Missing every swing element in java in netbeans, project correpted - user-interface

Question

I don't know why this class shows errors in every line. This was fine but suddenly i close and open my netbeans IDE and it shows every-line error.
I tried to figure out where the problem is, but i can't. I notice that every button,table,label are missing, otherwise variable, database connection is ok.
My imports are:
import javax.swing.*;
import java.awt.*;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import Main.SqlConnection;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;
import net.proteanit.sql.DbUtils;
import Main.Check;
import java.awt.Color;
import java.awt.event.KeyEvent;
Errors look like this image .
How do i solve this ?
Do i need to recover my project ?

Answer 1

add try{ block just before following line
private void btn_SaveActionPerformed(java.awt.event.ActionEvent evt) {

Answer 2

Your solution as follows
Consider following method. It don't contain a try keyword. add try keyword there. Then it will be fixed.
private void btn_SaveActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
try { //this line is not present in your code. add this
StringBuffer stringBuffer = new StringBuffer();
if (value_for_show_table == 61) {
stringBuffer.append("insert into class6a where ");
} else if (value_for_show_table == 62) {
stringBuffer.append("insert into class6b where ");
} else if (value_for_show_table == 71) {
stringBuffer.append("insert into class7a where ");
} else if (value_for_show_table == 72) {
stringBuffer.append("insert into class7b where ");
} else if (value_for_show_table == 81) {
stringBuffer.append("insert into class8a where ");
} else if (value_for_show_table == 82) {
stringBuffer.append("insert into class8b ");
}
stringBuffer.append("where '" + txt_Username.getText() + "','" + txt_roll.getText() + "','" + txt_Bangla1st.getText() + "',"
+ "'" + txt_Bangla2nd.getText() + "','" + txt_English1st.getText() + "','" + txt_English2nd.getText() + "',"
+ "'" + txt_Math.getText() + "','" + txt_Social.getText() + "','" + txt_Religion.getText() + "',");
} catch (Exception e) {
JOptionPane.showMessageDialog(null, "Roll number can't be duplicate");
}
}
Additionally It may happen according to many reasons. There are one of them.
When project cannot find the JDK location or when missing core library of java
When using a reserved word as a parameter or class name