我正在尝试从用户那里获取值并使用 SQLite 数据库显示它。我使用了以下代码，但在模拟器上运行时出现错误“不幸停止”。DBAdapter.java 文件用于创建数据库，result.java 使用函数。
结果.java
public class result_mode extends Activity implements OnClickListener{
EditText e1, e2, e3, e4, e5;
DBAdapter db = new DBAdapter(this);
Intent saveIntent;
Intent homeIntent;
Intent abortIntent;
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.res);
DBAdapter db = new DBAdapter(this);
getFullList();
e2 = (EditText)findViewById(R.id.name);
e1=(EditText)findViewById(R.id.id);
e3=(EditText)findViewById(R.id.age);
e5=(EditText)findViewById(R.id.doc);
e4=(EditText)findViewById(R.id.editText2);
Button b1 = (Button) findViewById(R.id.abort);
Button b2 = (Button)findViewById(R.id.home);
Button b3 = (Button)findViewById(R.id.save);
b1.setOnClickListener(this);
b2.setOnClickListener(this);
b3.setOnClickListener(this);
}
public void DisplayTitle(Cursor c)
{
Toast.makeText(this,
"UID: " + c.getString(0) + "\n" +
"NAME: " + c.getString(1) + "\n" +
"AGE: " + c.getString(2) + "\n" +
"CONTACT: " + c.getString(3)+ "\n" +
"Referred By: " + c.getString(4),
Toast.LENGTH_LONG).show();
}
public void insert() {
//insert
db.open();
long id;
id = db.insertPatient(e1.toString(), e2.toString(), e3.toString(),
e4.toString(), e5.toString());
db.close();
}
public void getFullList(){
db.open();
Cursor c = db.getResult();
if (c.moveToFirst())
{
do {
DisplayTitle(c);
} while (c.moveToNext());
}
db.close();
}
public void handleClick(View v) {
insert();
getFullList();
}
public void onClick(final View v) {
switch(v.getId()){
case R.id.save:
saveIntent = new Intent(result_mode.this,menuActivity.class);
startActivity(saveIntent);
break;
case R.id.abort:
abortIntent = new Intent(result_mode.this,test_me.class);
startActivity(abortIntent);
break;
case R.id.home:
homeIntent= new Intent(result_mode.this,TestActivity.class);
startActivity(homeIntent);
break;
}}
}
DBAdapter.java
public class DBAdapter
{
public static final String KEY_UID = "_id";
public static final String KEY_NAME = "name";
public static final String KEY_CONTACT = "contact_num";
public static final String KEY_AGE = "age";
public static final String KEY_DOC = "doc";
private static final String TAG = "DBAdapter";
private static final String DATABASE_NAME = "test";
private static final String DATABASE_TABLE = "table1";
private static final int DATABASE_VERSION = 1;
//drop table titles
private static final String DATABASE_CREATE ="create table patient ("
+"ID INTEGER primary key AUTOINCREMENT,"
+ "NAME TEXT,"
+ "AGE NUMBER,"
+ "CONTACT NUMBER,"
+ "DOC TEXT);";
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
this.DBHelper = new DatabaseHelper(this.context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(DATABASE_NAME);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion)
{
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
onCreate(db);
}
}
public DBAdapter open() throws SQLException
{
this.db = this.DBHelper.getWritableDatabase();
return this;
}
public void close()
{
this.DBHelper.close();
}
//---insert a title into the database---
public long insertPatient( String id, String name, String age, String contact, String doc )
{
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_NAME, name);
initialValues.put(KEY_UID, id);
initialValues.put(KEY_CONTACT, contact);
initialValues.put(KEY_AGE, age);
initialValues.put(KEY_DOC, doc);
return db.insert(DATABASE_TABLE, null, initialValues);
}
/*---deletes a particular patient---
public boolean deletePatient(long rowId)
{
return db.delete(DATABASE_TABLE, KEY_ROWID +
"=" + rowId, null) > 0;
}*/
//---retrieves all the titles---
public Cursor getResult()
{
return db.query(DATABASE_TABLE, new String[] {
