Android adapter not updating ui

问题

I have a class witch holds some variables...eg

 int yellow = 0xffffff66;
 int green = 0xff00EE76;
 int red = 0xffff4342;
 int blue = 0xff42c3ff;
 int purple = 0xff9932CC;
 int white = 0xffffffff;
 ArrayList<Integer>nextColorArray = new ArrayList<Integer>();

int total_count = 0;

in my onCreate method:

GridView gridview2 = (GridView) findViewById(R.id.colorNext);
gridview2.setAdapter(new ImageAdapter(this));
nextColorArray.add(blue);
nextColorArray.add(green);
nextColorArray.add(red);
nextColorArray.add(yellow);
nextColorArray.add(purple);

from my adapter i add elements to the grid view to produce 5 colors the show in the gridview UI no problem... o.k

i have a button onclick(not in onCreate) event that increments total_count by 1 each time i click the button...o.k when the total_count is greater than ten i want to add a new element to the array..ok

if (action == MotionEvent.ACTION_DOWN) {
   if(total_Count > 10){
       nextColorArray.add(0, white);  
}...ok

my problem is that the UI gridview is not updating the ui to show the new color...any ideas on how i can update the adapter when a new color is added to the list????

Edit: Since i am not sure how many edit's i made to my post. i edited the question and added the answer here. This works .

public class MainActivity extends Activity {
int yellow = 0xffffff66;
int green = 0xff00EE76;
int red = 0xffff4342;
int blue = 0xff42c3ff;
int purple = 0xff9932CC;
int white = 0xFFFFFFFF;

int total_Count = 0;
int colorPosition = 0;
int colorPickerStart = 0;
Button button;

ImageView imageView;

ImageAdapter ia;
GridView gridview2;

ArrayList<Integer>nextColorArray = new ArrayList<Integer>(10);
ArrayList<Integer>colorPicker = new ArrayList<Integer>();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nextColorArray.add(blue);
nextColorArray.add(green);
nextColorArray.add(red);
nextColorArray.add(yellow);
nextColorArray.add(purple);
//set adapters
GridView gridview = (GridView) findViewById(R.id.gridview);
gridview.setAdapter(new ButtonAdapter(this));
button = (Button) findViewById(R.id.button1); 
gridview2 = (GridView) findViewById(R.id.gridview2);
ia = new ImageAdapter(this, nextColorArray);
gridview2.setAdapter(ia);
button.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(View arg0) {

                        nextColorArray.add(Color.BLACK);
                        ia.notifyDataSetChanged();

            }
        });
//next color elements


}
public class ImageAdapter extends BaseAdapter {
private Context mContext;
ArrayList<Integer> a;

public ImageAdapter(Context c, ArrayList<Integer> a) {
    mContext = c;
    this.a = a;
}
public int getCount() {

    return a.size();
}

public Object getItem(int position) {
    return position;
}

public long getItemId(int position) {
    return 0;
}

/*create a new ImageView for each item referenced by the Adapter*/
public View getView(int position, View convertView, ViewGroup parent) {
    if (convertView == null) {/*if it's not recycled, initialize some attributes*/
        imageView = new ImageView(mContext);
        imageView.setLayoutParams(new GridView.LayoutParams(50, 45));
        imageView.setBackgroundColor(nextColorArray.get(colorPosition));
        if(colorPosition < 9) colorPosition++;
    } else {
        imageView = (ImageView) convertView;
    }
    return imageView;
}

}
/*button adapter*/
public class ButtonAdapter extends BaseAdapter {
private Context mContext;

public ButtonAdapter(Context c) {
    mContext = c;
}

public int getCount() {

    return nextColorArray .size();
}

public Object getItem(int position) {
    return position;
}

public long getItemId(int position) {
    return 0;
}

// create a new button for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {

    if (convertView == null) {

        button = new Button(mContext);
        button.setLayoutParams(new GridView.LayoutParams(128, 128));

        total_Count++;
        button.setText(""+total_Count); 
    } else {
        button = (Button) convertView;
    }
    return button;
}// end get view
}// end button adapter

activity_main

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<GridView
    android:id="@+id/gridview"
    android:layout_width="fill_parent"
    android:layout_height="150dp"
    android:columnWidth="0dp"
    android:gravity="center"
    android:numColumns="2"
    android:horizontalSpacing="20dp"
    android:padding="40dp"
    android:verticalSpacing="20dp" />
     <GridView
    android:id="@+id/gridview2"
    android:layout_width="fill_parent"
    android:layout_height="150dp"
    android:layout_above="@+id/button1"
    android:layout_alignParentRight="true"
    android:layout_marginBottom="74dp"
    android:columnWidth="0dp"
    android:gravity="center"
    android:horizontalSpacing="20dp"
    android:numColumns="2"
    android:padding="40dp"
    android:verticalSpacing="20dp" >
</GridView>


<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:text="Button" />


</RelativeLayout>

回答1:

You have to call notifyDataSetChanged() on your adapter in order to refresh its content.

回答2:

 ImageAdapter ia;
 GridView gridview2 = (GridView) findViewById(R.id.colorNext);
 ia = new ImageAdapter(this);
 gridview2.setAdapter(ia);  
 .... 
 if (action == MotionEvent.ACTION_DOWN) {
 if(total_Count > 10){
   nextColorArray.add(0, white); 
   ia.notifyDataSetChanged(); // call notifyDataSetChanged  to update your gridview
 }

public void notifyDataSetChanged ()

Notifies the attached observers that the underlying data has been changed and any View reflecting the data set should refresh itself.

Example:

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<GridView
    android:id="@+id/gridview"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:columnWidth="0dp"
    android:gravity="center"
    android:numColumns="2"
    android:horizontalSpacing="20dp"
    android:padding="40dp"
    android:verticalSpacing="20dp" />

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:text="Button" />

    </RelativeLayout>

MainActivity

  public class MainActivity extends Activity {

ImageAdapter im;
ImageView imageView;
GridView gd;
 ArrayList<Integer>nextColorArray = new ArrayList<Integer>(); 
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

     int yellow = 0xffffff66;
     int green = 0xff00EE76;
     int red = 0xffff4342;
     int blue = 0xff42c3ff;
     int purple = 0xff9932CC;
     final int white = 0xffffffff;
     nextColorArray.add(blue);
     nextColorArray.add(green);
     nextColorArray.add(red);
     nextColorArray.add(yellow);
     nextColorArray.add(purple);
        gd= (GridView) findViewById(R.id.gridview);
        im = new ImageAdapter(this,nextColorArray);
        gd.setAdapter(im);
     Button b= (Button) findViewById(R.id.button1);
     b.setOnClickListener(new OnClickListener()
     {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            nextColorArray.add(Color.BLACK);
            im.notifyDataSetChanged();

        }

     });
}
}

ImageAdapter

   public class ImageAdapter extends BaseAdapter{

Context mContext;
ArrayList<Integer> a;

public ImageAdapter(Context context,ArrayList<Integer> a)   {
    mContext=context;
    this.a= a;
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return a.size();
}

@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return position;
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return position;
}

@Override
public View getView(final int position, View arg1, ViewGroup arg2) {
     ImageView imageView;
        if (arg1 == null) {  
            imageView = new ImageView(mContext);

            imageView.setPadding(0, 20, 0, 0);
        } else {
            imageView = (ImageView) arg1;
        }

        imageView.setBackgroundColor(a.get(position));

        return imageView;

}
 }

As and when you click black color appears on the screen.

SnapShot

来源：https://stackoverflow.com/questions/16652812/android-adapter-not-updating-ui

标签

android

gridview

android-adapter