Android：如何从MainActivity的视图分页器片段增加徽章？

Question

我在MainActivity创建了徽章。它完美地从活动中完成。但在MainActivity中，我已经ViewPager，我需要增加片段的徽章数量。知道如何实现这个目标吗？

  @Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.cart_menu, menu);

    menuItem = menu.findItem(R.id.action_cart);
    menuItem.setIcon(buildCounterDrawable(count, R.drawable.ic_cart));

    return true;
}

  @Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

    if (id == R.id.action_cart) {
        Intent intent = new Intent(this, CartActivity.class);
        intent.putExtra("id", orderid);
        startActivityForResult(intent, PICK_REQUEST);
        return true;
    }

    return super.onOptionsItemSelected(item);
}

这是徽章计数增量

的方法

   private Drawable buildCounterDrawable(int count, int backgroundImageId) {
    LayoutInflater inflater = LayoutInflater.from(this);
    View view = inflater.inflate(R.layout.counter_menuitem_layout, null);
    view.setBackgroundResource(backgroundImageId);

    if (count == 0) {
        View counterTextPanel = view.findViewById(R.id.counterValuePanel);
        counterTextPanel.setVisibility(View.GONE);
    } else {
        TextView textView = (TextView) view.findViewById(R.id.count);
        textView.setText(String.valueOf(count));
    }

    view.measure(
            View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
            View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
    view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());

    view.setDrawingCacheEnabled(true);
    view.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
    Bitmap bitmap = Bitmap.createBitmap(view.getDrawingCache());
    view.setDrawingCacheEnabled(false);

    return new BitmapDrawable(getResources(), bitmap);
}

public void doIncrease(int val) {
    count = val;
    invalidateOptionsMenu();
}

单击加号按钮，我需要增加计数。完全没有意识到如何实现这个

Answer 1

首先创建一个新的接口类

public interface OnStepCompletedListener {
     void onStepCompleted(int position);
}

现在在Activity类中实现此接口。

public class MainActivity extends AppCompatActivity implements OnStepCompletedListener{

并实施该方法（在您的活动中）

@Override
public void onStepCompleted(int position){
//
// invoke method to change the badge number here
//
}

现在在你的片段里面。将此代码添加到您想要更改徽章的位置。（在＆＃39; +＆＃39;按钮点击内）

try{
     ((OnStepCompletedListener) getActivity()).onStepCompleted(0);
//This will invoke the implemented method in your activity class. You 
//can pass any type of value through to your activity. Just add the 
//parameter in your interface declaration.
}catch (ClassCastException e){
     e.printStackTrace();
}

Answer 2

将count变量定义为static并从菜单布局类访问它，从而将静态计数的值放到textview上。 我已经从片段中添加了菜单，这是代码：

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setHasOptionsMenu(true);
}

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    // TODO Add your menu entries here
    super.onCreateOptionsMenu(menu, inflater);
}