单击按钮时android更改列表视图内的图像视图

Question

I know that this question might be a duplicate of another question but i tried to follow what was suggested in solutions to similar questions without any success. I am relatively new to android so please kindly point me in the right direction.

Scenario: I have a list view that has a custom layout file containing a small image and a text view. The list view displays all items as intended but what I want to do is as follows: When a button is clicked, a condition is evaluated and if the result is true, i want to change the default image to another one. I am aware that I have to perform the image switching in the get view method that I have to override.

public View getView(int position, View convertView, ViewGroup parent) {
            View itemView=convertView;
            if (itemView==null) {
                itemView=getLayoutInflater().inflate(R.layout.check_list_view, parent, false);
            }
            MailObject currentMailObject=mailList.get(position);
            ImageView ivCurrentMail=(ImageView)itemView.findViewById(R.id.ivMailIcon);
            if (mailList.get(position).isScanned()) {
                ivCurrentMail.setImageResource(R.drawable.ic_mail_scanned);

            }


            return itemView;
        }

The code for the button is:

btnSave.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Toast.makeText(getApplicationContext(), scanResult, Toast.LENGTH_LONG).show();

            if(!scannedMails.contains(scanResult))
            {
                scannedMails.add(scanResult);
                for (int i = 0; i < mailList.size(); i++) {
                    if (mailList.get(i).getCode().equalsIgnoreCase(scanResult)) {
                        int position=i;
                        mailList.get(i).setScanned(true);

                        ImageView ivCurrent = (ImageView) lvMails.getAdapter().getView(position, null, null).findViewById(R.id.ivMailIcon);
                        ivCurrent.setImageResource(R.drawable.ic_mail_scanned);

                        lvMails.invalidateViews();

                    }
                }

            }           






        }
    });

The XML file for a list view item is as follows:

<ImageView
    android:id="@+id/ivMailIcon"
    android:layout_width="30dp"
    android:layout_height="30dp"
    android:src="@drawable/ic_mail_not_scanned" />

    <TextView
        android:id="@+id/tvMailItem"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="17dp"
        android:layout_toRightOf="@+id/ivMailIcon"
        android:text="Medium Text"
        android:textAppearance="?android:attr/textAppearanceMedium" />

</RelativeLayout>

I did test if the condition evaluates as it should by displaying a Toast message on list view item click and the results were positive but the image just does not change. Please let me know where I went wrong or missed something. Thanks

Answer 1

You're setting the same image twice. In both cases, you use the setImageResource() method for the ImageView that points to R.id.ivMailIcon to set the drawable as R.drawable.ic_mail_scanned .

You are probably "setting" to image again correctly on a click, but since it's the same image, it won't appear to change.