Question

so I’ve been making mathematical programs for Android for a while, and I’ve come across a problem where i need to print a range of numbers using a for loop, I’m not sure how to enable my program to print the variables the way I’d like, I’ve tried TextView, but it only shows the first variable, do I need to use ListView? and how do set the text into it? here’s my xml and code files that I’ve tried so far:

class:

public class Screen extends ListActivity {

public EditText txtbound1;
private double a = 0;
private double b1 = 0;
private double c = 0;

//LIST OF ARRAY STRINGS WHICH WILL SERVE AS LIST ITEMS
ArrayList<String> listItems=new ArrayList<String>();

//DEFINING STRING ADAPTER WHICH WILL HANDLE DATA OF LISTVIEW
ArrayAdapter<String> adapter;



@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.screen1);
    Bundle b = getIntent().getExtras(); 
    double bound = b.getDouble("name");

    adapter=new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1,
            listItems);
        setListAdapter(adapter);



    //METHOD WHICH WILL HANDLE DYNAMIC INSERTION
    //public void addItems(View v) {
    // listItems.add("Clicked : "+clickCounter++);
    // adapter.notifyDataSetChanged();



    for(double i = bound;i>0;i--)
    {
                    a = bound;
                    b1 = a * 2;
                    c = a*3;
                    bound--;

}
}
    public void addItems(double a, double b1, double c) { // or you can parse it before and have string parameters
         listItems.add(Double.toString(a) + " " + Double.toString(b1) + " " + Double.toString(c));
         adapter.notifyDataSetChanged();

         }
     }

and layout is:

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<Button
android:id="@+id/addBtn"
android:text="Add New Item"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="addItems"/>

<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:drawSelectorOnTop="false"
/>
</LinearLayout>

so lets say the user inputs 5 as bound, I’d like to to be displayed as such:

• A B C
• 5 10 15
• 4 8 12
• 3 6 9
• 2 4 6
• 1 2 3

however it only displays the 5 10 and 15 line, how do I edit the for loop so it works? Do i need to set a, b1 and c as an array ? or will ListView work? I’ve never used ListView before so if ListView is what I need please show me how to initialise it in the xml layout and how to print the variables to it as I’ve done previous, Thanks

Answer 1

Yes, it makes more sense if you do use a Listview. Checkout this post

Where on the suggested “addItems” method, a simple concatenation will suffice:

public void addItems(double a, double b1, double c) { // or you can parse it before and have string parameters
 listItems.add(Double.toString(a) + " " + Double.toString(b1) + " " + Double.toString(c));
 adapter.notifyDataSetChanged();
}