我遇到了一个问题，我试图在我的主要活动中调用一个方法，该方法将我的数据保存到按钮上的数据库中点击我的片段。问题是我不确定该方法括号中的内容。
这是我的主要活动类
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
NavigationView navigationView = null;
Toolbar toolbar = null;
DatabaseHelper myDB;
EditText tNumber, tPoticullis, tChevalFrise, tMoat, tRamparts, tDrawbridge, tSallyPort, tRockWall, tRockTerrain, tLowBar;
Context context = this;
DatabaseHelper databaseHelper;
SQLiteDatabase sqLiteDatabase;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Create database
myDB = new DatabaseHelper(this);
//Instantiate all editText objects
tNumber = (EditText) findViewById(R.id.editNumber);
tPoticullis = (EditText) findViewById(R.id.editPoticullis);
tChevalFrise = (EditText) findViewById(R.id.editChevalFrise);
tMoat = (EditText) findViewById(R.id.editMoat);
tRamparts = (EditText) findViewById(R.id.editRamparts);
tDrawbridge = (EditText) findViewById(R.id.editDrawbridge);
tSallyPort = (EditText) findViewById(R.id.editSallyPort);
tRockWall = (EditText) findViewById(R.id.editRockWall);
tRockTerrain = (EditText) findViewById(R.id.editRockTerrain);
tLowBar = (EditText) findViewById(R.id.editLowBar);
//Set the fragment initially
WelcomeFragment fragment = new WelcomeFragment();
android.support.v4.app.FragmentTransaction fragmentTransaction =
getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment);
fragmentTransaction.commit();
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
navigationView = (NavigationView) findViewById(R.id.nav_view);
//How to change elements in the header programatically
View headerView = navigationView.getHeaderView(0);
TextView emailText = (TextView) headerView.findViewById(R.id.description);
emailText.setText("Scouting Application");
navigationView.setNavigationItemSelectedListener(this);
} //End of onCreate
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
} //End of if statement
} //End of onBackPressed
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
} //End of onCreateOptionsMenu
@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;
} //End of if statement
return super.onOptionsItemSelected(item);
} //End of onOptionsItemSelected
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_welcome) {
//Set the fragment initially
WelcomeFragment fragment = new WelcomeFragment();
android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment);
fragmentTransaction.commit();
// Handle the camera action
}
else if (id == R.id.nav_facebook) {
FacebookFragment fragment = new FacebookFragment();
android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment);
fragmentTransaction.commit();
}
else if (id == R.id.nav_members) {
//Set the fragment initially
MembersFragment fragment = new MembersFragment();
android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment);
fragmentTransaction.commit();
}
else if (id == R.id.nav_robot) {
}
else if (id == R.id.nav_scout) {
//Set the fragment initially
ScoutFragment fragment = new ScoutFragment();
android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment);
fragmentTransaction.commit();
}
else if (id == R.id.nav_match) {
//Set the fragment initially
MatchFragment fragment = new MatchFragment();
android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment);
fragmentTransaction.commit();
} //End of if statement
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
} //End of onNavigationItemSelected
public void addScoutInfo(View view){
//Converts all editText values into strings
String sNumber = tNumber.getText().toString();
String sPoticullis = tPoticullis.getText().toString();
String sChevalFrise = tChevalFrise.getText().toString();
String sMoat = tMoat.getText().toString();
String sRamparts = tRamparts.getText().toString();
String sDrawbridge = tDrawbridge.getText().toString();
String sSallyPort = tSallyPort.getText().toString();
String sRockWall = tRockWall.getText().toString();
String sRockTerrain = tRockTerrain.getText().toString();
String sLowBar = tLowBar.getText().toString();
//Saves data
databaseHelper = new DatabaseHelper(context);
sqLiteDatabase = databaseHelper.getWritableDatabase();
databaseHelper.addInformation(sNumber, sPoticullis, sChevalFrise, sMoat, sRamparts, sDrawbridge, sSallyPort, sRockWall,
sRockTerrain, sLowBar, sqLiteDatabase);
Toast.makeText(getBaseContext(), "Data Saved", Toast.LENGTH_LONG).show();
databaseHelper.close();
} //End of addScoutInfo
} //End of class
这是我的片段类
import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
/**
* A simple {@link Fragment} subclass.
*/
public class AddScoutDataFragment extends Fragment {
Button cancelButton;
Button addDataButton;
public AddScoutDataFragment() {
// Required empty public constructor
} //End of AddScoutDataFragment
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
final View view = inflater.inflate(R.layout.fragment_add_scout_data, container, false);
view.setBackgroundColor(Color.WHITE);
//Adds data to ScoutFragment
addDataButton = (Button) view.findViewById(R.id.buttonDataAdd);
addDataButton.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
//Saves data to database
MainActivity mainActivity = ((MainActivity)getActivity()).addScoutInfo();
//Returns to ScoutFragment
ScoutFragment fragment = new ScoutFragment();
FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
fragmentTransaction.setCustomAnimations(R.anim.enter_from_left, R.anim.exit_to_right, R.anim.enter_from_right, R.anim.exit_to_left);
fragmentTransaction.replace(R.id.fragment_container, fragment);
fragmentTransaction.commit();
} //End of onClick
}); //End of setOnClickListener
//Returns to ScoutFragment without adding any data
cancelButton = (Button) view.findViewById(R.id.buttonCancel);
cancelButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
//Returns to ScoutFragment
ScoutFragment fragment = new ScoutFragment();
FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
fragmentTransaction.setCustomAnimations(R.anim.enter_from_left, R.anim.exit_to_right, R.anim.enter_from_right, R.anim.exit_to_left);
fragmentTransaction.replace(R.id.fragment_container, fragment);
fragmentTransaction.commit();
} //End of onClick
}); //End of setOnClickListener
// Inflates the layout for this fragment
return view;
} //End of onCreateView
} //End of class
问题发生在onCreateView方法MainActivity mainActivity = ((MainActivity)getActivity()).addScoutInfo(Need to insert something here);
答案 0 :(得分：1)
addScoutInfo函数参数未在该函数中使用，因此您只需传递null或删除参数即可。这将使您的代码工作但将getActivity()的结果强制转换为特定类型通常是错误的想法。该片段将来可以被其他活动重用，并且该演员阵容将不再有效。
以下是一些可以改进代码的建议：
答案 1 :(得分：0)
在片段中，在onbind（）方法中，添加侦听器并在Main Activity类中实现它，这样就可以将此方法从片段调用到activity。更多信息：
http://developer.android.com/training/basics/fragments/communicating.html
答案 2 :(得分：-1)
如果你没有在XML中的小部件中使用 android：onClick =＆＃34; addScoutInfo＆＃34; 方法，你可以删除你的参数addScoutInfo方法。否则，您必须传递已触发的视图，例如您的btn_add_scout_info按钮。