Android : Seek bar and button don't work

I want to write a simple android application with one button and one slider : my java program is as following :

package com.example.android.apis.view;

import com.example.android.apis.R;

import android.app.Activity;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextSwitcher;
import android.widget.TextView;
import android.widget.ViewSwitcher;

/**
 * Uses a TextSwitcher.
 */
public class TextSwitcher1 extends Activity implements ViewSwitcher.ViewFactory,
        View.OnClickListener, OnSeekBarChangeListener {

    SeekBar mSeekBar;
    TextView mProgressText;
    TextView mTrackingText;
    private TextSwitcher mSwitcher;

    private int mCounter = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.text_switcher_1);
        setContentView(R.layout.seekbar_1);

        mSeekBar = (SeekBar)findViewById(R.id.seek);
        mSeekBar.setOnSeekBarChangeListener(this);

        mProgressText = (TextView)findViewById(R.id.progress);
        mTrackingText = (TextView)findViewById(R.id.tracking);

        mSwitcher = (TextSwitcher) findViewById(R.id.switcher);
        mSwitcher.setFactory(this);

        Button nextButton = (Button) findViewById(R.id.next);
        nextButton.setOnClickListener(this);

        updateCounter();
    }

    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromTouch) {
        mProgressText.setText(progress + " " + 
                getString(R.string.seekbar_from_touch) + "=" + fromTouch);
    }

    public void onStartTrackingTouch(SeekBar seekBar) {
        mTrackingText.setText(getString(R.string.seekbar_tracking_on));
    }

    public void onStopTrackingTouch(SeekBar seekBar) {
        mTrackingText.setText(getString(R.string.seekbar_tracking_off));
    }

    public void onClick(View v) {
        mCounter++;
        updateCounter();
    }

    private void updateCounter() {
        mSwitcher.setText(String.valueOf(mCounter));
    }

    public View makeView() {
        TextView t = new TextView(this);
        t.setGravity(Gravity.TOP | Gravity.CENTER_HORIZONTAL);
        t.setTextSize(36);
        return t;
    }
}

I got this error : The method setOnSeekBarChangeListener(SeekBar.OnSeekBarChangeListener) in the type SeekBar is not applicable for the arguments (TextSwitcher1) in this line : mSeekbar.setonSeekbarChangeListener(this);

I don't know what is this problem,would you please help me to solve it. Thank you very much in advance, Stefan