我是一枚新手,在写添加listview并对数据库进行增删改查时遇到了问题,添加listview时我想添加一个item可是一添加就添加了好多行,还有插入数据后不能listview没有显示之前插入的值,求大神给看看!这是我的代码:
public class DLXMainActivity extends AppCompatActivity {
private Toolbar mToolbar;
public static EditText mDlxInput1, mDlxInput2;//输入框
public TextView mTitle, mContent, mTime;//显示内容
DatabaseHelper mDatabaseHelper = new DatabaseHelper(this);
static List<Comment> mList = new ArrayList<>();
static Comment mComment = new Comment();
MyAdapter mAdapter;
ListView mListView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dlx_task3_dlxmain);
initViewValue();
}
public void initViewValue() {
findViews();
setSupportActionBar(mToolbar);
setOnclicklistener();
}
//数据库的初始化和按下删除的监听事件
public void setOnclicklistener() {
mDatabaseHelper = new DatabaseHelper(this);
mAdapter = new MyAdapter(this, mList);
mListView.setAdapter(mAdapter);
mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
mComment = mList.get(position);
int positioncurrent = mComment.getId();
mDatabaseHelper.databaseDelete(positioncurrent);
mList.remove(mComment);
mAdapter.notifyDataSetChanged();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.dlx_task3_menu, menu);
return super.onCreateOptionsMenu(menu);
}
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_add:
showDialog_Layout(DLXMainActivity.this);
break;
}
return super.onOptionsItemSelected(item);
}
//对话框
private void showDialog_Layout(final Context context) {
LayoutInflater inflater = LayoutInflater.from(this);
final View textEntryView = inflater.inflate(R.layout.dlx_task3_dialoglayout, null);
final AlertDialog.Builder builder = new AlertDialog.Builder(context);
mDlxInput1 = (EditText) textEntryView.findViewById(R.id.dlx_Input1);
mDlxInput2 = (EditText) textEntryView.findViewById(R.id.dlx_Input2);
builder.setCancelable(false);
builder.setTitle(R.string.dlx_add);
builder.setView(textEntryView);
builder.setNegativeButton(android.R.string.cancel,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
setTitle("");
}
});
builder.setPositiveButton(android.R.string.ok,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
mDatabaseHelper.databaseInsert();
mDatabaseHelper.databaseFind(context);
mAdapter.notifyDataSetChanged();
}
});
builder.show();
}
public void findViews() {
mToolbar = (Toolbar) findViewById(R.id.toolbar);
mTitle = (TextView) findViewById(R.id.dlx_maintitle);
mContent = (TextView) findViewById(R.id.dlx_maincontent);
mTime = (TextView) findViewById(R.id.dlx_maintime);
mListView = (ListView) findViewById(R.id.dlx_lv);
}
}
public class MyAdapter extends BaseAdapter {
public List<Comment> list;
public LayoutInflater mInflater = null;
Context context;
DatabaseHelper mDatabaseHelper = new DatabaseHelper(context);
public MyAdapter(Context context, List<Comment> list) {
this.mInflater = LayoutInflater.from(context);
this.context = context;
this.list = list;
}
//ViewHolder静态类
static class ViewHolder {
public TextView title;
public TextView content;
public TextView time;
}
@Override
public int getCount() {
return list.size();
}
@Override
public Object getItem(int position) {
return list.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
//获取一个在数据集中指定索引的视图来显示数据
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
//如果缓存convertView为空,则需要创建View
if (convertView == null) {
holder = new ViewHolder();
//根据自定义的Item布局加载布局
convertView = mInflater.inflate(R.layout.dlx_task3_commentlayout, null);
holder.title = (TextView) convertView.findViewById(R.id.dlx_maintitle);
holder.content = (TextView) convertView.findViewById(R.id.dlx_maincontent);
