【发布时间】：2016-12-08 06:48:54
【问题描述】：
我正在尝试使用接口从适配器类调用活动方法。两个活动都是独立的，即调用适配器的类和定义方法的类。
接口类
public interface AdapterCallback {
int onMethodCallback();
}
适配器类
public class SimpleAdapter extends RecyclerView.Adapter<SimpleAdapter.ViewHolder> {
String[] goals;
Context context;
private AdapterCallback mAdapterCallback;
public SimpleAdapter(Context context, String[] goals)
{
super();
this.context=context;
this.goals=goals;
}
/* public SimpleAdapter(Context context) {
try {
} catch (ClassCastException e) {
throw new ClassCastException("Activity must implement AdapterCallback.");
}
}*/
@Override
public SimpleAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.simple_item,parent,false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(final SimpleAdapter.ViewHolder holder, int position) {
holder.textView.setText(goals[position]);
holder.textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
try {
mAdapterCallback = ((AdapterCallback) context);
int result=mAdapterCallback.onMethodCallback();
Toast.makeText(context,Integer.toString(result), Toast.LENGTH_SHORT).show();
} catch (ClassCastException exception) {
// do something
Log.i("In the catch","Yes");
}
}
});
}
@Override
public int getItemCount() {
return goals.length;
}
public class ViewHolder extends RecyclerView.ViewHolder {
Button textView;
public ViewHolder(View itemView) {
super(itemView);
textView=(Button) itemView.findViewById(R.id.text);
}
}
}
方法在 MainActivity.class 中定义
@Override
public int onMethodCallback() {
// do something
return 2;
}
问题： 我应该如何调用接口函数，以便间接调用 MainActivity 类中定义的函数。
我知道我需要提供 MainActivity 的上下文
mAdapterCallback = ((AdapterCallback) context);
但是我应该把这段代码放在哪里。
如果我将这段代码放在构造函数中，那么它将不会获得 MainActivity 类上下文，因为适配器是从另一个类调用的。
编辑：
public class MainActivity extends AppCompatActivity implements AdapterCallback {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
@Override
public int onMethodCallback() {
// do something
return 2;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, 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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public int sampleFunction()
{
return 2;
}
}
编辑 2
调用适配器类的类
public class OtherClass extends AppCompatActivity {
RecyclerView recyclerView;
SimpleAdapter simpleAdapter;
String[] action_name={"Swimming","Yoga","SWD","IFT","Follow Diet Plan", "Diagnostic Tests","Record Temperature","Record Blood Pressure"," Record Sugar Level","Record Weight"};
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.xtra);
recyclerView=(RecyclerView) findViewById(R.id.recylerview);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
simpleAdapter=new SimpleAdapter(this, action_name);
recyclerView.setAdapter(simpleAdapter);
}
}
【问题讨论】：
-
能把MainActivity的代码发一下吗？
-
完成@DeepakSachdeva
-
检查我发布的解决方案。
-
更新@DeepakSachdeva
-
@AnkurKhandelwal 试试我的解决方案？如果您有任何问题，请告诉我？
标签： java android interface android-arrayadapter