Passing Arraylist values into Edit Text Fields

[david foley]

Hi All,

just wondering what am i doing wrong here ? i am trying to Create a Random Number from 1-45 and add that to the Array and from there output it to my Edit Text Fields.

package com.example.dfoley.lotterynumbergenerator;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import java.util.ArrayList;

public class MyActivity extends Activity
{
    Button Generate;
    EditText editText, editText2, editText3, editText4, editText5, editText6;



   RandomMath page = new RandomMath();
   ArrayList<Integer> rand = page.getList();

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




        Generate = (Button) findViewById(R.id.NumberGenerate);
        editText = (EditText) findViewById(R.id.editText);
        editText2 = (EditText) findViewById(R.id.editText2);
        editText3 = (EditText) findViewById(R.id.editText3);
        editText4 = (EditText) findViewById(R.id.editText4);
        editText5 = (EditText) findViewById(R.id.editText5);
        editText6 = (EditText) findViewById(R.id.editText6);

        Generate.setOnClickListener(new View.OnClickListener() {



            public void onClick(View v)
            {

                /**int n = numberGenerate.nextInt(45)+1;
                int n2 = numberGenerate.nextInt(45)+1;
                int n3 = numberGenerate.nextInt(45)+1;
                int n4 = numberGenerate.nextInt(45)+1;
                int n5 = numberGenerate.nextInt(45)+1;
                int n6 = numberGenerate.nextInt(45)+1;*/


                    editText.setText(String.valueOf(rand.get(i)));
                    editText2.setText(String.valueOf(rand.get(i)));
                    editText3.setText(String.valueOf(rand.get(i)));
                      editText4.setText(String.valueOf(rand.get(i)));
                       editText5.setText(String.valueOf(rand.get(i)));
                      editText6.setText(String.valueOf(rand.get(i)));
                }


        });
    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.my, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

package com.example.dfoley.lotterynumbergenerator;
import java.util.ArrayList;
import java.util.Random;

public class RandomMath
{
    public ArrayList<Integer> myList;

    public RandomMath()
    {
        Random r;
        r = new Random();
        for (int i = 0; i <= 6; i++) {
            i = r.nextInt(45);
            myList.add(i);

        }
    }

    public ArrayList<Integer> getList()
    {
        return myList;
    }


}

[Ulf Dittmer]

What makes you think you're doing something wrong? What happens if you run this code, and how is that different from what you were expecting?

[david foley]

for starters

    editText.setText(String.valueOf(rand.get(i)));
                    editText2.setText(String.valueOf(rand.get(i)));
                    editText3.setText(String.valueOf(rand.get(i)));
                      editText4.setText(String.valueOf(rand.get(i)));
                       editText5.setText(String.valueOf(rand.get(i)));
                      editText6.setText(String.valueOf(rand.get(i)));

Its Showing me cannot resolve symbol "i"

i did try

                for(int i=0; i<=rand.size() ; i++ )
                {

                    editText.setText(String.valueOf(rand.get(i)));
                    editText2.setText(String.valueOf(rand.get(i)));
                    editText3.setText(String.valueOf(rand.get(i)));
                    editText4.setText(String.valueOf(rand.get(i)));
                    editText5.setText(String.valueOf(rand.get(i)));
                    editText6.setText(String.valueOf(rand.get(i)));
                }

                }

The App will Crash on Start up logCat is showing nothing

[Ulf Dittmer]

The first snippet won't compile because it uses a variable that is not defined - i.

The second has two problems - it runs as long as "i<=rand.size()", which is one iteration too long ("i<rand.size()" would be the correct clause), but even then it doesn't achieve the objective since it sets the same value in all 6 fields (which I'm guessing is not what you want).

I advise to use the first code snippet with "i" replaced by 0 to 5, respectively. Since the names of the 6 fields are hardcoded, you can't easily treat them in a loop anyway.

[david foley]

so you are saying something like this

                    editText.setText(String.valueOf(rand.get(0)));
                    editText2.setText(String.valueOf(rand.get(1)));
                    editText3.setText(String.valueOf(rand.get(2)));
                    editText4.setText(String.valueOf(rand.get(3)));
                    editText5.setText(String.valueOf(rand.get(4)));
                    editText6.setText(String.valueOf(rand.get(5)));

would Random Math do better?

[Ulf Dittmer]

It doesn't change anything about how the math is done, it merely changes how the results in "rand" are retrieved.

[david foley]

So for me to be able to Generate a Random Number from 0 - 45 six times and store that into my ArrayList
And then pass it on from its java.class to my MyActivity Class.

im declearing my RandomMath Page Class by
RandomMath page = new RandomMath();

i am also declearing my Arraylist. and the Method getList()
ArrayList<Integer> rand = page.getList();

[Ulf Dittmer]

I'm not sure if that's meant as a question (and if it is, what the question might be). Does it work? At a cursory glance it seems that it should.

[david foley]

Ulf Dittmer wrote:I'm not sure if that's meant as a question (and if it is, what the question might be). Does it work? At a cursory glance it seems that it should.

ok it could be that i was getting a
Null Pointer Exception on Randommath.class

[Ulf Dittmer]

Oh right, there are a couple of problems in that class. You're not creating an object in line 7 for "myList" to point to. That's why line 15 would throw an NPE.

And in line 14/15 you're clobbering the value of the loop variable "i". Something like "myList.add(r.nextInt(45))" would fix that.

[david foley]

package com.example.dfoley.lotterynumbergenerator;
import java.util.ArrayList;
import java.util.Random;

public class RandomMath
{
    public ArrayList<Integer> myList = new ArrayList<Integer>(6);

    public RandomMath()
    {
        Random r;
        r = new Random();
        for (int i = 0; i <=myList.size(); i++) {
          //  i = r.nextInt(45);
            myList.add(r.nextInt(45));

        }
    }

    public ArrayList<Integer> getList()
    {
        return myList;
    }

so now trying to get that pointed to my EditText Fields

[Ulf Dittmer]

I think there's now a problem in line 13 - the loop will run indefinitely, because "myList.size()" is dynamically evaluated, and will constantly increase. Something like "i < 6" would add exactly 6 elements to the list.

You probably assumed that the "6" in line 7 is the size of the list, but it's not, it's the initial capacity (which is not related to the size of the list).