KEY_UID ,KEY_NAME, KEY_AGE, KEY_CONTACT,KEY_DOC
},
null,
null,
null,
null,
null);
}
//---retrieves a particular title---
public Cursor getPatient(long id) throws SQLException
{
Cursor mCursor =
db.query(true, DATABASE_TABLE, new String[] {
KEY_UID ,KEY_NAME, KEY_AGE, KEY_CONTACT,KEY_DOC
}
, KEY_UID + "=" + id,
null, null, null, null, null
);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
//---updates a title---
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
}
}
活动日志：
06-13 12:17:23.581: D/AndroidRuntime(565): Shutting down VM
06-13 12:17:23.581: W/dalvikvm(565): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
06-13 12:17:23.621: E/AndroidRuntime(565): FATAL EXCEPTION: main
06-13 12:17:23.621: E/AndroidRuntime(565): java.lang.RuntimeException: Unable to start activity ComponentInfo{achira.test/achira.test.result_mode}: android.database.sqlite.SQLiteException: Can't downgrade database from version 33 to 1
06-13 12:17:23.621: E/AndroidRuntime(565): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.app.ActivityThread.access$600(ActivityThread.java:123)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.os.Handler.dispatchMessage(Handler.java:99)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.os.Looper.loop(Looper.java:137)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.app.ActivityThread.main(ActivityThread.java:4424)
06-13 12:17:23.621: E/AndroidRuntime(565): at java.lang.reflect.Method.invokeNative(Native Method)
06-13 12:17:23.621: E/AndroidRuntime(565): at java.lang.reflect.Method.invoke(Method.java:511)
06-13 12:17:23.621: E/AndroidRuntime(565): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
06-13 12:17:23.621: E/AndroidRuntime(565): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
06-13 12:17:23.621: E/AndroidRuntime(565): at dalvik.system.NativeStart.main(Native Method)
06-13 12:17:23.621: E/AndroidRuntime(565): Caused by: android.database.sqlite.SQLiteException: Can't downgrade database from version 33 to 1
06-13 12:17:23.621: E/AndroidRuntime(565): at android.database.sqlite.SQLiteOpenHelper.onDowngrade(SQLiteOpenHelper.java:307)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:168)
06-13 12:17:23.621: E/AndroidRuntime(565): at achira.test.DBAdapter.open(DBAdapter.java:62)
06-13 12:17:23.621: E/AndroidRuntime(565): at achira.test.result_mode.getFullList(result_mode.java:69)
06-13 12:17:23.621: E/AndroidRuntime(565): at achira.test.result_mode.onCreate(result_mode.java:30)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.app.Activity.performCreate(Activity.java:4465)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
06-13 12:17:23.621: E/AndroidRuntime(565): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
06-13 12:17:23.621: E/AndroidRuntime(565): ... 11 more
new log :
06-13 13:01:33.395: E/AndroidRuntime(897): at da lvik.system.NativeStart.main(Native Method)
06-13 13:01:33.395: E/AndroidRuntime(897): Caused by: java.lang.reflect.InvocationTargetException
06-13 13:01:33.395: E/AndroidRuntime(897): at java.lang.reflect.Method.invokeNative(Native Method)
06-13 13:01:33.395: E/AndroidRuntime(897): at java.lang.reflect.Method.invoke(Method.java:511)
06-13 13:01:33.395: E/AndroidRuntime(897): at android.view.View$1.onClick(View.java:3039)
06-13 13:01:33.395: E/AndroidRuntime(897): ... 11 more
06-13 13:01:33.395: E/AndroidRuntime(897): Caused by: java.lang.NullPointerException
06-13 13:01:33.395: E/AndroidRuntime(897): at achira.test.result_mode.insert(result_mode.java:61)
06-13 13:01:33.395: E/AndroidRuntime(897): at achira.test.result_mode.handleClick(result_mode.java:81)
06-13 13:01:33.395: E/AndroidRuntime(897): ... 14 more