我试图使用interface调用适配器类中的activity方法。这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);
但我应该把这段代码放在哪里。
如果我将此代码放在构造函数中，那么它将无法获取MainActivity类上下文，因为适配器正在从另一个类调用。
修改
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);
}
}
答案 0 :(得分：0)
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 implements View.OnClickListener {
Button textView;
public ViewHolder(View itemView) {
super(itemView);
textView=(Button) itemView.findViewById(R.id.text);
//for entire cell
itemView.setOnClickListener(this);
//or only for button
textView.setOnClickListener(this);
}
@Override
public void onClick(View view) {
/*
If your want clicked position you can use bellow code
*/
//int clicked_position = getAdapterPosition();
mAdapterCallback.onMethodCallback(clicked_position,goals[clicked_position]);
}
}
}
这是我们在android recyclerview中使用界面的方式
<强>编辑
更改您的界面，如下面的
public interface AdapterCallback {
void onMethodCallback(int position,String value);
}
和你的OtherClass.class一样，如bellow
public class OtherClass extends AppCompatActivity implements AdapterCallback{
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);
}
@Override
public void onMethodCallback(int position, String value) {
System.out.println(value+" "+position);
//start activity intent here , now you have position as well as selected value
}
}
答案 1 :(得分：0)
如果您在MainActivity中实现了接口 AdapterCallback ，则调用SimpleAdapter的构造函数，并包含一个新的AdapterCallback Object参数。尝试这些变化。它可能会帮助你
String[] goals;
Context context;
private AdapterCallback mAdapterCallback;
public SimpleAdapter(Context context, AdapterCallback adapterCallback, String[] goals){
super();
this.context=context;
this.adapterCallback = adapterCallback;
this.goals=goals;
}
并删除此
mAdapterCallback = ((AdapterCallback) context);
答案 2 :(得分：0)
首先设置接口。在适配器类中编写这样的方法
AdapterCallback adapterCallback ;
public void setAdapterCallback(AdapterCallback adapterCallback){
this.adapterCallback = adapterCallback
}
现在实现并初始化您实际需要回调的界面。在你的情况下MainActivity这样做
MainActivity extends AppCompatActivity implements AdapterCallback
现在就像这样初始化你的界面。
SimpleAdapter adpter = new SimpleAdapter()
adpter.setAdapterCallback(this); // very imp step
现在发送像这样的回调
holder.textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(adapterCallback != null){
adapterCallback.onMethodCallback();
}
}
});
所有你将得到你的主要活动的回调..
修改
我看到你在另一个活动中设置了适配器..在这种情况下你必须像这样传递你的接口对象
AdapterCallback adapterCallback = this;
Intent intent = new Intent(context, OtherClass.class);
intent.putExtra("interface", adapterCallback);
startActivity(intent);
在OtherClass中检索它;
Intent intent = getIntent();
AdapterCallback inter = (AdapterCallback) intent.getSerializableExtra("interface");
同时将接口更改为可序列化。
public interface AdapterCallback extends Serializable {
int onMethodCallback();
}
像这样的setInterface
simpleAdapter.setAdapterCallback(inter);
如果你jsut使用了一个片段而不是其他类，那么它会更容易......
修改
如果两个活动都是独立的，那么您可以在Application类中为您的接口编写gettter和setter。从mainActivity设置界面并在adater中获取回调。
在应用程序类
AdapterCallback adapterCallback;
public AdapterCallback getAdapterCallback() {
return adapterCallback;
}
public void setAdapterCallback(AdapterCallback adapterCallback) {
this.adapterCallback = adapterCallback;
}
将此内容写入主要
((YourApplication)getApplication()). setAdapterCallback(this);
在点击中使用此方法
((YourApplication) getApplication()).getAdapterCallback().onMethodCallback();
答案 3 :(得分：0)
我不确定只是尝试一下，
如果您有Util类创建方法或创建Util类并执行
说
private Context mContext;
public void setContext(Context context) {
mContext = context;
}
public Context getContext(){
return mContext;
}
然后
在MainActivity中设置上下文
喜欢
Util.setContext(MainActivity.this);
并在SimpleAdapter类中使用Util.getContext（）和
Context context = Util.getContext();
if(context != null && context instanceof MainActivity){
mAdapterCallback = ((AdapterCallback) context);
int result=mAdapterCallback.onMethodCallback();
}