectedMonth;
			day = selectedDay;

			// Set the Date String in Button
			mDateButton.setText(day + " / " + (month + 1) + " / " + year);
		}
	};

	@Override
	public void onClick(View v) {
		showDialog(DATE_PICKER_ID);

	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.leave, menu);
		return true;
	}

}

when i run this code i am getting below error?

09-21 13:51:18.838: W/System.err(4440): java.lang.ClassCastException: android.widget.LinearLayout
09-21 13:51:18.838: W/System.err(4440): 	at com.android.list.Leave.onCreate(Leave.java:35)
09-21 13:51:18.838: W/System.err(4440): 	at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-21 13:51:18.838: W/System.err(4440): 	at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1623)
09-21 13:51:18.838: W/System.err(4440): 	at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1675)
09-21 13:51:18.838: W/System.err(4440): 	at android.app.ActivityThread.access$1500(ActivityThread.java:121)
09-21 13:51:18.838: W/System.err(4440): 	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:943)
09-21 13:51:18.838: W/System.err(4440): 	at android.os.Handler.dispatchMessage(Handler.java:99)
09-21 13:51:18.838: W/System.err(4440): 	at android.os.Looper.loop(Looper.java:130)
09-21 13:51:18.838: W/System.err(4440): 	at android.app.ActivityThread.main(ActivityThread.java:3701)
09-21 13:51:18.838: W/System.err(4440): 	at java.lang.reflect.Method.invokeNative(Native Method)
09-21 13:51:18.838: W/System.err(4440): 	at java.lang.reflect.Method.invoke(Method.java:507)
09-21 13:51:18.848: W/System.err(4440): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
09-21 13:51:18.848: W/System.err(4440): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:624)
09-21 13:51:18.848: W/System.err(4440): 	at dalvik.system.NativeStart.main(Native Method)

[Ulf Dittmer]

What kind of object is the code retrieving? And what kind of object is it trying to cast it to? And what kind of cast is the error message complaining about? Answer these 3 questions, and you should be on your way to solving the problem.

(I am surprised the code even builds. I wouldn't have thought that having multiple UI elements in one layout file with the same ID even works. At the least, it's majorly confusing. But that has nothing to do with the issue at hand - it's an additional problem.)

[Ulf Dittmer]

On taking a second look - what is the relationship between the code and the layout file? They don't seem to go together.

[Naishadh Parmar]

On line 35: You are trying to get a view which is actually a LinearLayout and cast it to a Button. That is why you get a ClassCastException.

[Naishadh Parmar]

I am sorry:

In line 35..................