Modify

     int Admission_Number= Integer.parseInt(jTextField1.getText());
        try{
        Class.forName("java.sql.DriverManager");
        Connection con=(Connection)
        DriverManager.getConnection("jdbc:mysql://localhost:3306/STUDENT","root","tiger");
        Statement stmt=(Statement) con.createStatement();
        String query="SELECT Student_Name, Stream FROM STUDENT WHERE Admission_Number=’”+Admission_Number+”’;";
        ResultSet rs= stmt.executeQuery(query);

        if(rs.next())
        {
          String STUDENT_NAME= rs.getString("STUDENT_NAME");
          String STREAM= rs.getString("STREAM");
          jTextField2.setText(STUDENT_NAME);
          jTextField3.setText(STREAM);
        }
        }
        catch(Exception e){
                JOptionPane.showMessageDialog(this, e.getMessage());
    }