我创建了一个包含ID，姓名，家庭，年龄，学生ID，学生电话号码的数据库。现在，我尝试通过搜索ID来检索学生的姓名和系列，然后使用游标适配器在自定义列表视图中显示检索到的数据，但我的代码不起作用。 请告诉我如何在列表视图中显示检索到的数据
这里我发布了我的代码：
DatabaseManager.java
const(
Stage1 FeeStage = 1
Stage2 FeeStage = 2
Stage3 FeeStage = 2
)
Student.java
package com.example.tempcursoradapter;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseManager extends SQLiteOpenHelper{
public DatabaseManager(Context context)
{
super(context,"myDB",null,1);
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
String query= "CREATE TABLE tbl_student ( "+
" ID INT PRIMARY KEY"+
" UNIQUE,"+
" Name VARCHAR( 50 ),"+
" Family VARCHAR( 50 ),"+
" Age INT,"+
" StudentNumber VARCHAR( 11 ),"+
" Tel VARCHAR( 15 )"+
" );";
db.execSQL(query);
}
@Override
public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS tbl_student");
onCreate(db);
}
public boolean addStudent (Student student)
{
boolean result;
try{
String query="INSERT INTO tbl_Student (ID,Name,Family,Age,StudentNumber,Tel) " +
"VALUES ("+student.ID+",'"+student.Name+"','"+student.Family+"',"+27+",'"
+student.stdNum+"','"+student.Tel+"')";
SQLiteDatabase db=this.getWritableDatabase();
db.execSQL(query);
db.close();
result = true;
}
catch(Exception e){
result=false;
}
return result;
}
public boolean updataStudent (Student student)
{
boolean result;
try{
String query ="UPDATE tbl_Student SET Name='"+student.Name+"',Family='"+student.Family+
"',Age="+student.age+",StudentNumber='"+student.stdNum+"',Tel='"+student.Tel+"'" +
" where ID = "+student.ID+"";
SQLiteDatabase db =this.getWritableDatabase();
db.execSQL(query);
db.close();
result =true;
}
catch (Exception e){
result= false;
}
return result;
}
public Cursor getStudent (int id)
{
String query ="SELECT Name,Family FROM tbl_Student";
SQLiteDatabase db=this.getReadableDatabase();
Cursor cursor =db.rawQuery(query, null);
return cursor;
}
public int getStudentCount()
{
int result=0;
String query="SELECT * FROM tbl_student";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor=db.rawQuery(query, null);
result=cursor.getCount();
db.close();
return result;
}
public boolean deleteStudent (int id)
{
boolean result;
try{
String query ="DELETE FROM tbl_student WHERE ID="+id;
SQLiteDatabase db=this.getWritableDatabase();
db.execSQL(query);
db.close();
result=true;
}
catch(Exception e)
{
result=false;
}
return result;
}
}
TodoCursorAdapter.java
package com.example.tempcursoradapter;
public class Student {
public int ID,age;
public String Name,Family,stdNum,Tel;
}
MainActivity.java
package com.example.tempcursoradapter;
import android.content.Context;
import android.database.Cursor;
import android.support.v4.widget.CursorAdapter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class TodoCursorAdapter extends CursorAdapter {
public TodoCursorAdapter(Context context, Cursor cursor, int flags) {
super(context, cursor, 0);
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
return LayoutInflater.from(context).inflate(R.layout.item_todo, parent, false);
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
// Find fields to populate in inflated template
TextView tvName = (TextView) view.findViewById(R.id.tvname);
TextView tvFamily = (TextView) view.findViewById(R.id.tvfamily);
// Extract properties from cursor
String body = cursor.getString(cursor.getColumnIndexOrThrow("Name"));
String priority = cursor.getString(cursor.getColumnIndexOrThrow("Family"));
// Populate fields with extracted properties
tvName.setText(body);
tvFamily.setText(String.valueOf(priority));
}
}
这是输出LogCat
package com.example.tempcursoradapter;
import android.R.integer;
import android.os.Bundle;
import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
public class MainActivity extends Activity {
ListView lv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv=(ListView) findViewById(R.id.listView1);
// add 10 sample data to database
final DatabaseManager db = new DatabaseManager(this);
for (int j = 0; j < 10; j++) {
Student student = new Student();
student.ID=j;
student.Name="name_"+String.valueOf(j);
student.Family="family_"+String.valueOf(j);
student.age=j;
student.stdNum="stdNum_"+String.valueOf(j);
student.Tel="telNum_"+String.valueOf(j);
db.addStudent(student);
}
// search for ID=1
// I didn't used a Edit Text for input for simplicity and I only search for ID=1
Cursor todoCursor = db.getStudent(1);
// I know this line is my code's problem. my code crash at this line!
