EditarCliente.class

package com.example.basedatosprueba;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class EditarCliente extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_editar_cliente);

        final BaseDatos bd = new BaseDatos(this);
        final SQLiteDatabase sql = bd.getWritableDatabase();
        final String[] i = {getIntent().getExtras().getString("Id")};
        String name="", apel="", id="";
        Cursor cursor = sql.rawQuery("select _id , nombre, apellidos from clientes where _id = ?", i);
        final EditText editnombre = (EditText)findViewById(R.id.editText1);
        final EditText editapell = (EditText)findViewById(R.id.editText2);
        final EditText editID = (EditText)findViewById(R.id.editText3);
        Button btnGuardar = (Button)findViewById(R.id.button1);
        Button btnCancel = (Button)findViewById(R.id.button2);

        if(cursor.moveToFirst()){
            id = (cursor.getString(cursor.getColumnIndex("_id")));
            name = (cursor.getString(cursor.getColumnIndex("Nombre")));
            apel = (cursor.getString(cursor.getColumnIndex("Apellidos")));
        }

        editID.setText(id);
        editnombre.setText(name);
        editapell.setText(apel);

        btnCancel.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                // Cierra al darle a cancelar
                setResult(RESULT_CANCELED);
                finish();
            }
        });

        if(!i[0].equalsIgnoreCase("-1")){
            btnGuardar.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {
                    // Guarda los cambios
                    String[] datos = {editnombre.getText().toString(), editapell.getText().toString(), i[0]};
                    String strUpdate = "update clientes set nombre = '"+datos[0]+"', apellidos ='"+datos[1]+"' where _id = '"+datos[2]+"'";
                    sql.execSQL(strUpdate);
                    setResult(RESULT_OK);
                    finish();
                }
            });
        }
        else if(i[0].equalsIgnoreCase("-1")){
            btnGuardar.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {
                    String[] datos = {editnombre.getText().toString(), editapell.getText().toString(), editID.getText().toString()};
                    String strInsert = "insert into clientes (nombre, apellidos) values('"+datos[0]+"','"+datos[1]+"')";
                    sql.execSQL(strInsert);
                    setResult(RESULT_OK);
                    finish();
                }
            });
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.editar_cliente, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}