【发布时间】：2019-02-01 00:24:17
【问题描述】：
大家好，我是 android SQLiteDatabase 的新手。我正在关注本网站 ORIGINAL CODE 的教程。下面的代码是关于从数据库中添加、更新、删除名称的。
一切正常。我能够在数据库中添加、更新和删除名称。
问题： 例如我添加了 4 个名字。
ID name
1 A
2 B
3 C
4 D
当我删除 A 时，它会从列表视图和数据库中删除。它在列表视图中更新。 现在数据库是这样的
ID name
1 null
2 B
3 C
4 D
Listview 是这样的
B
C
D
因此，当我单击 B 进行删除或编辑时，它在我的编辑和删除视图中没有显示任何内容，但是当我单击 C 时，它在删除视图中显示 B。
我浏览了 stackoverflow 中提供的所有解决方案，我知道这是重复的问题，但是对于这个例子有什么解决方案。 我希望当我点击 B 时它应该显示 B 不为空，当我点击 C 时它应该显示 C，删除 A 后。
注意：请任何人修复代码。我很确定有许多开发人员正在寻找解决此问题的方法。特别是像我这样的初学者。这将是很大的帮助。在此先感谢您。
DBHelper
public Integer deleteContact (Integer id) {
SQLiteDatabase db = this.getWritableDatabase();
return db.delete("contacts",
"id = ? ",
new String[] { Integer.toString(id) });
}
public ArrayList<String> getAllCotacts() {
ArrayList<String> array_list = new ArrayList<String>();
//hp = new HashMap();
SQLiteDatabase db = this.getReadableDatabase();
Cursor res = db.rawQuery( "select * from contacts", null );
res.moveToFirst();
while(res.isAfterLast() == false){
array_list.add(res.getString(res.getColumnIndex(CONTACTS_COLUMN_NAME)));
res.moveToNext();
}
return array_list;
}
devicedetailsActivity
public class devicedetailsActivity extends AppCompatActivity {
public final static String EXTRA_MESSAGE = "MESSAGE";
private ListView obj;
DBHelper mydb;
ArrayList array_list ;
public ArrayAdapter arrayAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.devicedetails_layout);
mydb = new DBHelper(this);
}
public void onResume() {
refreshList();
super.onResume();
}
public void refreshList() {
array_list = mydb.getAllCotacts();
arrayAdapter=new ArrayAdapter(this,R.layout.simple_list_item_1, array_list);
obj = (ListView)findViewById(R.id.listView1);
obj.setAdapter(arrayAdapter);
obj.setOnItemClickListener(new AdapterView.OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {
// TODO Auto-generated method stub
int id_To_Search = arg2 + 1;
Bundle dataBundle = new Bundle();
dataBundle.putInt("id", id_To_Search);
Intent intent = new Intent(getApplicationContext(),DetailsActivity.class);
intent.putExtras(dataBundle);
startActivity(intent);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
getMenuInflater().inflate(R.menu.home, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item){
super.onOptionsItemSelected(item);
switch(item.getItemId()) {
case R.id.item1:Bundle dataBundle = new Bundle();
dataBundle.putInt("id", 0);
Intent intent = new Intent(getApplicationContext(),DetailsActivity.class);
intent.putExtras(dataBundle);
startActivity(intent);
return true;
case R.id.item2: dataBundle = new Bundle();
dataBundle.putInt("id", 0);
intent = new Intent(getApplicationContext(),MainActivity.class);
intent.putExtras(dataBundle);
startActivity(intent);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
DetailsActivity
public class DetailsActivity extends AppCompatActivity {
private DBHelper mydb ;
ArrayAdapter arrayAdapter;
TextView name ;
int id_To_Update = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.details);
name = (TextView) findViewById(R.id.editTextName);
mydb = new DBHelper(this);
Bundle extras = getIntent().getExtras();
if(extras !=null) {
int Value = extras.getInt("id");
if(Value>0){
//means this is the view part not the add contact part.
Cursor rs = mydb.getData(Value);
if(rs.moveToFirst()) {
id_To_Update = Value;
rs.moveToFirst();
String nam = rs.getString(rs.getColumnIndex(DBHelper.CONTACTS_COLUMN_NAME));
Button b = (Button)findViewById(R.id.button1);
b.setVisibility(View.INVISIBLE);
name.setText((CharSequence)nam);
name.setFocusable(false);
name.setClickable(false);
}
if (!rs.isClosed()) {
rs.close();
}
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
Bundle extras = getIntent().getExtras();
if(extras !=null) {
int Value = extras.getInt("id");
if(Value>0){
getMenuInflater().inflate(R.menu.display_contact, menu);
} else{
getMenuInflater().inflate(R.menu.back, menu);
}
}
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
super.onOptionsItemSelected(item);
switch(item.getItemId()) {
case R.id.Edit_Contact:
Button b = (Button)findViewById(R.id.button1);
b.setVisibility(View.VISIBLE);
name.setEnabled(true);
name.setFocusableInTouchMode(true);
name.setClickable(true);
return true;
case R.id.Delete_Contact:
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage(R.string.deleteContact)
.setPositiveButton(R.string.yes, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
mydb.deleteContact(id_To_Update);
Toast.makeText(getApplicationContext(), "Deleted Successfully",
Toast.LENGTH_SHORT).show();
Intent intent = new Intent(getApplicationContext(),devicedetailsActivity.class);
startActivity(intent);
}
})
.setNegativeButton(R.string.no, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// User cancelled the dialog
}
});
AlertDialog d = builder.create();
d.setTitle("Are you sure");
d.show();
return true;
case R.id.back:
Intent intent = new Intent(getApplicationContext(),devicedetailsActivity.class);
startActivity(intent);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
public void run(View view) {
Bundle extras = getIntent().getExtras();
if(extras !=null) {
int Value = extras.getInt("id");
if(Value>0){
if(mydb.updateContact(id_To_Update,name.getText().toString()
)){
Toast.makeText(getApplicationContext(), "Updated", Toast.LENGTH_SHORT).show();
Intent intent = new Intent(getApplicationContext(),devicedetailsActivity.class);
startActivity(intent);
} else{
Toast.makeText(getApplicationContext(), "not Updated", Toast.LENGTH_SHORT).show();
}
} else{
if(mydb.insertContact(name.getText().toString())){
Toast.makeText(getApplicationContext(), "done",
Toast.LENGTH_SHORT).show();
} else{
Toast.makeText(getApplicationContext(), "not done",
Toast.LENGTH_SHORT).show();
}
Intent intent = new Intent(getApplicationContext(),devicedetailsActivity.class);
startActivity(intent);
}
}
}
}
【问题讨论】：
-
不要使用
ArrayAdapter，而是使用SimpleCursorAdapter- 请仔细阅读下面MikeT的优秀答案
标签： java android database sqlite listview