我在制作 SQLite 版本时遇到问题，基本上，错误是 java.lang.NumberFormatException，我在我的数据中制作了 Long.parseLong，但我不知道为什么程序继续向我发送该错误，这是我的第一个代码下一节课:
public class SQLiteActivity extends Activity implements OnClickListener {
/** Called when the activity is first created. */
EditText ecoursename, etopic, ecourse_description, elength, erating, esearch;
Button insert, view, search, edit, delete;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ecoursename = (EditText) findViewById(R.id.cName);
etopic = (EditText) findViewById(R.id.cTopic);
ecourse_description= (EditText) findViewById(R.id.cDescription);
elength= (EditText) findViewById(R.id.cLength);
erating= (EditText) findViewById(R.id.cRating);
esearch = (EditText) findViewById(R.id.etSearch);
insert = (Button) findViewById(R.id.btInsert);
view = (Button) findViewById(R.id.btView);
search = (Button) findViewById(R.id.btSearch);
edit = (Button) findViewById(R.id.btEdit);
delete = (Button) findViewById(R.id.btDelete);
search.setOnClickListener(this);
edit.setOnClickListener(this);
delete.setOnClickListener(this);
insert.setOnClickListener(this);
view.setOnClickListener(this);
}
public void onClick(View v) {
//TODO Auto-generated method stub
switch (v.getId()){
case R.id.btInsert:
boolean works = true;
try{
String course_name = ecoursename.getText().toString();
String topic = etopic.getText().toString();
String course_description = ecourse_description.getText().toString();
String length = elength.getText().toString();
String rating = erating.getText().toString();
ecoursename.setText("");
etopic.setText("");
ecourse_description.setText("");
elength.setText("");
erating.setText("");
DBAdapter entry = new DBAdapter (SQLiteActivity.this);
entry.open();
entry.createEntry(course_name, topic, course_description, length, rating);
entry.close();
}catch(Exception e){
works = false;
String error = e.toString();
Dialog d = new Dialog(this);
d.setTitle("Dont Works");
TextView tv = new TextView(this);
tv.setText(error);
d.setContentView(tv);
d.show();
}finally{
if(works){
// make click says inserted text
Dialog d = new Dialog(this);
d.setTitle("Works?");
TextView tv = new TextView(this);
tv.setText("is Working");
d.setContentView(tv);
d.show();
}
}
break;
case R.id.btView:
Intent i = new Intent("com.sqlite.base.data.SQLVista");
startActivity(i);
break;
case R.id.btSearch:
String s = esearch.getText().toString();
Long ls = Long.parseLong(s);
DBAdapter dbase= new DBAdapter(this);
try{
dbase.open();
}catch(Exception e){
e.printStackTrace();
}
String bN = dbase.getN(ls);
String bT = dbase.getT(ls);
String bD = dbase.getD(ls);
String bL = dbase.getL(ls);
String bR = dbase.getR(ls);
dbase.close();
ecoursename.setText(bN);
etopic.setText(bT);
ecourse_description.setText(bD);
elength.setText(bL);
erating.setText(bR);
break;
case R.id.btEdit:
try{
String eCo = ecoursename.getText().toString();
String eTo = etopic.getText().toString();
String eDe = ecourse_description.getText().toString();
String eLe = elength.getText().toString();
String eRa = erating.getText().toString();
String eRow = esearch.getText().toString();
long eRowl = Long.parseLong(eRow);
DBAdapter edit = new DBAdapter(this);
edit.open();
edit.edit(eRowl, eCo, eTo, eDe, eLe, eRa);
edit.close();
}catch(Exception e) {
String error = e.toString();
Dialog d = new Dialog(this);
d.setTitle("Dont Works!");
TextView tv = new TextView(this);
tv.setText(error);
d.setContentView(tv);
d.show();
}
break;
case R.id.btDelete:
break;
}
}
}
我的 DBAdapter 类:
public class DBAdapter {
public static final String ID_ROW = "_id";
public static final String ID_COURSENAME = "course_name";
public static final String ID_TOPIC = "topic";
public static final String ID_DESCRIPTION = "course_description";
public static final String ID_LENGTH = "length";
public static final String ID_RATING = "rating";
private static final String N_DB = "Clases";
private static final String N_TABLE = "Courses";
private static final int VERSION_DB = 1;
private DBHelper nHelper;
private final Context nContext;
private SQLiteDatabase nDB;
private static class DBHelper extends SQLiteOpenHelper{
public DBHelper(Context context) {
