Android数据库帮助(如何添加删除按钮)
我一直在关注Commonware的DataAbse教程,这是午餐列表示例,但是我想知道如何添加删除按钮,以便在午餐项目创建后删除它 我四处搜索,找到了这个答案,但我不知道如何实现它,请有人告诉我如何实现 将delete()方法添加到RestaurantHelper类并从 DetailForm活动上的选项菜单项 谢谢 露西 javaAndroid数据库帮助(如何添加删除按钮),android,database,sqlite,Android,Database,Sqlite,我一直在关注Commonware的DataAbse教程,这是午餐列表示例,但是我想知道如何添加删除按钮,以便在午餐项目创建后删除它 我四处搜索,找到了这个答案,但我不知道如何实现它,请有人告诉我如何实现 将delete()方法添加到RestaurantHelper类并从 DetailForm活动上的选项菜单项 谢谢 露西 java import android.content.Context; import android.content.ContentValues; import androi
import android.content.Context;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteQueryBuilder;
class RestaurantHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME="Lunchlist.db";
private static final int SCHEMA_VERSION=1;
public RestaurantHelper(Context context) {
super(context, DATABASE_NAME, null, SCHEMA_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE restaurants (_id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, address TEXT, type TEXT, notes TEXT);");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// no-op, since will not be called until 2nd schema
// version exists
}
public Cursor getAll() {
return(getReadableDatabase()
.rawQuery("SELECT _id, name, address, type, notes FROM restaurants ORDER BY name",
null));
}
public void insert(String name, String address,
String type, String notes) {
ContentValues cv=new ContentValues();
cv.put("name", name);
cv.put("address", address);
cv.put("type", type);
cv.put("notes", notes);
getWritableDatabase().insert("restaurants", "name", cv);
}
public String getName(Cursor c) {
return(c.getString(1));
}
public String getAddress(Cursor c) {
return(c.getString(2));
}
public String getType(Cursor c) {
return(c.getString(3));
}
public String getNotes(Cursor c) {
return(c.getString(4));
}
}
午餐列表.java
package apt.tutorial;
import android.app.TabActivity;
import android.content.Context;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.LayoutInflater;
import android.widget.AdapterView;
import android.widget.CursorAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.RadioGroup;
import android.widget.TabHost;
import android.widget.TextView;
public class LunchList extends TabActivity {
Cursor model=null;
RestaurantAdapter adapter=null;
EditText name=null;
EditText address=null;
EditText notes=null;
RadioGroup types=null;
RestaurantHelper helper=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
helper=new RestaurantHelper(this);
name=(EditText)findViewById(R.id.name);
address=(EditText)findViewById(R.id.addr);
notes=(EditText)findViewById(R.id.notes);
types=(RadioGroup)findViewById(R.id.types);
address.setVisibility(View.GONE);
notes.setVisibility(View.GONE);
Button save=(Button)findViewById(R.id.save);
save.setOnClickListener(onSave);
ListView list=(ListView)findViewById(R.id.restaurants);
model=helper.getAll();
startManagingCursor(model);
adapter=new RestaurantAdapter(model);
list.setAdapter(adapter);
TabHost.TabSpec spec=getTabHost().newTabSpec("tag1");
spec.setContent(R.id.restaurants);
spec.setIndicator("My Reasons", getResources()
.getDrawable(R.drawable.list));
getTabHost().addTab(spec);
spec=getTabHost().newTabSpec("tag2");
