我正在尝试运行下面的代码。但它只返回我表中的第一个数据。我是Android开发的新手。
public String getStudentname(String table, String studid)
{
Cursor cursor=mDb.query(table, null, null, null, null, null, null);
if(cursor.getCount()<1) // UserName does Not Exist
{
cursor.close();
return "DOES NOT EXIST";
}
cursor.moveToFirst();
String studname= cursor.getString(cursor.getColumnIndex("StudentName"));
cursor.close();
return studname;
}
到目前为止我做了什么：
public String getStudentname(String table, String studid)
{
Cursor cursor=mDb.query(table, null, " _id=?", new String[]{studid},null, null, null);
if(cursor.getCount()<1) // UserName does Not Exist
{
cursor.close();
return "DOES NOT EXIST";
}
cursor.moveToFirst();
String studcourse= cursor.getString(cursor.getColumnIndex("StudentName"));
cursor.close();
return studname;
}
但它仍然无效。希望你能帮帮我。
这是logcat：
09-15 17:18:16.424: E/AndroidRuntime(20504): java.lang.RuntimeException:
Unable to resume activity {com.csu.eclassrecord/com.csu.eclassrecord.Student_Profile}:
java.lang.IllegalArgumentException: the bind value at index 1 is null
这是我的Student_Profile的完整代码：
public class Student_Profile extends Activity implements OnClickListener {
private LoginDataBaseAdapter loginDataBaseAdapter;
Bitmap image;
Bitmap bitmap;
String picture_location;
TextView b,c,d,e,f;
private static final int ACTIVITY_EDIT=1;
private StudentsDbAdapter studentsDbAdapter;
ImageView targetImage;
public static final String MyPREFERENCES = "MyPrefs" ;
ListView listv;
private String mRowId, studID;
SimpleCursorAdapter cursorAdapter;
Cursor cursor;
// String table;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.students_profile);
// create a instance of SQLite Database
loginDataBaseAdapter = new LoginDataBaseAdapter(this);
loginDataBaseAdapter=loginDataBaseAdapter.open();
studentsDbAdapter = new StudentsDbAdapter(this);
studentsDbAdapter.open();
b = (TextView) findViewById(R.id.studcourse);
// b.setText(course);
c = (TextView) findViewById(R.id.studyear);
// c.setText(year);
d = (TextView) findViewById(R.id.studnameview);
// d.setText(name);
e = (TextView) findViewById(R.id.studemail);
// e.setText(email);
f = (TextView) findViewById(R.id.studcontact);
// f.setText(contact);
targetImage=(ImageView) findViewById(R.id.studpic);
targetImage.setOnClickListener(new ImageView.OnClickListener(){
@Override
public void onClick(View arg0) {
Intent intent = new Intent(Intent.ACTION_PICK,
android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, 0);
}});
showpic();
}
private void setRowIdFromIntent() {
if (mRowId == null) {
Bundle extras = getIntent().getExtras();
mRowId = extras != null ? extras.getString(loginDataBaseAdapter.KEY_secName)
: null;
}
if (studID == null) {
Bundle extras = getIntent().getExtras();
studID = extras != null ? extras.getString(loginDataBaseAdapter.KEY_studID)
: null;
}
}
@Override
protected void onPause() {
super.onPause();
studentsDbAdapter.close();
loginDataBaseAdapter.close();
}
@Override
protected void onResume() {
super.onResume();
studentsDbAdapter.open();
setRowIdFromIntent();
populateFields();
}
private void populateFields() {
String name=studentsDbAdapter.getStudentname(mRowId, studID);
d.setText(name);
/** String course=studentsDbAdapter.getStudentcourse(mRowId, studID);
String year=studentsDbAdapter.getStudentYear(mRowId, studID);
String contact=studentsDbAdapter.getStudentContact(mRowId, studID);
String email=studentsDbAdapter.getStudentEmail(mRowId, studID);
b.setText(course);
c.setText(year);
e.setText(email);
f.setText(contact);
**/
}
@Override
public void onActivityResult( int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == Activity.RESULT_OK){
Uri targetUri = data.getData();
picture_location = targetUri.toString();
Bitmap bitmap;
try {
bitmap = BitmapFactory.decodeStream(this.getContentResolver().openInputStream(targetUri));
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
byte[] byteArray = stream.toByteArray();
loginDataBaseAdapter.insertPhoto(byteArray);
showpic();
}
catch (FileNotFoundException e){
e.printStackTrace();
}
}
}
public void showpic() {
LoginDataBaseAdapter db = loginDataBaseAdapter.open();
boolean emptytab = false;
boolean empty = db.checkPic(null, emptytab);
//Cursor cursor = loginDataBaseAdapter.fetchProfileImageFromDatabase();
if(empty==false)
{
Cursor cursor = loginDataBaseAdapter.fetchProfileImageFromDatabase();
cursor.moveToFirst();
byte[] data = cursor.getBlob(cursor.getColumnIndex("Path"));
ByteArrayInputStream imageStream = new ByteArrayInputStream(data);
Bitmap theImage = BitmapFactory.decodeStream(imageStream);
targetImage.setImageBitmap(theImage);
cursor.close();
}
}
@Override
public void onClick(View v) {
Intent intent;
switch (v.getId()) {
case R.id.nameview:
intent = new Intent(this.getApplication(), UpdateAccount.class);
startActivity(intent);
break;
default:
break;
}
}
public void onBackPressed() {
Intent i = new Intent(getApplicationContext(), Students_Show.class);
i.putExtra(loginDataBaseAdapter.KEY_secName, mRowId);
startActivityForResult(i, 1);
finish();
return;
}
}