我试图将数据输入注册表单以保存到数据库中。 这是我的数据库： 包com.NebulaNewsCo.gameofwin;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class gowDbAdapter {
public static final String KEY_USERNAME = "username";
public static final String KEY_PASSWORD = "password";
public static final String KEY_ROWID = "_id";
private static final String TAG = "gowDbAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
/**
* Database creation sql statement
*/
private static final String DATABASE_CREATE =
"create table notes (_id integer primary key autoincrement, "
+ "title text not null, body text not null);";
private static final String DATABASE_NAME = "gow";
private static final String DATABASE_TABLE = "users";
private static final int DATABASE_VERSION = 2;
private final Context mCtx;
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_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS notes");
onCreate(db);
}
}
/**
* Constructor - takes the context to allow the database to be
* opened/created
*
* @param ctx the Context within which to work
*/
public gowDbAdapter(Context ctx) {
this.mCtx = ctx;
}
/**
* Open the notes database. If it cannot be opened, try to create a new
* instance of the database. If it cannot be created, throw an exception to
* signal the failure
*
* @return this (self reference, allowing this to be chained in an
* initialization call)
* @throws SQLException if the database could be neither opened or created
*/
public gowDbAdapter open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDbHelper.close();
}
/**
* @param username
* @param password
* @return rowId or -1 if failed
*/
public long createUser(String username, String password) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_USERNAME, username);
initialValues.put(KEY_PASSWORD, password);
return mDb.insert(DATABASE_TABLE, null, initialValues);
}
/**
* Delete the user with the given rowId
*
* @param rowId id of user to delete
* @return true if deleted, false otherwise
*/
public boolean deleteUser(long rowId) {
return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
}
/**
* Return a Cursor over the list of all users in the database
*
* @return Cursor over all users
*/
public Cursor fetchAllUsers() {
return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_USERNAME,
KEY_PASSWORD}, null, null, null, null, null);
}
/**
* Return a Cursor positioned at the user that matches the given rowId
*
* @param rowId id of user to retrieve
* @return Cursor positioned to matching user, if found
* @throws SQLException if note could not be found/retrieved
*/
public Cursor fetchUser(long rowId) throws SQLException {
Cursor mCursor =
mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
KEY_USERNAME, KEY_USERNAME}, KEY_ROWID + "=" + rowId, null,
null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
/**
* Update the user using the details provided. The user to be updated is
* specified using the rowId, and it is altered to use the username and password
* values passed in
*
* @param rowId id of user to update
* @param username value to set users username to
* @param password value to set users password to
* @return true if the user was successfully updated, false otherwise
*/
public boolean updateUser(long rowId, String username, String password) {
ContentValues args = new ContentValues();
args.put(KEY_USERNAME, username);
args.put(KEY_PASSWORD, password);
return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}
}
这是我的注册表单java 包com.NebulaNewsCo.gameofwin;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class Register extends Activity {
private EditText mUsernameText;
private EditText mPasswordText;
private Long mRowId;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mUsernameText = (EditText) findViewById(R.id.reg_user_edit);
mPasswordText = (EditText) findViewById(R.id.reg_pass_edit);
Button confirmButton = (Button) findViewById(R.id.reg_submit_btn);
mRowId = null;
Bundle extras = getIntent() .getExtras();
if (extras != null) {
String title = extras.getString(gowDbAdapter.KEY_USERNAME);
