如何从BaseAdapter Android获取活动变量

Question

Im having a variable, bill_id on MainActivity. Then on MainActivity , I also has list view category, i put onItemClick on CategoryListAdapter. Here, when i click the category i want to reload the activity, which is new intent , and also pass variables, i want to pass category_id and bill_id (which is from MainActivity )

how can i get bill_id value from BaseAdapter ?

here my snippet:

final int category_id = listData.get(position).getID();
        final String category_name = listData.get(position).get_name();

        holder.btnCategory.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v){
                Log.d(TAG, "click category:"+category_id);
                Log.d(TAG, "category selected:"+category_name);

                // get cat id, reload with its id
                db = new DatabaseHelper(aContext);

                // bring variable id, to POS interface
                Intent intent = new Intent(aContext, MainActivity.class);
                intent.putExtra("category_id", category_id);
                v.getContext().startActivity(intent);
            }
        });

Answer 1

It is simple. Pass the values from your Activity to the Adapter using the adapter's constructor. This is what the constructors are for.

Like in your activity,

MyAdapter myAdapter = new MyAdapter(variable1, variable2);

Now in your adapter,

private int variable1, variable2;

// Constructor
public MyAdapter(int var1, int var2){
    this.variable1 = var1;
    this.variable2 = var2;
}

You can now easily use these variables in your click listener and pass them to the new intent.

You can also use setters for these variables in the adapter like,

public void setVariable1(int value){
    this.variable1 = value;
}

public void setVariable2(int value){
    this.variable2 = value;
}

And from your activity, do something like this whenever needed,

myAdapter.setVariable1(10);

So, these are the ways for you to access your variables from your activity inside your adapter.