SQLite Database for Commenting function - sqlite

Question

There is no errors with the codes. However, I am trying to build a comment section where the name and comments will be saved in the database(SQLite).
1) It does not stay in the Textview after i come back from another page.
2) Example, i commented once, and the comment shows. I comment again, it actually re-displays the previous and the new comments together.
public class BuyerHome extends AppCompatActivity {
DatabaseHelper2 myDB;
//EditText name,comment;
EditText nameIn;
EditText commentIn;
TextView viewComment;
Button postComment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_buyer_home);
nameIn = (EditText) findViewById(R.id.nameInput);
commentIn = (EditText) findViewById(R.id.commentText);
viewComment = (TextView) findViewById(R.id.viewCommentText);
myDB = new DatabaseHelper2(this);
postComment = (Button) findViewById(R.id.buttonComment);
postComment.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String name = nameIn.getText().toString();
String comment = commentIn.getText().toString();
if(nameIn.length()!=0 && commentIn.length()!=0){
AddData(name,comment);
nameIn.setText("");
commentIn.setText("");
}else{
Toast.makeText(BuyerHome.this, "Insert fields",
Toast.LENGTH_SHORT).show();
}
Cursor data = myDB.getContents();
if(data.getCount()==0){
Toast.makeText(BuyerHome.this, "Database empty",
Toast.LENGTH_SHORT).show();
}
else{
while(data.moveToNext()){
viewComment.append(data.getString(1));
viewComment.append(data.getString(2)+"\n");
}
}
//viewComment.append("\n"+name+":"+comment);
}
});
}
public void AddData(String name,String comment){
boolean insertData = myDB.insertData(name,comment);
if(insertData==true){
Toast.makeText(this, "Success", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(this, "Fail", Toast.LENGTH_SHORT).show();
}
}
}
1) I would like the past comments to be there as long as the page is available.
2) I would like only the latest comment to be displayed(on top of the past comments), and not the past comments(re-displaying again) with the new comment.

Answer 1

I'd suggest perhaps using a second view for the older comments. You would also need a means of determining the latest as opposed to older comments.
In the example below the second view is a Listview (this would enable you to click on a specific message, perhaps quoting it, perhaps extracting the name).
The example caters for two ways of determining the last posted comment via the id column (note _id is actually used as the column name as this then allows a Cursor Adapter to be used for the ListView which can be advantageous).
To facilitate showing the comments after returning the onResume method has been overridden inn the activity.
here's the code :-
DatabaseHelper2.java
public class DatabaseHelper2 extends SQLiteOpenHelper {
private final static String DBNAME = "buyerdb";
private final static int DBVERSION = 1;
public final static String TBL_COMMENT = "comment";
public final static String COL_COMMENT_ID = BaseColumns._ID;
public final static String COL_COMMENT_NAME = "name";
public final static String COL_COMMENT_COMMENT = "comment";
public final static String COl_COMMENT_TIMESTAMP = "timestamp";
private String crt_tbl_comment = "CREATE TABLE IF NOT EXISTS " + TBL_COMMENT + "(" +
COL_COMMENT_ID + " INTEGER PRIMARY KEY, " +
COL_COMMENT_NAME + " TEXT," +
COL_COMMENT_COMMENT + " TEXT, " +
COl_COMMENT_TIMESTAMP + " TEXT DEFAULT CURRENT_TIMESTAMP" +
")";
SQLiteDatabase mDB;
public DatabaseHelper2(Context context) {
super(context, DBNAME, null, DBVERSION);
mDB = this.getWritableDatabase();
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(crt_tbl_comment);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public long addData(String name, String comment) {
ContentValues cv = new ContentValues();
cv.put(COL_COMMENT_NAME,name);
cv.put(COL_COMMENT_COMMENT,comment);
return mDB.insert(TBL_COMMENT,null,cv);
}
public Cursor getLatestComment() {
return mDB.query(TBL_COMMENT,null,null,null,null,null,COl_COMMENT_TIMESTAMP + " DESC","1");
}
public Cursor getAllButLatestComment() {
String whereclause = COL_COMMENT_ID + " < (SELECT max(" +
COL_COMMENT_ID +
") FROM " + TBL_COMMENT +
")";
return mDB.query(TBL_COMMENT,null,whereclause,null,null,null,COl_COMMENT_TIMESTAMP + " DESC");
}
}
Note that the timestamp column hasn't been utilised but could be, as when a row (a comment) is added the current timestamp will automatically be used to set the column.
Note the getLatestComment and the getAllButLatestComment methods return a Cursor with the appropriate rows.
BuyerHome.java
public class BuyerHome extends AppCompatActivity {
EditText nameIn;
EditText commentIn;
TextView viewComment;
Button postComment;
ListView olderComments; //<<<<<<<<<< Added (Listview needs to be added to the layout)
DatabaseHelper2 myDB;
Cursor oldermessages, latestmessage; //<<<<<<<<<< Added
SimpleCursorAdapter sma; //<<<<<<<<<< Added adapter for the ListView
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_buyer_home);
nameIn = (EditText) findViewById(R.id.nameInput);
commentIn = (EditText) findViewById(R.id.commentText);
viewComment = (TextView) findViewById(R.id.viewCommentText);
olderComments = (ListView) findViewById(R.id.olderComments); //<<<<<<<<<< Added
myDB = new DatabaseHelper2(this);
postComment = (Button) findViewById(R.id.buttonComment);
postComment.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String name = nameIn.getText().toString();
String comment = commentIn.getText().toString();
if (nameIn.length() != 0 && commentIn.length() != 0) {
myDB.addData(name, comment); //<<<<<<<<<< method starts changed lower case a
nameIn.setText("");
commentIn.setText("");
} else {
Toast.makeText(BuyerHome.this, "Insert fields",
Toast.LENGTH_SHORT).show();
}
displayComments(); //<<<<<<<<<< added to refresh the display according to the latest comments
}
});
}
//<<<<<<<<<< ADDED so will display comments whenever called including returning from another activity
#Override
protected void onResume() {
super.onResume();
displayComments();
}
//<<<<<<<<<< ADDED entire method for displaying comments
private void displayComments() {
latestmessage = myDB.getLatestComment();
if (latestmessage.moveToFirst()) {
viewComment.setText(latestmessage.getString(latestmessage.getColumnIndex(DatabaseHelper2.COL_COMMENT_NAME)) +
" said :- " +
latestmessage.getString(latestmessage.getColumnIndex(DatabaseHelper2.COL_COMMENT_COMMENT)));
} else {
viewComment.setText("");
}
oldermessages = myDB.getAllButLatestComment();
if (sma == null) {
sma = new SimpleCursorAdapter(
this,
android.R.layout.simple_list_item_2,oldermessages,
new String[]{DatabaseHelper2.COL_COMMENT_NAME,DatabaseHelper2.COL_COMMENT_COMMENT},
new int[]{android.R.id.text1,android.R.id.text2},
0
);
olderComments.setAdapter(sma);
} else {
sma.swapCursor(oldermessages);
}
}
}
Result
The highlighted line is the latest comment.
The latest comment is followed by the list of all other comments.