String body = extras.getString(gowDbAdapter.KEY_PASSWORD);
mRowId = extras.getLong(gowDbAdapter.KEY_ROWID);
if (title != null) {
mUsernameText.setText(title);
}
if (body != null) {
mPasswordText.setText(body);
}
}
confirmButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Bundle bundle = new Bundle();
bundle.putString(gowDbAdapter.KEY_USERNAME, mUsernameText.getText().toString());
bundle.putString(gowDbAdapter.KEY_PASSWORD, mPasswordText.getText().toString());
if (mRowId != null) {
bundle.putLong(gowDbAdapter.KEY_ROWID, mRowId);
}
Intent mIntent = new Intent();
mIntent.putExtras(bundle);
setResult(RESULT_OK, mIntent);
finish();
}
});
}
/** Called when the user clicks the Go Back button */
public void goBack(View view) {
Intent intent = new Intent(Register.this, Home.class);
startActivity(intent);
finish();
}
/** Called when the user clicks the Submit button */
public void regSubmit(View view) {
Intent intent = new Intent(this, RegisterComplete.class);
startActivity(intent);
finish();
}
}
当我在测试时打开注册活动时崩溃了。如果您需要更多信息，请告诉我。
编辑：
以下是错误日志：
04-06 13:58:59.102: E/Trace(4540): error opening trace file: No such file or directory (2)
04-06 13:58:59.540: I/dalvikvm-heap(4540): Grow heap (frag case) to 11.726MB for 5644816-byte allocation
04-06 13:58:59.842: I/dalvikvm-heap(4540): Grow heap (frag case) to 14.118MB for 2508816-byte allocation
04-06 13:59:00.417: W/MMUMapper(4540): fail to register MVA, unsupported format(0x5)
04-06 13:59:00.644: W/MMUMapper(4540): fail to register MVA, unsupported format(0x5)
04-06 13:59:00.977: W/MMUMapper(4540): fail to register MVA, unsupported format(0x5)
04-06 13:59:01.474: I/SurfaceTextureClient(4540): [0x51768fa8] frames:3, duration:1.008000, fps:2.975705
04-06 13:59:02.975: I/SurfaceTextureClient(4540): [0x51768fa8] frames:3, duration:1.500000, fps:1.999203
04-06 13:59:03.967: W/dalvikvm(4540): threadid=1: thread exiting with uncaught exception (group=0x40f3b908)
04-06 13:59:03.983: E/AndroidRuntime(4540): FATAL EXCEPTION: main
04-06 13:59:03.983: E/AndroidRuntime(4540): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.NebulaNewsCo.gameofwin/com.NebulaNewsCo.gameofwin.Register}: java.lang.NullPointerException
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2203)
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.app.ActivityThread.access$600(ActivityThread.java:150)
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1301)
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.os.Handler.dispatchMessage(Handler.java:99)
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.os.Looper.loop(Looper.java:153)
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.app.ActivityThread.main(ActivityThread.java:5006)
04-06 13:59:03.983: E/AndroidRuntime(4540): at java.lang.reflect.Method.invokeNative(Native Method)
04-06 13:59:03.983: E/AndroidRuntime(4540): at java.lang.reflect.Method.invoke(Method.java:511)
04-06 13:59:03.983: E/AndroidRuntime(4540): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
04-06 13:59:03.983: E/AndroidRuntime(4540): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
04-06 13:59:03.983: E/AndroidRuntime(4540): at dalvik.system.NativeStart.main(Native Method)
04-06 13:59:03.983: E/AndroidRuntime(4540): Caused by: java.lang.NullPointerException
04-06 13:59:03.983: E/AndroidRuntime(4540): at com.NebulaNewsCo.gameofwin.Register.onCreate(Register.java:39)
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.app.Activity.performCreate(Activity.java:5076)
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1083)
04-06 13:59:03.983: E/AndroidRuntime(4540): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2167)
04-06 13:59:03.983: E/AndroidRuntime(4540): ... 11 more
答案 0 :(得分：1)
打开log cat并找到错误。
答案 1 :(得分：0)
在日志中，Register.java的第39行包含您操作的某个null值。
在消息来源中，这似乎就是这条线
confirmButton.setOnClickListener(new View.OnClickListener() {
看起来confirmButton是null，导致NullPointerException被抛出，因为您尝试访问该对象。 findViewById返回null的原因是找不到请求的视图。
您的代码似乎没有设置任何内容视图（例如，使用setContentView），因此，您无法使用findViewById找到任何视图。