如何在TextView中显示ArrayList中的字符串

Question

I need to display current values in TextView (after removing String). I'm adding String when button is On and I need to remove it, when it's Off ( I don't know if I do it well), next I need to display Strings in TextView without deleted String. I need to display only Strings from On buttons. Here is my code:

public class Calc extends ActionBarActivity {

    TextView display;

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

        display = (TextView)findViewById(R.id.textView2);
        display.setText("Add item");
    }

    static boolean isempty=true;

    public void changeButton(View sender) {
    ToggleButton btn = (ToggleButton) sender;

    ArrayList<String> mActiveToggles = new ArrayList<String>();

    String b = btn.getText().toString();

    boolean on = ((ToggleButton) sender).isChecked();

    if(on) {
        if (isempty) {
            if (b.equals("0")) return;
            display.setText(btn.getText());
            mActiveToggles.add(b);
            isempty = false;
        } else {
            display.append(btn.getText());
            mActiveToggles.add(b);
        }
    }
    else
    {
        if (b.equals(btn.getText()))
        {
            mActiveToggles.remove(b);
            display.setText(mActiveToggles.toString());

        }
    }
}

Answer 1

Edit based on new information:

To display the texts from all the toggles that are currently ON in your TextView I suggest that you create a

private ArrayList<String> mActiveToggles = new ArrayList<String>();

Whenever a toggle button is set to ON, you add the label of that toggle button to the list. Whenever a toggle button is set to OFF, you remove the label from the list.

if(on) {
    if (b.equals("0")) return; // Don't really know why you need this one...

    // If the button is ON, add its text label to the list.
    mActiveToggles.add(btn.getText());
} else {
    // If button is OFF, remove its text label from the list.
    mActiveToggles.remove(btn.getText());
}

To update your TextView simple iterate over the items in the list and add them to the TextView (with an appropriate separator). Something like this:

StringBuilder allLabels = new StringBuilder();
for(String s : mActiveToggles) {
    if(allLabels.length() > 0) {
        allLabels.append(" "); // some divider between the different texts
    }
    allLabels.append(s);
}
display.setText(allLabels.toString());

If you really do need the content of your TextView to be persistently stored, iterate over the list items and concatenate them and then store them to your SharedPreferences object. Restoring them from storage would simply be the reverse operation of splitting the String and populating the list. Based on the code that you've provided I don't see a need for this, but there could of course be more to it than what you've posted here.

Answer 2

For getting strings from shared preferences you have to use :

if(sharedpreferences.contains(key_value)){
textview.setText(sharedpreferences.getString(key_value, null));
}

If there any issue you get please let me know.