Android app crashes when clicking on an item in the list view

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My app does the following:

-Enter name of employee, click search button.

-List of matching names as a result.

-When click one of the resulted names.

Edited

The stack-trace that has been added to the question has a line that says

java.lang.IllegalStateException: Cannot perform this operation because the connection pool has been closed.

This is saying that the connection(s as there may be a number, hence the connection pool) has been closed. The connection being the connection(s) to the database. It is closed because you have specifically closed it using EmpDept.close().

When a Cursor is created, it doesn't actually contain the data, rather it reads the data from the database when that data is needed. If the database has been closed then it cannot get the data.

e.g. you have :-

        cur.moveToFirst();
        EmpDept.close(); //<<<<<<<<<< Database connection closed
        return cur;

In short you cannot close the database connection and then access data in the Cursor.

Here's a complete working solution that doesn't include the above flaw nor other flaws (some indicated by comments).

First a new Class named Employee in Employee.java

public class Employee {

    private long employeeId;
    private String employeeName;
    private String employeeTitle;
    private String employeePhone;
    private String employeeEmail;
    private long employeeDeptId;
    private String employeeDeptName;

    public Employee(
            long id,
            String name,
            String title,
            String phone,
            String email,
            long deptid,
            String deptname
    ) {
        this.employeeId = id;
        this.employeeName = name;
        this.employeeTitle = title;
        this.employeePhone = phone;
        this.employeeEmail = email;
        this.employeeDeptId = deptid;
        this.employeeDeptName = deptname;
    }

    public Employee() {
        this(-1L,"","","","",-1L,"");
    }

    public Employee(String name, String title, String phone, String email) {
        this(-1L,name,title,phone,email,-1L,"");
    }

    public long getEmployeeId() {
        return employeeId;
    }

    public void setEmployeeId(long employeeId) {
        this.employeeId = employeeId;
    }

    public String getEmployeeName() {
        return employeeName;
    }

    public void setEmployeeName(String employeeName) {
        this.employeeName = employeeName;
    }

    public String getEmployeeTitle() {
        return employeeTitle;
    }

    public void setEmployeeTitle(String employeeTitle) {
        this.employeeTitle = employeeTitle;
    }

    public String getEmployeePhone() {
        return employeePhone;
    }

    public void setEmployeePhone(String employeePhone) {
        this.employeePhone = employeePhone;
    }

    public String getEmployeeEmail() {
        return employeeEmail;
    }

    public void setEmployeeEmail(String employeeEmail) {
        this.employeeEmail = employeeEmail;
    }

    public long getEmployeeDeptId() {
        return employeeDeptId;
    }

    public void setEmployeeDeptId(long employeeDeptId) {
        this.employeeDeptId = employeeDeptId;
    }

    public String getEmployeeDeptName() {
        return employeeDeptName;
    }

    public void setEmployeeDeptName(String employeeDeptName) {
        this.employeeDeptName = employeeDeptName;
    }

    public boolean ifFullyUseableEmployee() {
         return this.employeeId < 1 || this.employeeDeptId < 1 || this.employeeDeptName.length() < 1;
    }

    @Override
    public String toString() {
        return this.employeeTitle + " " + this.employeeName;
    }
}

A perhaps new class for the DatabaseHelper namely DeptDPhelper.java

public class DeptDPHelper extends SQLiteOpenHelper {

    SQLiteDatabase EmpDept;

