我是Android应用程序开发的新手。我已经创建了包含用户名，密码和电子邮件的注册表单。这个值应该存储在sqlite数据库表中。从表中检索数据。
login.java 中的我创建了表格，并动态地将注册表单数据的值插入到表格中。 在 databsehelper.java 扩展中，databaseopenHelper类覆盖了oncreate和upgrade方法。这个类我在login.java中使用了这个类。
在 display.java 中，我将在成功注册详情中显示数据。
没有错误，但它会在模拟器上意外停止错误。 我将代码放在下面。
login.java
package rt.prj;
import java.util.Arrays;
import java.util.Locale;
import rt.prj.DatabaseHelper;
import android.app.Activity;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.Editable;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class realestatenew extends Activity {
/** Called when the activity is first created. */
public static final String DEBUG_TAG = "FullDatabase Log";
public static final int DB_version = 1;
//public static final String DB_name = "User.db";
public static final String TABLE_NAME = "tbl_users";
//public static final String TABLE_NAME = "tbl_temp";
//public static final String DB_name = "User_temp";
public static final String DB_name = "User";
public static final String CREATE_USER_TABLE = "CREATE TABLE"+TABLE_NAME+"(id INTEGER PRIMARY KEY AUTOINCREMENT, firstname TEXT,lastname TEXT, username TEXT, password TEXT, email TEXT);";
public static final String DROP_USER_TABLE = "DROP TABLE tbl_users;";
public DatabaseHelper database_helper;
public SQLiteDatabase database;
public SQLiteDatabase database_rd;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main1);
Button register=(Button)findViewById(R.id.Button01);
//private EditText text1;
//Registration database creation
createDataBase();
register.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
realestatenew login = new realestatenew();
Toast.makeText(login.getApplicationContext(),"In Helper executin onCreate()", Toast.LENGTH_SHORT).show();
String[] success = insertRecords();
if(success[0].equalsIgnoreCase("1"))
{
Intent mIntent = new Intent(realestatenew.this,DisplayUser.class);
mIntent.putExtra("username",success[1]);
mIntent.putExtra("password",success[2]);
mIntent.putExtra("email",success[3]);
startActivity(mIntent);
}
}
});
}
//database create function
void createDataBase()
{
if(Arrays.binarySearch(databaseList(), DB_name)>=0)
{
deleteDatabase(DB_name);
}
database_helper = new
DatabaseHelper(this.getApplicationContext(),DB_name,null,DB_version);
//database_helper.onCreate(database);
database = database_helper.getWritableDatabase();
database.setLocale(Locale.getDefault());
// Set the locale
database.setLockingEnabled(true);
database_rd = database_helper.getReadableDatabase();
Toast.makeText(this, "created database",
Toast.LENGTH_SHORT).show();
/*
database =
openOrCreateDatabase(DB_name,SQLiteDatabase.CREATE_IF_NECESSARY,
null);
database.setLocale(Locale.getDefault()); // Set the locale
database.setLockingEnabled(true); // SQLiteDatabase is made
thread-safe by using locks around critical sections.
database.setVersion(1);
database.execSQL(CREATE_USER_TABLE);
*/
}
// data insertion
String[] insertRecords()
{
Toast.makeText(this,"In insertrecords",
Toast.LENGTH_SHORT).show();
//database.openDatabase(DB_name,database.create(factory),ACCESSIBILITY_SERVICE);
final EditText username = (EditText) findViewById(R.id.EditText01);
final EditText password= (EditText) findViewById(R.id.EditText02);
final EditText email= (EditText) findViewById(R.id.EditText04);
Long newUserID = 0l;
String uname = username.getText().toString();
String pwd = password.getText().toString();
String emailid = email.getText().toString();
ContentValues values = new ContentValues();
values.put("username",uname);
values.put("password",pwd);
values.put("email",emailid);
//StringBuilder info = new StringBuilder();
String[] info = new String[10];
database.beginTransaction();
try
{
Toast.makeText(this,"Before calling inserting values",
Toast.LENGTH_SHORT).show();
newUserID = database.insertOrThrow(TABLE_NAME, null, values);
Toast.makeText(this,"After calling inserting values",
Toast.LENGTH_SHORT).show();
info[0] = newUserID.toString();
info[1] = uname;
info[2] = pwd;
info[3] = emailid;
System.out.println(newUserID);
Toast.makeText(this, newUserID.toString(),
Toast.LENGTH_SHORT).show();
Cursor c = database_rd.query(TABLE_NAME, null, null, null, null,null,null);
LogCursorInfo(c);
c.close();
}
catch(Exception e)
{
//Transaction failed;
e.printStackTrace();
}
finally
{
database.endTransaction();
database.close();
}
return info;
}
public void LogCursorInfo(Cursor c)
{
Log.i(DEBUG_TAG, "*** Cursor Begin *** " + " Results:" +
c.getCount() + " Columns: " + c.getColumnCount());
// Print column names
String rowHeaders = "|| ";
for (int i = 0; i < c.getColumnCount(); i++) {
rowHeaders = rowHeaders.concat(c.getColumnName(i) +"||");
}
Log.i(DEBUG_TAG, "COLUMNS " + rowHeaders);
//Integer rows = c.getCount();
//Toast.makeText(this, rows.toString(),
// Toast.LENGTH_SHORT).show();
// Print records
c.moveToFirst();
while (c.isAfterLast() == false) {
String rowResults = "|| ";
for (int i = 0; i < c.getColumnCount(); i++) {
rowResults = rowResults.concat(c.getString(i) +