TodoCursorAdapter todoAdapter = new TodoCursorAdapter(MainActivity.this, todoCursor,0);
lv.setAdapter(todoAdapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
感谢您的好意
我已经更改了我的表格，但它仍然崩溃。
02-27 12:28:54.129: E/Trace(6837): error opening trace file: No such file or directory (2)
02-27 12:28:55.258: D/dalvikvm(6837): GC_FOR_ALLOC freed 44K, 7% free 2555K/2720K, paused 44ms, total 50ms
02-27 12:28:55.268: I/dalvikvm-heap(6837): Grow heap (frag case) to 3.216MB for 635812-byte allocation
02-27 12:28:55.328: D/dalvikvm(6837): GC_FOR_ALLOC freed 2K, 6% free 3173K/3344K, paused 56ms, total 56ms
02-27 12:28:55.458: D/dalvikvm(6837): GC_CONCURRENT freed <1K, 5% free 3190K/3344K, paused 7ms+19ms, total 130ms
02-27 12:28:55.958: D/AndroidRuntime(6837): Shutting down VM
02-27 12:28:55.958: W/dalvikvm(6837): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
02-27 12:28:55.978: E/AndroidRuntime(6837): FATAL EXCEPTION: main
02-27 12:28:55.978: E/AndroidRuntime(6837): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tempcursoradapter/com.example.tempcursoradapter.MainActivity}: java.lang.IllegalArgumentException: column '_id' does not exist
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.app.ActivityThread.access$600(ActivityThread.java:141)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.os.Handler.dispatchMessage(Handler.java:99)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.os.Looper.loop(Looper.java:137)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.app.ActivityThread.main(ActivityThread.java:5041)
02-27 12:28:55.978: E/AndroidRuntime(6837): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 12:28:55.978: E/AndroidRuntime(6837): at java.lang.reflect.Method.invoke(Method.java:511)
02-27 12:28:55.978: E/AndroidRuntime(6837): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
02-27 12:28:55.978: E/AndroidRuntime(6837): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
02-27 12:28:55.978: E/AndroidRuntime(6837): at dalvik.system.NativeStart.main(Native Method)
02-27 12:28:55.978: E/AndroidRuntime(6837): Caused by: java.lang.IllegalArgumentException: column '_id' does not exist
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:303)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.support.v4.widget.CursorAdapter.init(CursorAdapter.java:174)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.support.v4.widget.CursorAdapter.<init>(CursorAdapter.java:151)
02-27 12:28:55.978: E/AndroidRuntime(6837): at com.example.tempcursoradapter.TodoCursorAdapter.<init>(TodoCursorAdapter.java:13)
02-27 12:28:55.978: E/AndroidRuntime(6837): at com.example.tempcursoradapter.MainActivity.onCreate(MainActivity.java:42)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.app.Activity.performCreate(Activity.java:5104)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
02-27 12:28:55.978: E/AndroidRuntime(6837): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
02-27 12:28:55.978: E/AndroidRuntime(6837): ... 11 more
输出LogCat
String query= "CREATE TABLE tbl_student ( "+
" _id integer PRIMARY KEY autoincrement," +
" ID INT "+
" UNIQUE,"+
" Name VARCHAR( 50 ),"+
" Family VARCHAR( 50 ),"+
" Age INT,"+
" StudentNumber VARCHAR( 11 ),"+
" Tel VARCHAR( 15 )"+
" );";
db.execSQL(query);
我也使用过这个命令，但我的问题是一样的
02-27 13:55:40.529: W/dalvikvm(9220): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
02-27 13:55:40.538: E/AndroidRuntime(9220): FATAL EXCEPTION: main
