성적처리 앱을 만드는 중인데요 ....
 DB 입출력되는 거 확인하고, 성적입력하는 액티비티 구성하고나서,
두 액티비티를 연결하려고 intent 로 값 넘겼더니 죽어버리네요 ㅜㅜ
풀 소스 올릴께요. 이유가 뭔지 모르겠어요 ㅜㅜ
Demo.java ::::: DB 입출력을 처리하고, 뷰로 출력해줌.
NewGrade.java ::::: 성적입력하는 액티비티

Demo.java
C:\Users\mk\workspace\Demo\src\sm\mm\Demo.javaDB처리하는 액티비티
package sm.mm.Demo;
import java.util.ArrayList;
import java.util.HashMap;
import android.app.ListActivity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.SimpleAdapter;

public class Demo extends ListActivity {
 /** Called when the activity is first created. */
 private SQLiteDatabase db;
 Cursor mCursor;
 String mCode, mSubject,mUnit, mGrade;
 
 
 
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
   
  //----------버튼부----------------
 Button btnAdd=(Button)findViewById(R.id.call);
    btnAdd.setOnClickListener(new Button.OnClickListener() {
     
     public void onClick(View v) {
      Intent intent = new Intent(Demo.this, NewGrade.class);
      startActivity(intent);
        }
    });
  //---------------버튼부 끝---------
  //------------인텐트 받아오기 --------
    Bundle extras = getIntent().getExtras();
    mCode = extras.getString("Code");
    mSubject = extras.getString("Subject");
    mUnit = extras.getString("Unit");
    mGrade = extras.getString("Unit");
  
   //----------- 데이터베이스 처리--------
  db = openOrCreateDatabase("MyUserDB", MODE_PRIVATE, null);
  db.execSQL("drop table if exists users1"); 
  db.execSQL("create table users1 ("
    + "_id integer primary key autoincrement, "
    + "Code text not null, " + "Subject text not null,"
    + "Unit text not null," + "Grade text not null);");

  // 데이터 1 삽입문
  db.execSQL("insert into users1 " + " (Code, Subject, Unit, Grade)"
    + " values ('01635', '모바일프로그래밍', '3', 'A');");
  
  db.execSQL("insert into users1 " + " (Code, Subject, Unit, Grade)"
      + " values ('"+mCode+"','"+mSubject+"','"+ mUnit+"','" +mGrade+"');");
    
  //학점에 따라 쿼리?
  mCursor = db.query("users1", // String table
    new String[] { "Code", "Subject", "Unit", "Grade" }, // String[]
    // columns
    "unit > 1", // String selection
    null, // String[] selectionArgs
    null, // String groupBy
    null, // String having
    "_id", // String orderBy
    "5"); // String limit

  ArrayList<HashMap<String, String>> mList = new ArrayList<HashMap<String, String>>();
  if (mCursor != null) {
   if (mCursor.moveToFirst()) {
    do {
     HashMap<String, String> item = new HashMap<String, String>();
     for (int j = 0; j < mCursor.getColumnCount(); j++) {
      item
        .put(mCursor.getColumnName(j), mCursor
          .getString(j));
     }
     mList.add(item);
    } while (mCursor.moveToNext());
   }
  }

  SimpleAdapter adapter2 = new SimpleAdapter(this, mList, R.layout.excel,
    new String[] { "Code", "Subject", "Unit", "Grade" },
    new int[] { R.id.text1, R.id.text2, R.id.text3, R.id.text4 });
  setListAdapter(adapter2); 
  if (db != null) {
   db.close();
  }
 } 
}


NewGrade.java
C:\Users\mk\workspace\Demo\src\sm\mm\Demo\NewGrade.java
package sm.mm.Demo;
C:\Users\mk\workspace\Demo\src\sm\mm\Demo\NewGrade.java
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.Spinner;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.RadioGroup.OnCheckedChangeListener;

public class NewGrade extends Activity implements OnCheckedChangeListener {
 ArrayAdapter<CharSequence> adspin;
 String str, str2, mCode, mSubject, mUnit, mGrade;
 EditText mEdit1, mEdit2;
 