holder.time = (TextView) convertView.findViewById(R.id.dlx_maintime);
//将设置好的布局保存到缓存中,并将其设置在Tag里,以便后面方便取出Tag
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.title.setText(list.get(position).getTitle());
holder.content.setText(list.get(position).getContent());
holder.time.setText(mDatabaseHelper.getTimeShow(context, (list.get(position).getTime())));
return convertView;
}
}
public class DatabaseHelper extends SQLiteOpenHelper {
public static final int DATABASE_VERSION = 1;
public static final String DATABASE_NAME = "Comment.db";
public static final String TABLE_NAME = " comment";
public long mDatetimecurrent;
Context context;
public long mDatetime;
// TODO: 2016/5/18
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE" + TABLE_NAME + "(" +
Comment.Commentinter.EVENT_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
Comment.Commentinter.EVENT_TITLE + " TEXT NOT NULL, " +
Comment.Commentinter.EVENT_CONTENT + " TEXT NOT NULL, " +
Comment.Commentinter.EVENT_TIME + " INTEGER NOT NULL);");
}
public void databaseInsert() {
SQLiteDatabase db = getWritableDatabase();
ContentValues values = new ContentValues();
mDatetime = System.currentTimeMillis();
//开始组装第一条数据
values.put("title", String.valueOf(DLXMainActivity.mDlxInput1.getText()));
values.put("content", String.valueOf(DLXMainActivity.mDlxInput2.getText()));
values.put("time", mDatetime);
db.insert(TABLE_NAME, null, values);//插入第一条数据
db.close();
}
/**
* 删除数据库元素
*
* @param
*/
public void databaseDelete(int positioncurrent) {
SQLiteDatabase db = getWritableDatabase();
String[] args = {String.valueOf(positioncurrent)};
db.delete("comment", Comment.Commentinter.EVENT_ID + "=?", args);
db.close();
}
/**
* 从数据库中取值并放到listview中
* @param context
*/
public void databaseFind(Context context) {
this.context = context;
SQLiteDatabase db = getReadableDatabase();
Cursor cursor = db.query(DatabaseHelper.TABLE_NAME,new String[]
{Comment.Commentinter.EVENT_ID, Comment.Commentinter.EVENT_TITLE,
Comment.Commentinter.EVENT_CONTENT,Comment.Commentinter.EVENT_TIME},
null, null, null, null, null, null);
//DLXMainActivity.mList.clear();
while (cursor.moveToNext()) {
String title = cursor.getString(cursor.getColumnIndex(Comment.Commentinter.EVENT_TITLE));
String content = cursor.getString(cursor.getColumnIndex(Comment.Commentinter.EVENT_CONTENT));
long time = cursor.getLong(cursor.getColumnIndex(Comment.Commentinter.EVENT_TIME));
int id = cursor.getInt(cursor.getColumnIndex(Comment.Commentinter.EVENT_ID));
DLXMainActivity.mComment.setTitle(title);
DLXMainActivity.mComment.setContent(content);
DLXMainActivity.mComment.setTime(time);
DLXMainActivity.mComment.setId(id);
DLXMainActivity.mList.add(DLXMainActivity.mComment);
}
cursor.close();
db.close();
}
public String getTimeShow(Context context, long datetime) {
mDatetimecurrent = System.currentTimeMillis();
long time = mDatetimecurrent - datetime;
if (time / 1000 != 0) {
if (time / 60000 != 0) {
if (time / 3600000 != 0) {
if (time / 86400000 != 0) {
return time / 86400000 + context.getString(R.string.dlx_day1);
} else {
return time / 3600000 + context.getString(R.string.dlx_hour);
}
} else {
return time / 60000 + context.getString(R.string.dlx_minute);
}
} else {
return time / 1000 + context.getString(R.string.dlx_second);
}
} else {
return context.getString(R.string.dlx_gang);
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
onCreate(db);
}
@Override
public void onOpen(SQLiteDatabase db) {
super.onOpen(db);
}