super(context, N_DB, null, VERSION_DB);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(" CREATE TABLE " + N_TABLE + "(" + ID_ROW + " INTEGER PRIMARY KEY AUTOINCREMENT, " + ID_COURSENAME + " TEXT NOT NULL, " + ID_TOPIC + " TEXT NOT NULL, " + ID_DESCRIPTION + " TEXT NOT NULL, " + ID_LENGTH + " TEXT NOT NULL, " + ID_RATING + " TEXT NOT NULL);"
);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS " + N_TABLE);
onCreate(db);
}
}
public DBAdapter (Context c){
nContext = c;
}
public DBAdapter open() throws SQLException{
nHelper = new DBHelper(nContext);
nDB = nHelper.getWritableDatabase();
return this;
}
public void close() {
// TODO Auto-generated method stub
nHelper.close();
}
public long createEntry(String course_name, String topic, String course_description, String length, String rating ) {
// TODO Auto-generated method stub
//insert data
ContentValues cv = new ContentValues();
cv.put(ID_COURSENAME, course_name);
cv.put(ID_TOPIC, topic);
cv.put(ID_DESCRIPTION, course_description);
cv.put(ID_LENGTH, length);
cv.put(ID_RATING, rating);
//return content in table
return nDB.insert(N_TABLE, null, cv);
}
public String receive() {
// TODO Auto-generated method stub
String[] columns = new String[]{ID_ROW, ID_COURSENAME, ID_TOPIC, ID_DESCRIPTION, ID_LENGTH, ID_RATING};
Cursor c = nDB.query(N_TABLE, columns, null, null, null, null, null);
String result = "";
int iRow = c.getColumnIndex(ID_ROW);
int cName = c.getColumnIndex(ID_COURSENAME);
int cTopic = c.getColumnIndex(ID_TOPIC);
int cDescription = c.getColumnIndex(ID_DESCRIPTION);
int cLength = c.getColumnIndex(ID_LENGTH);
int cRating = c.getColumnIndex(ID_RATING);
//loop
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result = result + c.getString(iRow) + " " + c.getString(cName) + " " + c.getString(cTopic) + " " + c.getString(cDescription) + " " + c.getString(cLength) + " " + c.getString(cRating) + "\n ";
}
return result;
}
public String getN(Long ls) {
// TODO Auto-generated method stub
String[] columns = new String[]{ID_ROW, ID_COURSENAME, ID_TOPIC, ID_DESCRIPTION, ID_LENGTH, ID_RATING};
Cursor c =nDB.query(N_TABLE, columns, ID_ROW + "=" + ls, null, null, null, null);
if(c != null){
c.moveToFirst();
String ns = c.getString(1);
return ns;
}
return null;
}
public String getT(Long ls) {
// TODO Auto-generated method stub
String[] columns = new String[]{ID_ROW, ID_COURSENAME, ID_TOPIC, ID_DESCRIPTION, ID_LENGTH, ID_RATING};
Cursor c =nDB.query(N_TABLE, columns, ID_ROW + "=" + ls, null, null, null, null);
if(c != null){
c.moveToFirst();
String ts = c.getString(2);
return ts;
}
return null;
}
public String getD(Long ls) {
// TODO Auto-generated method stub
String[] columns = new String[]{ID_ROW, ID_COURSENAME, ID_TOPIC, ID_DESCRIPTION, ID_LENGTH, ID_RATING};
Cursor c =nDB.query(N_TABLE, columns, ID_ROW + "=" + ls, null, null, null, null);
if(c != null){
c.moveToFirst();
String nd = c.getString(3);
return nd;
}
return null;
}
public String getL(Long ls) {
// TODO Auto-generated method stub
String[] columns = new String[]{ID_ROW, ID_COURSENAME, ID_TOPIC, ID_DESCRIPTION, ID_LENGTH, ID_RATING};
Cursor c =nDB.query(N_TABLE, columns, ID_ROW + "=" + ls, null, null, null, null);
if(c != null){
c.moveToFirst();
String nl = c.getString(4);
return nl;
}
return null;
}
public String getR(Long ls) {
// TODO Auto-generated method stub
String[] columns = new String[]{ID_ROW, ID_COURSENAME, ID_TOPIC, ID_DESCRIPTION, ID_LENGTH, ID_RATING};
Cursor c =nDB.query(N_TABLE, columns, ID_ROW + "=" + ls, null, null, null, null);
if(c != null){
c.moveToFirst();
String nr = c.getString(5);
return nr;
}
return null;
}
public void edit(long eRowl, String eCo, String eTo, String eDe,
String eLe, String eRa) throws SQLException {
// TODO Auto-generated method stub
ContentValues cvEdit = new ContentValues();
cvEdit.put(ID_COURSENAME, eCo);
cvEdit.put(ID_TOPIC, eTo);
cvEdit.put(ID_DESCRIPTION, eDe);
cvEdit.put(ID_LENGTH, eLe);
cvEdit.put(ID_RATING, eRa);
nDB.update(N_TABLE, cvEdit, ID_ROW + "=" + eRowl, null);
}}
非常感谢您的帮助
最佳答案
感谢您的截图。请您改进您的代码:
}catch(Exception e) {
String error = e.getMessage(); //instead of String error = e.toString();
...
所以我们可以看到实际原因。 你能把“不起作用”对话框调大吗？我认为某些文本正在被修剪。
我相信您正在尝试解析一个空字符串“”。
关于android - 字符串值的 java.lang.NumberFormatException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/9245085/