02-27 13:55:40.538: E/AndroidRuntime(9220): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tempcursoradapter/com.example.tempcursoradapter.MainActivity}: java.lang.IllegalArgumentException: column '_id' does not exist
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.app.ActivityThread.access$600(ActivityThread.java:141)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.os.Handler.dispatchMessage(Handler.java:99)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.os.Looper.loop(Looper.java:137)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.app.ActivityThread.main(ActivityThread.java:5041)
02-27 13:55:40.538: E/AndroidRuntime(9220): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 13:55:40.538: E/AndroidRuntime(9220): at java.lang.reflect.Method.invoke(Method.java:511)
02-27 13:55:40.538: E/AndroidRuntime(9220): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
02-27 13:55:40.538: E/AndroidRuntime(9220): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
02-27 13:55:40.538: E/AndroidRuntime(9220): at dalvik.system.NativeStart.main(Native Method)
02-27 13:55:40.538: E/AndroidRuntime(9220): Caused by: java.lang.IllegalArgumentException: column '_id' does not exist
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:303)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.support.v4.widget.CursorAdapter.init(CursorAdapter.java:174)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.support.v4.widget.CursorAdapter.<init>(CursorAdapter.java:122)
02-27 13:55:40.538: E/AndroidRuntime(9220): at com.example.tempcursoradapter.TodoCursorAdapter.<init>(TodoCursorAdapter.java:13)
02-27 13:55:40.538: E/AndroidRuntime(9220): at com.example.tempcursoradapter.MainActivity.onCreate(MainActivity.java:42)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.app.Activity.performCreate(Activity.java:5104)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
02-27 13:55:40.538: E/AndroidRuntime(9220): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
02-27 13:55:40.538: E/AndroidRuntime(9220): ... 11 more
02-27 14:00:40.689: I/Process(9220): Sending signal. PID: 9220 SIG: 9
答案 0 :(得分：1)
答案 1 :(得分：0)
问题是您的表"_id"
tbl_student
要使用CursorAdapter，您必须拥有＆＃34; _id＆＃34;表格中的列。 改变 -
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
String query= "CREATE TABLE tbl_student ( "+
" _id INT PRIMARY KEY"+
" UNIQUE,"+
" Name VARCHAR( 50 ),"+
" Family VARCHAR( 50 ),"+
" Age INT,"+
" StudentNumber VARCHAR( 11 ),"+
" Tel VARCHAR( 15 )"+
" );";
db.execSQL(query);
}
阅读this。
答案 2 :(得分：0)
除了将ID列重命名为_id之外，您还应该重写DatabaseManager方法：
public boolean addStudent(Student student) {
boolean result;
try {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("Name", student.Name);
contentValues.put("Family", student.Family);
// etc
db.insert("tbl_Student", null, contentValues);
db.close();
result = true;
} catch (Exception e) {
result = false;
}
return result;
}
public Cursor getStudent(int id) {
SQLiteDatabase db = this.getReadableDatabase();
return db.query("tbl_Student", null, "_id = ?", new String[]{String.valueOf(id)}, null, null, null);
}
您可以找到有用的指南here
答案 3 :(得分：0)
迟到派对，但是你的问题是：
public Cursor getStudent (int id)
{
String query ="SELECT Name,Family FROM tbl_Student";
SQLiteDatabase db=this.getReadableDatabase();
Cursor cursor =db.rawQuery(query, null);
return cursor;
}
更改为：
public Cursor getStudent (int id)
{
String query ="SELECT _id, Name, Family FROM tbl_Student";
SQLiteDatabase db=this.getReadableDatabase();
Cursor cursor =db.rawQuery(query, null);
return cursor;
}