    //<<<<<<<<<< BAD PRACTICE TO HARD CODE TABLE AND COLUMN NAMES THROUGHOUT >>>>>>>>>>
    //<<<<<<<<<< INSTEAD USE CONSTANTS                                       >>>>>>>>>>>

    public static final String DBNAME = "EmpDept";
    public static final int DBVERSION = 2;
    public static final String DEPARTMENT_TABLE = "department";
    public static final String EMPLOYEE_TABLE = "employee"; //<<<<<<<<<< not Employee to be consistent with naming connvention

    public static final String DEPARTMENT_DEPTID_COLUMN = "departmenttid";
    public static final String DEPARTMENT_NAME_COLUMN = "departmentname";

    public static final String EMPLOYEE_EMPID_COLUMN = "employeeid";
    public static final String EMPLOYEE_NAME_COLUMN = "employeename";
    public static final String EMPLOYEE_TITLE_COLUMN= "employeetitle";
    public static final String EMPLOYEE_PHONE_COLUMN = "employeephone";
    public static final String EMPLOYEE_EMAIL_COLUMN = "employeeemail";
    public static final String EMPLOYEE_DEPT_COLUMN = "employeeedepartmentid";

    public DeptDPHelper(Context context) {
        super(context, DBNAME, null, DBVERSION);
        EmpDept = this.getWritableDatabase();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String crt_dept_table_sql = "CREATE TABLE IF NOT EXISTS " + DEPARTMENT_TABLE + "(" +
                DEPARTMENT_DEPTID_COLUMN + " INTEGER PRIMARY KEY, " + //<<<<<<<<<< AUTOINCREMENT INEFFICIENT NOT NEEDED
                DEPARTMENT_NAME_COLUMN + " TEXT" +
                ")";
        db.execSQL(crt_dept_table_sql);

        String crt_employee_table_sql = "CREATE TABLE IF NOT EXISTS " + EMPLOYEE_TABLE + "(" +
                EMPLOYEE_EMPID_COLUMN + " INTEGER PRIMARY KEY, " +
                EMPLOYEE_NAME_COLUMN + " TEXT NOT NULL, " +
                EMPLOYEE_TITLE_COLUMN + " TEXT NOT NULL, " +
                EMPLOYEE_PHONE_COLUMN + " TEXT NOT NULL, " +
                EMPLOYEE_EMAIL_COLUMN + " TEXT NOT NULL, " +
                EMPLOYEE_DEPT_COLUMN + " INTEGER REFERENCES " + DEPARTMENT_TABLE + "(" +
                DEPARTMENT_DEPTID_COLUMN +
                ")" +
                ")";
        db.execSQL(crt_employee_table_sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        //<<<<<<<<<< IF USING FOREIGN KEYS AND SUPPORT IS ON THEN CANNOT DELETE PARENT TABLE FIRST >>>>>>>>>>
        //<<<<<<<<<< AS SUCH DEPARTMENT TABLE MUST BE DROPPED FIRST OTHEWISE THERE WILL BE CONFLICTS >>>>>>>>>>
        db.execSQL("DROp TABLE IF EXISTS " + EMPLOYEE_TABLE);
        db.execSQL("DROP TABLE IF EXISTS " + DEPARTMENT_TABLE);
        onCreate(db);
    }

    //<<<<<<<<<< FOREIGN KEY SUPPORT IS TUREND OFF BY DEFAULT SO TURN THEM ON >>>>>>>>>>
    //<<<<<<<<<< IF NOT USELESS CODING FOREIGN KEYS                           >>>>>>>>>>
    @Override
    public void onConfigure(SQLiteDatabase db) {
        db.setForeignKeyConstraintsEnabled(true);
        super.onConfigure(db);
    }

    public long insertEmployee(String name, String title, String phone, String email, long deptid) {
        //<<<<<<<<<< optional check if deptid references a deptartment >>>>>>>>>>
        //<<<<<<<<<< however INSERT OR IGNORE doesn't ignore FK conflicts >>>>>>>>>>
        if (!ifDepertmentExists(deptid)) return -1;

