Data positioning in a TableLayout - Android Studio

Question

I have two activities (A and B), activity A asks for a text input (string) and activity B stores that string in a table. What I wish to achieve: every time I add a new string into the table, the previous string moves down one row and the new string takes the old string's place. I also wish to save the table layout in activity B every time I return to activity A. How would I go about achieving this ?

Answer 1

Updated - Input activity

public class MainActivity extends AppCompatActivity {

    public static String PREFS_NAME = "prefs";
    public static String VALUES_KEY = "vals";

    EditText editText;
    SharedPreferences prefs;

    @Override
    protected void onStart() {
        super.onStart();
        prefs = getSharedPreferences(PREFS_NAME, MODE_PRIVATE);
    }

    private void addValue(Object s) {
        prefs.edit()
                .putString(VALUES_KEY, String.valueOf(s))
                .apply();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_edit_btn);

        editText = (EditText) findViewById(R.id.editText);

        findViewById(R.id.button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String s = editText.getText().toString();
                JSONArray arr = new JSONArray();

                // Just for testing
                if (s.equals("clear")) {
                    addValue(arr);
                    Toast.makeText(MainActivity.this, "prefs cleared", Toast.LENGTH_SHORT).show();
                    return;
                }
                String jsonString = prefs.getString(VALUES_KEY, arr.toString());

                // Store a JSON array
                try {
                    arr = new JSONArray(jsonString);
                    arr.put(s);
                    addValue(arr);
                } catch (JSONException e) {
                    e.printStackTrace();
                }

                // Go to next activity
                startActivity(new Intent(MainActivity.this, TableLayoutActivity.class));

            }
        });
    }
}

Second activity - Has the table

public class TableLayoutActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_tablelayout);

        SharedPreferences prefs = getSharedPreferences(MainActivity.PREFS_NAME, MODE_PRIVATE);

        TableLayout tl = (TableLayout) findViewById(R.id.table);

        // Get the array out of preferences
        JSONArray arr = new JSONArray();
        String jsonString = prefs.getString(MainActivity.VALUES_KEY, arr.toString());

        LayoutInflater inflater = LayoutInflater.from(this);
        try {
            arr = new JSONArray(jsonString);
            // Loop backwards over list, adding rows
            for (int i = arr.length() - 1; i >= 0; --i) {
                View rowView = inflater.inflate(R.layout.table_row, tl, false);
                TextView rowText = (TextView) rowView.findViewById(android.R.id.text1);

                rowText.setText( i + ": " + arr.getString(i));
                tl.addView(rowView,
                        TableLayout.LayoutParams.MATCH_PARENT,
                        TableLayout.LayoutParams.WRAP_CONTENT);
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}

Original Answer

every time I add a new string into the table, the previous string moves down one row and the new string takes the old string's place

I'm not seeing a TableLayout or TableRow in your question. There are three constant strings, but the order you want to display those in seems unclear.

But here's an approach... You store a List of Strings in SharedPreferences or database, whatever. You pass that list of strings to the Activity with the TableLayout tl = (TableLayout) findViewById(R.id.tableLayout).

From there, you can simply loop backwards for (int i = list.size(); i >=0; i--), get String s = list.get(i);, then generate a TableRow tr = new TableRow() which you'll add some TextView that you've setText(s) on it. (Or inflate some XML file containing both the TextView and TableRow).

When you are done building TableRow tr, then you can

tl.addView(tr, new TableLayout.LayoutParams(
    TableLayout.LayoutParams.FILL_PARENT, 
    TableLayout.LayoutParams.WRAP_CONTENT));

Thereby, doing what I've quoted above.