activityに対するいくつかの理解と用法の記録

package com.example.testthread;

import android.app.Activity;
import android.content.Intent;
import android.nfc.Tag;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
    private TextView mTextView;

    private Handler mHandler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            if (msg.what == 0x123) {
                Toast.makeText(MainActivity.this,
                        mTextView.getText().toString(), Toast.LENGTH_SHORT)
                        .show();
                Intent intent = new Intent(MainActivity.this, OtherActivity.class);
                MainActivity.this.startActivity(intent);
            }

        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        new Thread(new Runnable() {

            @Override
            public void run() {
                // Looper.prepare();
                Message msg = Message.obtain();
                msg.what = 0x123;
                mHandler.sendMessageDelayed(msg, 5000);

            }
        }).start();

        finish();

    }

    @Override
    public void onContentChanged() {
        mTextView = (TextView) findViewById(R.id.id_text);
    }

    @Override
    protected void onDestroy() {
        Log.e("TAG", "onDestory");
        super.onDestroy();
    }

}