Java Android studio sqlite到listview
论创作方法Java Android studio sqlite到listview,java,android,sqlite,listview,android-sqlite,Java,Android,Sqlite,Listview,Android Sqlite,论创作方法 db = openOrCreateDatabase("messages", MODE_PRIVATE, null); db.execSQL("CREATE TABLE IF NOT EXISTS message(msg TEXT);"); db.execSQL("INSERT INTO message values('example');"); listeview1 = (ListView) findViewById(R.id.listview
db = openOrCreateDatabase("messages", MODE_PRIVATE, null);
db.execSQL("CREATE TABLE IF NOT EXISTS message(msg TEXT);");
db.execSQL("INSERT INTO message values('example');");
listeview1 = (ListView) findViewById(R.id.listview);
ArrayList<String> dbArray = myArrayListTodatabase();
ListAdapter mylistadapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, dbArray);
listview.setAdapter(mylistadapter);
db=openOrCreateDatabase(“messages”,MODE_PRIVATE,null);
execSQL(“如果不存在,则创建表消息(消息文本);”;
execSQL(“插入到消息值('example');”;
ListView1=(ListView)findViewById(R.id.ListView);
ArrayList dbArray=myArrayListTodatabase();
ListAdapter mylistadapter=new ArrayAdapter(这是android.R.layout.simple_list_item_1,dbArray);
setAdapter(mylistadapter);
Myarraylisttodatabase代码
public ArrayList<String> myArrayListTodatabase() {
db = openOrCreateDatabase("messages", MODE_PRIVATE, null);
db.rawQuery("Select * from message", null);
Cursor c = db.rawQuery("Select * from message", null);
c.moveToFirst();
String dbString = "";
while (!c.isAfterLast()) {
if (c.getString(c.getColumnIndex("msg")) != null) {
dbString += c.getString(c.getColumnIndex("msg"));
dbString += "\n";
}
c.moveToNext();
}
db.close();
return myArraylist;
}
public ArrayList myArrayListTodatabase(){
db=openOrCreateDatabase(“消息”,模式_PRIVATE,null);
db.rawQuery(“从消息中选择*”,空);
游标c=db.rawQuery(“从消息中选择*项”,null);
c、 moveToFirst();
字符串dbString=“”;
而(!c.isAfterLast()){
if(c.getString(c.getColumnIndex(“msg”)!=null){
dbString+=c.getString(c.getColumnIndex(“msg”);
dbString+=“\n”;
}
c、 moveToNext();
}
db.close();
返回myArraylist;
}
全局变量
SQLiteDatabase db = null;
public ArrayList<String> myArraylist = new ArrayList<String>();
SQLiteDatabase db=null;
public ArrayList myArraylist=新建ArrayList();
我正在使用这些工具,但是当我运行应用程序时,listview中没有输出。你根本没有向ArrayList添加内容。添加
myArraylist。添加(dbString)
或填充ArrayList以供ListView使用的内容。您根本没有向ArrayList添加内容。添加myArraylist。添加(dbString)
或填充ArrayList以供ListView使用的内容。您忘记插入ArrayList。使用以下函数更新您的函数:
public ArrayList<String> myArrayListTodatabase() {
myArraylist.clear();
db = openOrCreateDatabase("messages", MODE_PRIVATE, null);
db.rawQuery("Select * from message", null);
Cursor c = db.rawQuery("Select * from message", null);
String dbString = "";
while (c.moveToNext()) {
if (!c.getString(c.getColumnIndex("msg")).equals("")) {
myArraylist.add(c.getString(c.getColumnIndex("msg")));
}
}
c.close();
db.close();
return myArraylist;
}
public ArrayList myArrayListTodatabase(){
myArraylist.clear();
db=openOrCreateDatabase(“消息”,模式_PRIVATE,null);
db.rawQuery(“从消息中选择*”,空);
游标c=db.rawQuery(“从消息中选择*项”,null);
字符串dbString=“”;
while(c.moveToNext()){
如果(!c.getString(c.getColumnIndex(“msg”))。等于(“”){
添加(c.getString(c.getColumnIndex(“msg”));
}
}
c、 close();
db.close();
返回myArraylist;
}
您忘记插入ArrayList。使用以下函数更新您的函数:
public ArrayList<String> myArrayListTodatabase() {
myArraylist.clear();
db = openOrCreateDatabase("messages", MODE_PRIVATE, null);
db.rawQuery("Select * from message", null);
Cursor c = db.rawQuery("Select * from message", null);
String dbString = "";
while (c.moveToNext()) {
if (!c.getString(c.getColumnIndex("msg")).equals("")) {
myArraylist.add(c.getString(c.getColumnIndex("msg")));
}
}
c.close();
db.close();
return myArraylist;
}
public ArrayList myArrayListTodatabase(){
myArraylist.clear();
db=openOrCreateDatabase(“消息”,模式_PRIVATE,null);
db.rawQuery(“从消息中选择*”,空);
游标c=db.rawQuery(“从消息中选择*项”,null);
字符串dbString=“”;
while(c.moveToNext()){
如果(!c.getString(c.getColumnIndex(“msg”))。等于(“”){
添加(c.getString(c.getColumnIndex(“msg”));
}
}
c、 close();
db.close();
返回myArraylist;
}