spec.setContent(R.id.details);
spec.setIndicator("Add Reason", getResources()
.getDrawable(R.drawable.restaurant));
getTabHost().addTab(spec);
getTabHost().setCurrentTab(0);
list.setOnItemClickListener(onListClick);
}
@Override
public void onDestroy() {
super.onDestroy();
helper.close();
}
private View.OnClickListener onSave=new View.OnClickListener() {
public void onClick(View v) {
String type=null;
switch (types.getCheckedRadioButtonId()) {
case R.id.sit_down:
type="sit_down";
break;
case R.id.take_out:
type="take_out";
break;
case R.id.delivery:
type="delivery";
break;
}
helper.insert(name.getText().toString(),
address.getText().toString(), type,
notes.getText().toString());
model.requery();
}
};
private AdapterView.OnItemClickListener onListClick=new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent,
View view, int position,
long id) {
model.moveToPosition(position);
name.setText(helper.getName(model));
address.setText(helper.getAddress(model));
notes.setText(helper.getNotes(model));
if (helper.getType(model).equals("sit_down")) {
types.check(R.id.sit_down);
}
else if (helper.getType(model).equals("take_out")) {
types.check(R.id.take_out);
}
else {
types.check(R.id.delivery);
}
getTabHost().setCurrentTab(1);
}
};
class RestaurantAdapter extends CursorAdapter {
RestaurantAdapter(Cursor c) {
super(LunchList.this, c);
}
@Override
public void bindView(View row, Context ctxt,
Cursor c) {
RestaurantHolder holder=(RestaurantHolder)row.getTag();
holder.populateFrom(c, helper);
}
@Override
public View newView(Context ctxt, Cursor c,
ViewGroup parent) {
LayoutInflater inflater=getLayoutInflater();
View row=inflater.inflate(R.layout.row, parent, false);
RestaurantHolder holder=new RestaurantHolder(row);
row.setTag(holder);
return(row);
}
}
static class RestaurantHolder {
private TextView name=null;
private TextView address=null;
private ImageView icon=null;
RestaurantHolder(View row) {
name=(TextView)row.findViewById(R.id.title);
address=(TextView)row.findViewById(R.id.address);
icon=(ImageView)row.findViewById(R.id.icon);
}
void populateFrom(Cursor c, RestaurantHelper helper) {
name.setText(helper.getName(c));
address.setText(helper.getAddress(c));
if (helper.getType(c).equals("sit_down")) {
icon.setImageResource(R.drawable.ball_red);
}
else if (helper.getType(c).equals("take_out")) {
icon.setImageResource(R.drawable.ball_yellow);
}
else {
icon.setImageResource(R.drawable.ball_green);
}
}
}
}
package-apt.tutorial;
导入android.app.TabActivity;
导入android.content.Context;
导入android.database.Cursor;
导入android.os.Bundle;
导入android.view.view;
导入android.view.ViewGroup;
导入android.view.LayoutInflater;
导入android.widget.AdapterView;
导入android.widget.CursorAdapter;
导入android.widget.Button;
导入android.widget.EditText;
导入android.widget.ImageView;
导入android.widget.ListView;
导入android.widget.RadioGroup;
导入android.widget.TabHost;
导入android.widget.TextView;
公共类午餐列表扩展了TabActivity{
游标模型=空;
RestaurantAdapter适配器=空;
EditText name=null;
编辑文本地址=空;
EditText注释=空;
射线组类型=空;
RestaurantHelper helper=null;
@凌驾
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
助手=新餐厅服务员(此);
name=(EditText)findViewById(R.id.name);