        ContentValues cv = new ContentValues();
        cv.put(EMPLOYEE_NAME_COLUMN,name);
        cv.put(EMPLOYEE_TITLE_COLUMN,title);
        cv.put(EMPLOYEE_PHONE_COLUMN,phone);
        cv.put(EMPLOYEE_EMAIL_COLUMN,email);
        cv.put(EMPLOYEE_DEPT_COLUMN,deptid);
        return EmpDept.insert(EMPLOYEE_TABLE,name,cv);
    }

    public long insertDepartment(String name) {
        ContentValues cv = new ContentValues();
        cv.put(DEPARTMENT_NAME_COLUMN,name);
        return EmpDept.insert(DEPARTMENT_TABLE,null,cv);
    }

    public Cursor selectLikeEmployeesByNamePart(String namepart) {
        String[] columns = new String[]{EMPLOYEE_NAME_COLUMN};
        String whereclause = EMPLOYEE_NAME_COLUMN + "LIKE ?";
        String[] whereargs = new String[] {"%" + namepart +"%"};
        return EmpDept.query(EMPLOYEE_TABLE,columns,whereclause,whereargs,null,null,EMPLOYEE_NAME_COLUMN);
    }

    public ArrayList<Employee> getAllEmployees(String namepart) {
        ArrayList<Employee> employees = new ArrayList<>();
        String whereclause = null;
        String[] wherargs = null;
        if (namepart != null && namepart.length() > 0) {
            whereclause = EMPLOYEE_NAME_COLUMN + " LIKE ?";
            wherargs = new String[]{"%" + namepart + "%"};
        }
        Cursor csr = EmpDept.query(EMPLOYEE_TABLE + " JOIN " + DEPARTMENT_TABLE + " ON " + EMPLOYEE_DEPT_COLUMN + "=" + DEPARTMENT_DEPTID_COLUMN,
                    null,whereclause, wherargs, null, null, EMPLOYEE_NAME_COLUMN + "," + EMPLOYEE_DEPT_COLUMN);
        while (csr.moveToNext()) {
            employees.add( new Employee(
                    csr.getLong(csr.getColumnIndex(EMPLOYEE_EMPID_COLUMN)),
                    csr.getString(csr.getColumnIndex(EMPLOYEE_NAME_COLUMN)),
                    csr.getString(csr.getColumnIndex(EMPLOYEE_TITLE_COLUMN)),
                    csr.getString(csr.getColumnIndex(EMPLOYEE_PHONE_COLUMN)),
                    csr.getString(csr.getColumnIndex(EMPLOYEE_EMAIL_COLUMN)),
                    csr.getLong(csr.getColumnIndex(DEPARTMENT_DEPTID_COLUMN)),
                    csr.getString(csr.getColumnIndex(DEPARTMENT_NAME_COLUMN)))
            );
        }
        csr.close();
        return employees;
    }


    private boolean ifDepertmentExists(long deptid) {
        String wherecluase = DEPARTMENT_DEPTID_COLUMN + "=?";
        String[] whereargs = new String[]{String.valueOf(deptid)};
        Cursor csr =EmpDept.query(DEPARTMENT_TABLE,null,wherecluase,whereargs,null,null,null);
        int rowcount = csr.getCount();
        csr.close();
        return rowcount > 0;
    }
}

Some comments have been added, which should explain some things.

The empDetails Activity namely empDetails.java

public class empDetails extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_emp_details);
        TextView name = (TextView)findViewById(R.id.textview7);
        TextView title = (TextView)findViewById(R.id.textview8);
        TextView phone = (TextView)findViewById(R.id.textview9);
        TextView email = (TextView)findViewById(R.id.textview10);
        TextView dept = (TextView)findViewById(R.id.textview11);
        Button mDoneButton = this.findViewById(R.id.donebutton);
        mDoneButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });
        name.setText(getIntent().getExtras().getString(DeptDPHelper.EMPLOYEE_NAME_COLUMN));
        title.setText(getIntent().getExtras().getString(DeptDPHelper.EMPLOYEE_TITLE_COLUMN));
        phone.setText(getIntent().getExtras().getString(DeptDPHelper.EMPLOYEE_PHONE_COLUMN));
        email.setText(getIntent().getExtras().getString(DeptDPHelper.EMPLOYEE_EMAIL_COLUMN));
        dept.setText(getIntent().getExtras().getString(DeptDPHelper.DEPARTMENT_NAME_COLUMN));
    }
}

