i have made simple science quiz java app 4 frames: login, menu, test, , result.
the first 3 frames working fine when click on show result shows error. code result jframe. if want can send coding of test jframe also.
this error
java.sql.sqlexception: illegal operation on empty result set. @ com.mysql.jdbc.sqlerror.createsqlexception(sqlerror.java:1055) @ com.mysql.jdbc.sqlerror.createsqlexception(sqlerror.java:956) @ com.mysql.jdbc.sqlerror.createsqlexception(sqlerror.java:926) @ com.mysql.jdbc.resultsetimpl.checkrowpos(resultsetimpl.java:815) @ com.mysql.jdbc.resultsetimpl.getstringinternal(resultsetimpl.java:5528) @ com.mysql.jdbc.resultsetimpl.getstring(resultsetimpl.java:5448) @ com.mysql.jdbc.resultsetimpl.getfloat(resultsetimpl.java:2499) @ test.resultbtnactionperformed(test.java:292) @ test.access$500(test.java:18) @ test$6.actionperformed(test.java:215) @ javax.swing.abstractbutton.fireactionperformed(abstractbutton.java:1995) @ javax.swing.abstractbutton$handler.actionperformed(abstractbutton.java:2318) @ javax.swing.defaultbuttonmodel.fireactionperformed(defaultbuttonmodel.java:387) @ javax.swing.defaultbuttonmodel.setpressed(defaultbuttonmodel.java:242) @ javax.swing.plaf.basic.basicbuttonlistener.mousereleased(basicbuttonlistener.java:236) @ java.awt.component.processmouseevent(component.java:6216) @ javax.swing.jcomponent.processmouseevent(jcomponent.java:3265) @ java.awt.component.processevent(component.java:5981) @ java.awt.container.processevent(container.java:2041) @ java.awt.component.dispatcheventimpl(component.java:4583) @ java.awt.container.dispatcheventimpl(container.java:2099) @ java.awt.component.dispatchevent(component.java:4413) @ java.awt.lightweightdispatcher.retargetmouseevent(container.java:4556) @ java.awt.lightweightdispatcher.processmouseevent(container.java:4220) @ java.awt.lightweightdispatcher.dispatchevent(container.java:4150) @ java.awt.container.dispatcheventimpl(container.java:2085) @ java.awt.window.dispatcheventimpl(window.java:2475) @ java.awt.component.dispatchevent(component.java:4413) @ java.awt.eventqueue.dispatchevent(eventqueue.java:599) @ java.awt.eventdispatchthread.pumponeeventforfilters(eventdispatchthread.java:269) @ java.awt.eventdispatchthread.pumpeventsforfilter(eventdispatchthread.java:184) @ java.awt.eventdispatchthread.pumpeventsforhierarchy(eventdispatchthread.java:174) @ java.awt.eventdispatchthread.pumpevents(eventdispatchthread.java:169) @ java.awt.eventdispatchthread.pumpevents(eventdispatchthread.java:161) @ java.awt.eventdispatchthread.run(eventdispatchthread.java:122)
import java.sql.*; import javax.swing.table.*; import javax.swing.joptionpane; public class result extends javax.swing.jframe { float result; string id; /** creates new form result */ public result() { initcomponents(); } public result(float res, string id) { initcomponents(); result = res; id = id; score.settext(res + "%"); try { class.forname("java.sql.driver"); string database = "jdbc:mysql://localhost:3306/quizdb"; connection conn = drivermanager.getconnection(database, "root", "1234"); statement stmt = conn.createstatement(); string sql = "select * result id = '" + id + "'"; resultset rs = stmt.executequery(sql); object[] newrow = new object[5]; newrow[0] = "max marks"; rs.next(); for(int i=1; i<=4;i++) newrow = rs.getstring(i+1); defaulttablemodel tm = (defaulttablemodel)scoretbl.getmodel(); tm.addrow(newrow); } catch (exception e) { joptionpane.showmessagedialog(null,"" + e); } } coding of testjframe