" || ");
}
Log.i(DEBUG_TAG, "Row " + c.getPosition() + ": " +
rowResults);
Toast.makeText(this, rowResults.toString(),
Toast.LENGTH_SHORT).show();
//Toast.makeText(this, "In LogCursorInfo",
// Toast.LENGTH_SHORT).show();
c.moveToNext();
}
Log.i(DEBUG_TAG, "*** Cursor End ***");
}
}
databasehelper.java
package rt.prj;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.widget.Toast;
public class DatabaseHelper extends SQLiteOpenHelper
{
public static final int DB_version = 1;
public static final String DB_name = "realestate.db";
public SQLiteDatabase database;
public static final String TABLE_NAME = "tbl_users";
//public static final String TABLE_NAME = "tbl_temp";
public static final String CREATE_USER_TABLE = "CREATE TABLE"+TABLE_NAME+"(id INTEGER PRIMARY KEY AUTOINCREMENT, firstname TEXT,lastname TEXT, username TEXT, password TEXT, email TEXT);";
realestatenew login = new realestatenew();
public DatabaseHelper(Context context, String name, CursorFactory
factory,int version)
{
super(context, DB_name, factory,DB_version);
// TODO Auto-generated constructor stub
}
public void onCreate(SQLiteDatabase db)
{
Toast.makeText(login.getApplicationContext(),"In Helper executingonCreate()", Toast.LENGTH_SHORT).show();
// Create the table
db.execSQL("DROP TABLE IF EXISTS tbl_users");
db.execSQL(CREATE_USER_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Housekeeping here.
// Implement how "move" your application data during an upgrade of schema versions
// There is no ALTER TABLE command in SQLite, so this generally involves
// CREATING a new table, moving data if possible, or deleting the old data and starting fresh
// Your call.
//db.execSQL("DROP TABLE IF EXISTS tbl_users");
//onCreate(database);
}
@Override
public void onOpen(SQLiteDatabase db) {
super.onOpen(db);
}
}
display.java
package rt.prj;
//import java.util.Locale;
import android.app.Activity;
//import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.TypedValue;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import rt.prj.*;
public class DisplayUser extends Activity
{
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
//setContentView(R.layout.userinfo);
final String DB_name = "realestate.db";
final String TABLE_NAME = "tbl_users";
final int DB_version = 1;
//final DatabaseHelper database_helper;
//final SQLiteDatabase database_wr;
/*
database =
openOrCreateDatabase(DB_name,SQLiteDatabase.CREATE_IF_NECESSARY,
null);
database.setLocale(Locale.getDefault()); // Set the locale
database.setLockingEnabled(true); // SQLiteDatabase is made
thread-safe by using locks around critical sections.
database.setVersion(1);
if(database.isOpen())
{
Toast.makeText(this, "Yes database is open",
Toast.LENGTH_SHORT).show();
}
if(database.isDbLockedByCurrentThread())
{
Toast.makeText(this, "Yes database is locked",
Toast.LENGTH_SHORT).show();
}
Cursor c = database.query(TABLE_NAME, null, null, null, null,
null,null);
LogIn login = new LogIn();
login.LogCursorInfo(c);
c.close();
*/
//LogIn login = new LogIn();
//database_wr = login.database_helper.getWritableDatabase();
String uname= getIntent().getStringExtra("username");
String pwd= getIntent().getStringExtra("password");
String email= getIntent().getStringExtra("email");
Toast.makeText(this, uname, Toast.LENGTH_SHORT).show();
View infoPanel = _createInfoPanel(uname,pwd,email);
setContentView(infoPanel);
}
public View _createInfoPanel(String uname,String pwd,String
email)
{
LinearLayout panel = new LinearLayout(this);
panel.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.FILL_PARENT));
panel.setOrientation(LinearLayout.VERTICAL);
// user id
TextView Welcome = new TextView(this);
Welcome.setText("Welcome "+uname);
Welcome.setTextSize(TypedValue.COMPLEX_UNIT_SP, 14f);
Welcome.setLayoutParams(new
LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
TextView UserName = new TextView(this);
UserName.setText("Username:"+uname);
UserName.setTextSize(TypedValue.COMPLEX_UNIT_SP, 14f);
UserName.setLayoutParams(new
LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
TextView pass = new TextView(this);
pass.setText("password:"+pwd);
pass.setTextSize(TypedValue.COMPLEX_UNIT_SP, 14f);
pass.setLayoutParams(new
LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
TextView Email = new TextView(this);
Email.setText("E-mailID:"+email);
Email.setTextSize(TypedValue.COMPLEX_UNIT_SP, 14f);
Email.setLayoutParams(new
LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
panel.addView(Welcome);
panel.addView(UserName);
panel.addView(pass);
panel.addView(Email);
return panel;
}
}
答案 0 :(得分：4)
不确定为什么会发生这种情况并且我无法真正阅读代码，因为它的格式不正确，但是如果你想要存储像某些文本字符串一样简单的东西，你真的应该使用SharedPreferences。使用SharedPreferences，您可以在大约5行代码中存储和检索数据。
final SharedPreferences prefs = context.getSharedPreferences();
Editor editor = prefs.edit();
editor.putString("email", email);
editor.putString("username", username);
editor.putString("password", password);
editor.commit();
email = prefs.getString("email");