安卓开发“出错总结”

package com.example.proj_2_;


import java.util.Timer;
import java.util.TimerTask;


import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.PowerManager;
import android.text.format.Time;
import android.widget.TextView;
import android.widget.Toast;


public class FunMain extends Activity {

TextView tv_Time = (TextView) findViewById(R.id.nowtime);

/*       放在与  onCreate(Bundle savedInstanceState) { 同层时出错：11-20 16:21:36.120: W/dalvikvm(3754): threadid=1: thread exiting with uncaught exception (group=0xb5027180)  
11-20 16:21:36.120: E/AndroidRuntime(3754): FATAL EXCEPTION: main 
*/

tv_Time.setText(hour + " H " + minute + " M " + second + " S\n");

//其他代码。。。。
@Override
protected void onCreate(Bundle savedInstanceState) {
 


// TODO 自动生成的方法存根
super.onCreate(savedInstanceState);
setContentView(R.layout.mainfun_xml);
 
}


}