我的程序有一个活动和一个数据库类。有一个用于从database.i中检索数据的按钮，用于显示textView中的字符串。但它没有得到。
FirstActivity.java
package example.showevent1;
import java.util.Calendar;
import android.os.Bundle;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v4.app.*;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.AdapterView.OnItemSelectedListener;
public class FirstActivity extends FragmentActivity implements OnItemSelectedListener {
/** Called when the activity is first created. */
classdbOpenHelper eventsData;
classdbOpenHelper eventsData1;
TextView userSelection;
Button okButton;
Button addButton;
Button change_date_but;
TextView date;
TextView show;
EditText edittext;
public static final int Date_dialog_id = 1;
private int mYear;
private int mMonth;
private int mDay;
private static final String[] items={"Yalahanka","Rajai nagar","Sivaji Nagar","Koramangala","RT Nagar", "Banashankari","Yashwanthpura","Hebbal"};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
okButton = (Button)findViewById(R.id.button2);
addButton = (Button)findViewById(R.id.button3);
change_date_but = (Button)findViewById(R.id.button1);
date = (TextView)findViewById(R.id.textView2);//KEY_DATE
userSelection=(TextView)findViewById(R.id.textView1);//KEY_DESC
edittext=(EditText)findViewById(R.id.editText1);//KEY_EVENT
show=(TextView)findViewById(R.id.textView5);
Spinner my_spin=(Spinner)findViewById(R.id.spinner1);
my_spin.setOnItemSelectedListener(this);
ArrayAdapter aa=new ArrayAdapter(this, android.R.layout.simple_spinner_item,items);
aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
my_spin.setAdapter(aa);
okButton.setOnClickListener(new clicker());
addButton.setOnClickListener(new getclicker());
eventsData = new classdbOpenHelper(this);
change_date_but.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
DatePickerDialog DPD = new DatePickerDialog(
FirstActivity.this, mDateSetListener, mYear, mMonth,mDay);
DPD.show();
}
});
final Calendar c = Calendar.getInstance();
mYear = c.get(Calendar.YEAR);
mMonth = c.get(Calendar.MONTH);
mDay = c.get(Calendar.DAY_OF_MONTH);
updateDisplay();
}
@Override
@Deprecated
protected void onPrepareDialog(int id, Dialog dialog) {
// TODO Auto-generated method stub
super.onPrepareDialog(id, dialog);
((DatePickerDialog) dialog).updateDate(mYear, mMonth, mDay);
}
private DatePickerDialog.OnDateSetListener mDateSetListener = new DatePickerDialog.OnDateSetListener() {
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
mYear = year;
mMonth = monthOfYear;
mDay = dayOfMonth;
updateDisplay();
}
};
private void updateDisplay() {
// TODO Auto-generated method stub
date.setText(new StringBuilder()
// Month is 0 based so add 1
.append(mMonth + 1).append("-").append(mDay).append("-")
.append(mYear));
}
@Override
public void onItemSelected(AdapterView<?> arg0, View arg1, int pos, long arg3) {
userSelection.setText(items[pos]);
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
userSelection.setText("");
}
class clicker implements Button.OnClickListener {
public void onClick(View v) {
String datevalue = date.getText().toString();
String Userselectvalue = userSelection.getText().toString();
String Userevent = edittext.getText().toString();
SQLiteDatabase db = eventsData.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(classdbOpenHelper.KEY_DESC, Userselectvalue);
cv.put(classdbOpenHelper.KEY_EVENT, Userevent);
cv.put(classdbOpenHelper.KEY_DATE,datevalue);
db.insert(classdbOpenHelper.DATABASE_TABLE, null, cv);
db.close();
}
public void onDestroy() {
eventsData.close();
}
}
class getclicker implements Button.OnClickListener {
public void onClick(View v) {
String datevalue = date.getText().toString();
String Userselectvalue = userSelection.getText().toString();
String showevent = eventsData.getContact(datevalue,Userselectvalue);
show.setText(showevent);
}
public void onDestroy() {
eventsData.close();
}
}
}
classdbOpenHelper.java
package example.showevent1;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.TextView;
public class classdbOpenHelper extends SQLiteOpenHelper {
public static final String KEY_ROWID = "id";
