Bom, estou aprendendo a manipular banco de dados no Android, mas ao rodar minha aplicação, da este erro
03-16 21:21:05.617: D/AndroidRuntime(378): Shutting down VM
03-16 21:21:05.617: W/dalvikvm(378): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
03-16 21:21:05.627: E/AndroidRuntime(378): FATAL EXCEPTION: main
03-16 21:21:05.627: E/AndroidRuntime(378): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.propriocap14/com.example.propriocap14.Principal}: java.lang.NullPointerException
03-16 21:21:05.627: E/AndroidRuntime(378): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
03-16 21:21:05.627: E/AndroidRuntime(378): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
03-16 21:21:05.627: E/AndroidRuntime(378): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
03-16 21:21:05.627: E/AndroidRuntime(378): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
03-16 21:21:05.627: E/AndroidRuntime(378): at android.os.Handler.dispatchMessage(Handler.java:99)
03-16 21:21:05.627: E/AndroidRuntime(378): at android.os.Looper.loop(Looper.java:123)
03-16 21:21:05.627: E/AndroidRuntime(378): at android.app.ActivityThread.main(ActivityThread.java:4627)
03-16 21:21:05.627: E/AndroidRuntime(378): at java.lang.reflect.Method.invokeNative(Native Method)
03-16 21:21:05.627: E/AndroidRuntime(378): at java.lang.reflect.Method.invoke(Method.java:521)
03-16 21:21:05.627: E/AndroidRuntime(378): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
03-16 21:21:05.627: E/AndroidRuntime(378): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
03-16 21:21:05.627: E/AndroidRuntime(378): at dalvik.system.NativeStart.main(Native Method)
03-16 21:21:05.627: E/AndroidRuntime(378): Caused by: java.lang.NullPointerException
03-16 21:21:05.627: E/AndroidRuntime(378): at com.example.propriocap14.Principal.onCreate(Principal.java:33)
03-16 21:21:05.627: E/AndroidRuntime(378): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-16 21:21:05.627: E/AndroidRuntime(378): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
03-16 21:21:05.627: E/AndroidRuntime(378): ... 11 moreo codigo da aplicação em si
package com.example.propriocap14;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
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 Principal extends Activity {
private String nome;
private String sobrenome;
private static final String NOME_TABELA="loterica";
private static final String NOME_BANCO="usuarios";
private static final String[] colunas=new String[] {"id","nome","sobrenome"};
private Context ctx;
private static final String CATEGORIA="Livro";
protected SQLiteDatabase bd;
@Override
public void onCreate(Bundle icicle){
super.onCreate(icicle);
setContentView(R.layout.principal_loterica);
Log.i(CATEGORIA,"Até aqui tudo bem");
//abre o banco de dados
bd=ctx.openOrCreateDatabase(NOME_BANCO, MODE_PRIVATE, null);
//seta componentes view
Button btProcurar=(Button) findViewById(R.id.btProcurar);
btProcurar.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
// TODO Auto-generated method stub
EditText campoProcurar=(EditText) findViewById(R.id.campoNome);
nome=campoProcurar.getText().toString();
sobrenome=buscaSobrenome();
if (sobrenome != null){
TextView textoNome=(TextView) findViewById(R.id.textoNome);
textoNome.setText(nome);
TextView textoSobrenome=(TextView)findViewById(R.id.textoSobrenome);
textoSobrenome.setText(sobrenome);
} else {
Toast.makeText(Principal.this,"Nome não encontrado",Toast.LENGTH_SHORT).show();
}
}
});
}
protected String buscaSobrenome(){
String sobrenomeEncontrado=null;
Cursor cursor=bd.query(NOME_TABELA,colunas,"nome=?",new String[]{nome},null,null,null);
if(cursor.getCount()>0){
cursor.moveToFirst();
sobrenomeEncontrado=cursor.getString(2);
}
return sobrenomeEncontrado;
}
}