Take a look at the following code, I use the first code, remote database data can be read, but when using the second code will not be able to read a remote database code, only print out the "query" success, don't seem to be performed, the following code (using the studio software - kotlin)

This is the first piece of code and execution result in the following:

 
The import kotlin. Concurrent. Thread 

Fun main () {
ZhusuInOut1 () 

} 
Private fun zhusuInOut1 () {
Val queryInList1=ArrayList () 
Try {
Thread {
Val conn=DBUtil (.) conection () 
Try {
Val sql1="SELECT * FROM zhusuintable where name='75 g and color=' no '" 
//create objects needed to execute SQL statements 
//val statement: statement=conn!!!!! CreateStatement () 
Val preparedStatement=conn!!!!! . PrepareStatement (sql1) 
//execute SQL query and retrieve the query information 
//val rSet1: the ResultSet=statement. The executeQuery (sql1) 
Val resultSet=preparedStatement. ExecuteQuery () 
Println (" query ") 
While (resultSet. Next ()) {
Shuliang val tile1=the resultSet. Get string (" ") 
QueryInList1. Add (tile1) 
Println (" query data to set successful ") 
For (I in queryInList1) {
Println (I) 
} 
} 
{} the catch (e: Exception) 
E.p rintStackTrace () 
} 
} 
{} the catch (e: Exception) 
E.p rintStackTrace () 
} 

} 

The first piece of code execution result is as follows:

 
Query success 
Join query data collection success 
5622 
Join query data collection success 
5622 
2314 

This is the second piece of code and execution result below:

 
The import android. OS. Bundle 
The import android. Util. Log 
The import kotlinx. Android. Synthetic. Main. Query_in_out_layout. * 
The import kotlinx. Android. Synthetic. Main. Super_manager_layout. The toolbar 
Import the Java. SQL. The ResultSet 
Import the Java. SQL. SQLException 
Import of Java, SQL Statement 
The import kotlin. Concurrent. Thread 

The class TestInOut: BaseActivity () {
Override fun onCreate (savedInstanceState: Bundle? {
Super. OnCreate (savedInstanceState) 
The setContentView (R.l ayout. Test_in_out) 
SetSupportActionBar (toolbar) 

Thread {
TestQueryBtm. SetOnClickListener {
Try {
Thread {
Val conn=DBUtil (.) conection () 
Try {
Val queryInList1=ArrayList () 
Val sql1="SELECT * FROM zhusuintable where name='75 g and color=' no '" 
//create objects needed to execute SQL statements 
Val statement: statement=conn!!!!! CreateStatement () 
//val preparedStatement=conn!!!!! . PrepareStatement (sql1) 
//execute SQL query and retrieve the query information 
Val rSet1: the ResultSet=statement. ExecuteQuery (sql1) 
//val resultSet=preparedStatement. ExecuteQuery () 
Println (" query ") 
While (rSet1. Next ()) {
Shuliang val find1=rSet1. Get string (" ") 
QueryInList1. Add (find1) 
Println (" query data to set successful ") 
} 
{} the catch (e: Exception) 
E.p rintStackTrace () 
} 
Try {
Conn!!!!! The close () 
The d (" QueryInOut ", "close the database connection is successful,") 
{} the catch (e: SQLException) 
The d (" QueryInOut ", "close the connection fails,") 
} 
} 
{} the catch (e: Exception) 
E.p rintStackTrace () 
} 
} 
} 

} 
Private fun test11 () {

} 
} 

If the above code execution is as follows:

 
D/BaseActivity: TestInOut 
I/System. Out: query success 
D/QueryInOut: close the database connection is successful,