And lastly MainActivity.java

public class MainActivity extends AppCompatActivity {

    DeptDPHelper mDBHlpr;
    ArrayList<Employee> mEmployeeList;
    ArrayAdapter mNameAdapter;
    ListView namelist;
    EditText mNamePart;
    TextWatcher mTW;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        namelist = this.findViewById(R.id.namelist);
        mNamePart = this.findViewById(R.id.searchbar);
        mDBHlpr = new DeptDPHelper(this);
        addSomeData();
        setupOrRefreshNameList();
        setupSearch();
    }

    private void setupOrRefreshNameList() {
        String namepart = mNamePart.getText().toString();
        if (namepart.length() < 1) namepart = null;
        if (mEmployeeList != null) {
            mEmployeeList.clear();
            ArrayList<Employee> el = mDBHlpr.getAllEmployees(namepart);
            mEmployeeList.addAll(el);
        } else {
            mEmployeeList = mDBHlpr.getAllEmployees(namepart);
        }
        if (mNameAdapter == null) {
            mNameAdapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1,mEmployeeList);
            namelist.setAdapter(mNameAdapter);
            setupListViewListeners();
        } else {
            mNameAdapter.notifyDataSetChanged();
        }
    }

    //<<<<<<<<<< For testing >>>>>>>>>>
    private void addSomeData() {
        long dept1 = mDBHlpr.insertDepartment("Dept001");
        long dept2 = mDBHlpr.insertDepartment("Dept002");

        mDBHlpr.insertEmployee("Fred","Mr.","1234567890","fred.x.com",dept1);
        mDBHlpr.insertEmployee("Fred","Mr.","0987654321","fred@z.com",dept2);
        mDBHlpr.insertEmployee("Mary","Ms.","9999999999","mary@marymail.net",dept1);
        mDBHlpr.insertEmployee("Albert","Sir ", "1113334445","lord@roayls.org",dept1);
    }

    private void setupListViewListeners() {
        namelist.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Employee e = (Employee) mNameAdapter.getItem(i);
                Toast.makeText(
                        getApplicationContext(),
                        "You clicked on " +
                                e.getEmployeeTitle() + " " +
                                e.getEmployeeName() +
                                " ID=" + String.valueOf(e.getEmployeeId()) +
                                " Email=" + e.getEmployeeEmail() +
                                " Phone=" + e.getEmployeePhone() +
                                " Dept=" + e.getEmployeeDeptName()
                        ,
                        Toast.LENGTH_SHORT)
                        .show();
                Intent intent = new Intent(MainActivity.this,empDetails.class);
                intent.putExtra(DeptDPHelper.EMPLOYEE_NAME_COLUMN,e.getEmployeeName());
                intent.putExtra(DeptDPHelper.EMPLOYEE_EMPID_COLUMN,e.getEmployeeId());
                intent.putExtra(DeptDPHelper.EMPLOYEE_TITLE_COLUMN,e.getEmployeeTitle());
                intent.putExtra(DeptDPHelper.EMPLOYEE_PHONE_COLUMN,e.getEmployeePhone());
                intent.putExtra(DeptDPHelper.EMPLOYEE_EMAIL_COLUMN,e.getEmployeeEmail());
                intent.putExtra(DeptDPHelper.DEPARTMENT_NAME_COLUMN,e.getEmployeeDeptName());
                startActivity(intent);
            }
        });
    }

    private void setupSearch() {
        mTW = new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            //<<<<<<<<<< Every time the text is changed refresh the ListView >>>>>>>>>>
            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                setupOrRefreshNameList();
            }

            @Override
            public void afterTextChanged(Editable editable) {

            }
        };
        mNamePart.addTextChangedListener(mTW);
    }
}

Note this dynamically alters the list as you enter text into the EditText
Note that the Mainifest includes <activity android:name=".empDetails"></activity>

When first run you get :-

Entering A for example (note only applies to the name not the title part):-

Clicking on Mary :-

Done will return to the MainActivity.

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