我有一个自定义列表适配器，我想将此列表适配器中的值传递给设置适配器的活动。
这是我的适配器代码。
public class RoleList extends ArrayAdapter<String>
{
private ArrayList<String> name;
private ArrayList<String> username;
private ArrayList<String> password;
private ArrayList<String> role;
private Activity context;
private MyActionCallback callback;
public RoleList(Activity context, ArrayList<String> name, ArrayList<String> username, ArrayList<String> password, ArrayList<String> role, MyActionCallback callback)
{
super(context, R.layout.role_list,name);
this.context = context;
this.name = name;
this.username =username;
this.password = password;
this.role = role;
this.callback = callback;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent)
{
LayoutInflater inflater = context.getLayoutInflater();
final View listViewItem = inflater.inflate(R.layout.role_list, null, true);
final TextView textViewName = (TextView) listViewItem.findViewById(R.id.tv_empname);
final TextView textViewusername = (TextView) listViewItem.findViewById(R.id.tv_empusername);
final TextView textViewPass = (TextView) listViewItem.findViewById(R.id.tv_emppassword);
final TextView textViewRole = (TextView) listViewItem.findViewById(R.id.tv_emprole);
Button edit = (Button) listViewItem.findViewById(R.id.btn_editRole);
Button delete = (Button) listViewItem.findViewById(R.id.btn_delRole);
delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
name.remove(position);
username.remove(position);
password.remove(position);
role.remove(position);
callback.onActionPerformed(position);
notifyDataSetChanged();
}
});
edit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
Log.d("Emp Info", name.get(position) + " " + username.get(position) + " " + password.get(position) + " " + role.get(position));
final Dialog dialog = new Dialog(getContext());
dialog.setContentView(R.layout.userreg);
dialog.setTitle("Edit Employee " + name.get(position) + " details");
final String[] arraySpinner = new String[]{"Manager","Stockist","Cashier","Accountant"};
dialog.setCancelable(false);
dialog.setCanceledOnTouchOutside(false);
final EditText emp_name = (EditText) dialog.findViewById(R.id.editTextName);
final EditText emp_uname = (EditText) dialog.findViewById(R.id.editTextUserName);
final EditText emp_pw = (EditText) dialog.findViewById(R.id.editTextPassword);
final Spinner emp_role = (Spinner) dialog.findViewById(R.id.spinner_role);
final TextView textRole = (TextView) dialog.findViewById(R.id.tv_selected_role);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getContext(),android.R.layout.simple_spinner_item, arraySpinner);
emp_role.setAdapter(adapter);
emp_role.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(getContext(), "Role Selected is " + arraySpinner[position], Toast.LENGTH_SHORT).show();
String employee_role = arraySpinner[position];
textRole.setText(employee_role);
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
emp_name.setText(name.get(position));
emp_uname.setText(username.get(position));
emp_pw.setText(password.get(position));
emp_role.setSelection(position);
Button buttoncancel = (Button) dialog.findViewById(R.id.buttonCancel);
buttoncancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
dialog.dismiss();
}
});
Button buttonChange = (Button) dialog.findViewById(R.id.buttonRegister);
buttonChange.setText("Change");
buttonChange.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
textViewName.setText(emp_name.getText().toString());
textViewusername.setText(emp_uname.getText().toString());
textViewPass.setText(emp_pw.getText().toString());
textViewRole.setText(textRole.getText());
dialog.dismiss();
}
});
dialog.show();
}
});
textViewName.setText(name.get(position));
textViewusername.setText(username.get(position));
textViewPass.setText(password.get(position));
textViewRole.setText(role.get(position));
return listViewItem;
}
public interface MyActionCallback{
void onActionPerformed(int position);
}
}
记录Null指针异常。
04-23 14：59：16.462 24919-24919 / org.bordetuts.com.goldmine
E / Android运行时：致命异常：主要04-23 14：59：16.462
24919-24919 / org.bordetuts.com.goldmine E / AndroidRuntime：流程：
org.bordetuts.com.goldmine，PID：24919 04-23 14：59：16.462
24919-24919 / org.bordetuts.com.goldmine E / Android运行时：
java.lang.NullPointerException 04-23 14：59：16.462
24919-24919 / org.bordetuts.com.goldmine E / AndroidRuntime：at
org.bordetuts.com.goldmine.adapter.RoleList $ 1.onClick（RoleList.java:67）
04-23 14：59：16.462 24919-24919 / org.bordetuts.com.goldmine
E / AndroidRuntime：位于
android.view.View.performClick（View.java:4444）04-23 14：59：16.462
24919-24919 / org.bordetuts.com.goldmine E / AndroidRuntime：at
android.view.View $ PerformClick.run（View.java:18440）04-23 14：59：16.462
24919-24919 / org.bordetuts.com.goldmine E / AndroidRuntime：at
android.os.Handler.handleCallback（Handler.java:733）04-23 14：59：16.462
24919-24919 / org.bordetuts.com.goldmine E / AndroidRuntime：at
android.os.Handler.dispatchMessage（Handler.java:95）04-23 14：59：16.462
24919-24919 / org.bordetuts.com.goldmine E / AndroidRuntime：at
android.os.Looper.loop（Looper.java:136）04-23 14：59：16.462
24919-24919 / org.bordetuts.com.goldmine E / AndroidRuntime：at
android.app.ActivityThread.main（ActivityThread.java:5028）04-23
14：59：16.462 24919-24919 / org.bordetuts.com.goldmine E / Android运行时：
在java.lang.reflect.Method.invokeNative（本地方法）04-23
14：59：16.462 24919-24919 / org.bordetuts.com.goldmine E / Android运行时：
在java.lang.reflect.Method.invoke（Method.java:515）04-23 14：59：16.462
24919-24919 / org.bordetuts.com.goldmine E / AndroidRuntime：at
com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:788）
04-23 14：59：16.462 24919-24919 / org.bordetuts.com.goldmine
E / AndroidRuntime：位于
com.android.internal.os.ZygoteInit.main（ZygoteInit.java:604）04-23
14：59：16.462 24919-24919 / org.bordetuts.com.goldmine E / Android运行时：
在dalvik.system.NativeStart.main（本机方法）
我想通知活动，内部发生了一些变化
适配器。例如按下删除键到某个位置。任何
建议，帮助或指示会有所帮助。谢谢。
最佳答案
您的活动：
public class MainActivity extends AppCompatActivity implements YourCustomAdapter.MyActionCallback {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// or something like that
ListView listView = findViewById(R.id.my_list_view);
listView.setAdapter(new YourCustomAdapter(this));
}
@Override
public void onActionPerformed(int position) {
//do here something with your data
}
您的适配器：
public class YourCustomAdapter extends BaseAdapter {
public YourCustomAdapter(
MyActionCallback actionCallback) {
mActionCallback = actionCallback;
}
private MyActionCallback mActionCallback;
@Override
public int getCount() {
return 0;
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// your case specific code
// don't forget to implement view re-using properly,
// don't inflate view each time
delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
name.remove(position);
username.remove(position);
password.remove(position);
role.remove(position);
//pass position of deleted object or any other thing you want
mActionCallback.onActionPerformed(position);
notifyDataSetChanged();
}
});
return null;
}
public interface MyActionCallback{
void onActionPerformed(int position);
}
您还可以使用事件总线（例如Otto），但是我认为对于您的情况而言，仅自定义回调就足够了。这取决于。