地址=(EditText)findViewById(R.id.addr);
notes=(EditText)findViewById(R.id.notes);
类型=(放射组)findViewById(R.id.types);
地址.setVisibility(View.GONE);
notes.setVisibility(View.GONE);
按钮保存=(按钮)findViewById(R.id.save);
save.setOnClickListener(onSave);
ListView列表=(ListView)findViewById(R.id.restaurants);
model=helper.getAll();
开始管理光标(模型);
适配器=新餐厅适配器(型号);
list.setAdapter(适配器);
TabHost.TabSpec spec=getTabHost().newTabSpec(“tag1”);
规格设置内容(R.id.1);
spec.setIndicator(“我的理由”,getResources()
.getDrawable(R.drawable.list));
getTabHost().addTab(规范);
spec=getTabHost().newTabSpec(“tag2”);
规格设置内容(R.id.详细信息);
spec.setIndicator(“添加原因”,getResources())
.getDrawable(R.drawable.restaurant));
getTabHost().addTab(规范);
getTabHost().setCurrentTab(0);
list.setOnItemClickListener(onListClick);
}
@凌驾
公共空间{
super.ondestory();
helper.close();
}
private View.OnClickListener onSave=new View.OnClickListener(){
公共void onClick(视图v){
字符串类型=null;
开关(type.getCheckedRadioButtonId()){
案例R.id.坐下:
type=“坐下”;
打破
案例R.id.取出:
type=“取出”;
打破
案例R.id.交付:
type=“交付”;
打破
}
helper.insert(name.getText().toString(),
address.getText().toString(),类型,
notes.getText().toString());
model.requery();
}
};
private AdapterView.OnItemClickListener onListClick=new AdapterView.OnItemClickListener(){
公共无效MClick(AdapterView父级、,
视图,int位置,
长id){
模型。移动位置(位置);
name.setText(helper.getName(model));
address.setText(helper.getAddress(model));
setText(helper.getNotes(model));
if(helper.getType(model.equals(“坐下”)){
类型。检查(R.id.坐下);
}
else if(helper.getType(model).equals(“take_out”)){
类型。检查(R.id.取出);
}
否则{
类型。检查(R.id.交付);
}
getTabHost().setCurrentTab(1);
}
};
类restaurantapter扩展了CursorAdapter{
Restaurantapter(光标c){
超级(午餐清单,本,c);
}
@凌驾
public void bindView(视图行、上下文ctxt、,
光标(c){
RestaurantHolder=(RestaurantHolder)行。getTag();
持有者。从(c,助手)开始普及;
}
@凌驾
公共视图新建视图(上下文ctxt,光标c,
视图组(父级){
LayoutInflater充气机=getLayoutInflater();
视图行=充气机。充气(R.layout.row,父级,false);
餐厅持有人=新餐厅持有人(世界其他地区);
row.setTag(支架);
返回(行);
}
}
静态类RestaurantHolder{
私有文本视图名称=null;
私有文本视图地址=空;
私有ImageView图标=空;
RestaurantHolder(视图行){
name=(TextView)row.findViewById(R.id.title);
address=(TextView)row.findViewById(R.id.address);
icon=(ImageView)row.findViewById(R.id.icon);
}
无效populateFrom(光标c,RestaurantHelper助手){
name.setText(helper.getName(c));
address.setText(helper.getAddress(c));
if(helper.getType(c).equals(“坐下”)){
图标.setImageResource(R.drawable.ball_红色);
}
else if(helper.getType(c).equals(“take_out”)){
图标.setImageResource(R.drawable.ball_黄色);
}
否则{
图标.setImageResource(R.drawable.ball_绿色);
}
}
}
}
将新按钮(btnDelete)添加到布局xml中
使用Button btnDel=(Button)findviewbyd(R.id.btnDelete)将其装载到代码中代码>
使用:
btnDel.setOnClickListener)new OnClickListener()
{
@Override
public void onClick(View v)
{
//add SQL deletion code here
}
});
最后在onClickListener中执行SQL删除语句;) 我相当肯定您需要继续学习教程。看过Commons_Ware(这本书的作者和这里非常活跃的成员)的网站后,我怀疑他会让你绞死。我确信他一步一步地教授完整的CRUD模型
顺便说一句,如果你还没有订阅他的书,我强烈推荐。它们经常更新以包含最新信息。如果您可以检查匹配的ID,这可能会起作用
db.execSQL("DELETE FROM restaurants WHERE id = '+" idToDelete "+' ;");
不要使用execSQL()
进行删除,而是使用以下命令:
要删除整个表,请执行以下操作:
db.delete(DATABASE_TABLE, null, null);
要删除表中的特定记录,请执行以下操作:
db.delete(DATABASE_TABLE, whereCondition, null);
例如:
db.de