import java.sql.*; import javax.swing.joptionpane; public class test extends javax.swing.jframe { string id; string subject; int index =1; int max =0; int result = 0; char [] answers; /** creates new form test */ public test() { initcomponents(); } public test(string subject, string id) { initcomponents(); id = id; subject = subject; prevbtn.setvisible(false); try { class.forname("java.sql.driver"); string database = "jdbc:mysql://localhost:3306/quizdb"; connection conn = drivermanager.getconnection(database, "root", "1234"); statement stmt = conn.createstatement(); string sql = "select max(sno) " + subject; resultset rs = stmt.executequery(sql); rs.next(); max = rs.getint(1); answers = new char[max]; for(int i=0; i<max;i++) answers[i] = 'e'; rs.close(); stmt.close(); conn.close(); getques(); } catch(exception e){ joptionpane.showmessagedialog(null,""+ e); } } private void getques() { try { /* class.forname("sun.jdbc.odbc.jdbcodbcdriver"); string database ="jdbc:odbc:driver={microsoft access driver (*.mdb)};dbq=elearning.mdb;"; connection conn = drivermanager.getconnection(database, "", ""); statement stmt = conn.createstatement(); */ class.forname("java.sql.driver"); string database = "jdbc:mysql://localhost:3306/quizdb"; connection conn = drivermanager.getconnection(database, "root", "1234"); statement stmt = conn.createstatement(); string sql = "select * " + subject + " sno = " + index; resultset rs = stmt.executequery(sql); rs.next(); questa.settext("\nq" + index + ". " + rs.getstring(2)); a.settext(rs.getstring("a")); b.settext(rs.getstring("b")); c.settext(rs.getstring("c")); d.settext(rs.getstring("d")); a.setselected(answers[index-1] == 'a'); b.setselected(answers[index-1] == 'b'); c.setselected(answers[index-1] == 'c'); d.setselected(answers[index-1] == 'd'); e.setselected(answers[index-1] == 'e'); rs.close(); stmt.close(); conn.close(); } catch(exception e){ joptionpane.showmessagedialog(null,""+ e); } } private void prevbtnactionperformed(java.awt.event.actionevent evt) { index--; getques(); if(index == 1) prevbtn.setvisible(false); if(index < max) nextbtn.setvisible(true); } private void nextbtnactionperformed(java.awt.event.actionevent evt) { index++; getques(); if(index == max) nextbtn.setvisible(false); if(index > 1) prevbtn.setvisible(true); } private void bactionperformed(java.awt.event.actionevent evt) { answers[index-1] = 'b'; } private void resultbtnactionperformed(java.awt.event.actionevent evt) { try { /* class.forname("sun.jdbc.odbc.jdbcodbcdriver"); string database ="jdbc:odbc:driver={microsoft access driver (*.mdb)};dbq=elearning.mdb;"; connection conn = drivermanager.getconnection(database, "", ""); statement stmt = conn.createstatement(); */ class.forname("java.sql.driver"); string database = "jdbc:mysql://localhost:3306/quizdb"; connection conn = drivermanager.getconnection(database, "root", "1234"); statement stmt = conn.createstatement(); string sql = "select result " + subject; resultset rs = stmt.executequery(sql); int = 0; while(rs.next()) { char ans = rs.getstring(1).charat(0); if(ans == answers[i]) result++; i++; } float res = ((float)result * 100 ) / max; sql = "select " + subject + "result result id = '" + id + "'"; rs = stmt.executequery(sql); rs.next(); if(res > rs.getfloat(1)) { sql = "update result set " + subject + "result = " + res + " id = '" + id + "'"; stmt.executeupdate(sql); } stmt.close(); conn.close(); new result(res,id).setvisible(true); this.setvisible(false); } catch(exception e){ joptionpane.showmessagedialog(null,""+ e); } } private void aactionperformed(java.awt.event.actionevent evt) { answers[index-1] = 'a'; } private void cactionperformed(java.awt.event.actionevent evt) { answers[index-1] = 'c'; } private void dactionperformed(java.awt.event.actionevent evt) { answers[index-1] = 'd'; } /** * @param args command line arguments */ public static void main(string args[]) { java.awt.eventqueue.invokelater(new runnable() { public void run() { new test().setvisible(true); } }); }
change code
rs.next(); for(int i=1; i<=4;i++) newrow = rs.getstring(i+1); defaulttablemodel tm = (defaulttablemodel)scoretbl.getmodel(); tm.addrow(newrow); to
defaulttablemodel tm = (defaulttablemodel)scoretbl.getmodel(); while(rs.next()) { java.util.vector row = new java.util.vector(); for(int i=1; i<=4;i++) { row.add(rs.getstring(i)); } tm.addrow(row); } edit:
in code written this
rs.next(); max = rs.getint(1); change
if(rs.next()) max = rs.getint(1); if above condition true next statement evaluated.
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