public static final String KEY_DESC = "countdesc";
public static final String KEY_EVENT = "countevent";
public static final String KEY_DATE = "countdate";
public static final String DATABASE_NAME= "countdb";
public static final String DATABASE_TABLE = "countable";
public static final int DATABASE_VERSION = 1;
public classdbOpenHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
/* db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT " +
//KEY_COUNTED + " INTEGER " +
KEY_DESC + " TEXT NOT NULL " +
KEY_DATE + " TEXT NOT NULL);"
); */
String CREATE_CONTACTS_TABLE = "CREATE TABLE " + DATABASE_TABLE + "("
+ KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_DESC + " TEXT, " + KEY_EVENT + " TEXT, " + KEY_DATE + " TEXT " + ")";
db.execSQL(CREATE_CONTACTS_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXITS " + DATABASE_TABLE);
onCreate(db);
}
public String getContact(String datevalue,String Userselectvalue)
{
String place = null;
String selection = classdbOpenHelper.KEY_DESC + " = 'Userselectvalue'"
+" AND " + classdbOpenHelper.KEY_DATE + " = 'datevalue'";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(classdbOpenHelper.DATABASE_TABLE,
new String[] {classdbOpenHelper.KEY_EVENT }, selection,
null, null, null, null);
if (cursor .getCount() > 0) {
cursor .moveToFirst();
do {
place = cursor.getString(0);
} while (cursor.moveToNext());
}
cursor.close();
return place;
}
}
activity_first.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:background="@color/color_1"
tools:context=".FirstActivity" >
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/spinner1"
android:layout_below="@+id/spinner1"
android:layout_marginTop="28dp"
android:background="#ffff99"
android:text="@string/dt"
android:textColor="#b22924" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/spinner1"
android:layout_alignParentTop="true"
android:layout_marginTop="31dp"
android:text="@string/select"
android:textAlignment="gravity"
android:textColor="#b22924"
android:textSize="20sp"
android:textStyle="bold" />
<Spinner
android:id="@+id/spinner1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/textView1"
android:layout_marginTop="36dp"
android:background="#ffff99"
android:textColor="#b22924"
android:fadingEdge=""/>
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button1"
android:layout_below="@+id/button1"
android:layout_marginTop="40dp"
android:background="#ffff99"
android:ems="10" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/editText1"
android:layout_alignBottom="@+id/editText1"
android:layout_alignParentRight="true"
android:text="@string/_add" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/button1"
android:layout_alignParentRight="true"
android:background="#ffff99"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView1"
android:layout_alignParentTop="true"
android:text="Select A Place" />
<TextView
android:id="@+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/button1"
android:layout_alignTop="@+id/button2"
android:text="Add Event" />
<Button
android:id="@+id/button3"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/editText1"
android:layout_below="@+id/button2"
android:layout_marginTop="27dp"
android:text="Show Event" />
<TextView
android:id="@+id/textView5"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="22dp"
android:background="#ffff99"
android:text="" />
</RelativeLayout>
的strings.xml
<?xml version="1.0" encoding="utf-8"?>
<resources xmlns:android="http://schemas.android.com/apk/res/android">
<string name="app_name">EVENTS</string>
<string name="action_settings">Settings</string>
<string name="select">SELECT A PLACE</string>
<color name="color_1">#ffcccccc</color>
<string name="dt">date</string>
<string name="_add">Add</string>
</resources>
答案 0 :(得分：0)
您的问题如下：您没有从数据库中获得任何结果：
修改以下行
String selection = classdbOpenHelper.KEY_DESC + " = 'Userselectvalue'" +" AND " + classdbOpenHelper.KEY_DATE + " = 'datevalue'";
到
String selection = classdbOpenHelper.KEY_DESC + " = '" + Userselectvalue + "'" + " AND " + classdbOpenHelper.KEY_DATE + " = '" + datevalue+ "'";
应该解决你的问题。
我建议你阅读一些教程：