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.newgrade);
    
    //---------- 에디트 텍스트박스 설정 : 학수번호, 과목이름 ------
    mEdit1 = (EditText)findViewById(R.id.in_code);
    
    
    mEdit2 = (EditText)findViewById(R.id.in_sub);
    
    
    //---------- 라디오 그룹 설정 : 이수학점
    //이수학점(unit) - string
    RadioGroup unitgroup = (RadioGroup)findViewById(R.id.unitgroup);
    unitgroup.setOnCheckedChangeListener(this);
    
    
    //---------- 스피너 설정 ----------
    //성적(grade) - string
   Spinner spin = (Spinner)findViewById(R.id.Spin_grade);
   spin.setPrompt("성적을 고르셈.");
   adspin = ArrayAdapter.createFromResource(this, R.array.grade, 
     android.R.layout.simple_spinner_item);
   adspin.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
   spin.setAdapter(adspin);
   spin.setOnItemSelectedListener(new OnItemSelectedListener() {
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
    // Toast.makeText(NewGrade.this,adspin.getItem(position) + "선택",
    //   Toast.LENGTH_SHORT).show();
     switch(position){
     case 0: mGrade ="A"; break;
     case 1: mGrade ="B"; break;
     case 2: mGrade ="C"; break;
     case 3: mGrade ="D"; break;
     case 4: mGrade ="E"; break;
     
     }
    }
    public void onNothingSelected(AdapterView<?> parent) {
    }
   });
   
   //---------인텐트간 통신-----------
   //인텐트에 저장된 값들을 Demo.java로 보냄
   
   Button btnOK = (Button)findViewById(R.id.ok);
   btnOK.setOnClickListener(new View.OnClickListener() {
    
    public void onClick(View v) {
     
     String  mCode, mSubject;
     
     //EditText 내용을 추출한다.
     mCode = mEdit1.getText().toString();
        mSubject = mEdit2.getText().toString();
        
     //extras 데이터를 담은 intent를 명시적으로 호출한다.
     Intent intent = new Intent(NewGrade.this, Demo.class);
     
     Bundle extras = new Bundle(); 
     extras.putString("code", mCode);
     extras.putString("subject", mSubject);      
     extras.putString("unit", mUnit);
     extras.putString("grade", mGrade);
     
     //intent에 extras를 담는다.
     intent.putExtras(extras);
     
     startActivity(intent);
    }
   });
   /*
   Button btnOK=(Button)findViewById(R.id.ok);
   btnOK.setOnClickListener(new Button.OnClickListener() {
    public void onClick(View v) {
     //----------sender------------
     Intent intent = new Intent(NewGrade.this, Demo.class);
     Bundle extras = new Bundle();
     extras.putString("code", mCode);
     extras.putString("subject", mSubject);      
     extras.putString("unit", mUnit);
     extras.putString("grade", mGrade);
     
     intent.putExtras(extras);
     
     startActivity(intent);
      
     //setResult(RESULT_OK,intent);
     //finish();
    }
    
   });
   */
   Button btnCancel=(Button)findViewById(R.id.cancel);
   btnCancel.setOnClickListener(new Button.OnClickListener() {
    public void onClick(View v) {
     setResult(RESULT_CANCELED);
     finish();
    }
   });
  }

 @Override
 public void onCheckedChanged(RadioGroup group, int checkedId) 
 {
  if (group.getId() == R.id.unitgroup) 
  {
   switch (checkedId) 
   {
   case R.id.unit_1:
    mUnit ="1";
    break;
   case R.id.unit_2:
    mUnit="2";
    break;
   case R.id.unit_3:
    mUnit="3";
    break;
   }
  }
 }
 
}