導航抽屜片段問題

Question

嗨，我的導航抽屜有這個問題。 抽屜可以打開，但是onClickListener出現問題。 如果在抽屜上單擊某個項目，則不會顯示相關的布局，而是會顯示黑頁。 請幫忙

home.java

import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.support.design.widget.NavigationView;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SubMenu;
import android.view.View;
import android.widget.Toast;

public class home extends AppCompatActivity {

    //Defining Variables
    private Toolbar toolbar;
    private NavigationView navigationView;
    private DrawerLayout drawerLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);

        // Initializing Toolbar and setting it as the actionbar
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        //Initializing NavigationView
        navigationView = (NavigationView) findViewById(R.id.navigation_view);

        //Setting Navigation View Item Selected Listener to handle the item click of the navigation menu
        navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {

            // This method will trigger on item Click of navigation menu
            @Override
            public boolean onNavigationItemSelected(MenuItem menuItem) {


                //Checking if the item is in checked state or not, if not make it in checked state
                if(menuItem.isChecked()) menuItem.setChecked(false);
                else menuItem.setChecked(true);

                //Closing drawer on item click
                drawerLayout.closeDrawers();

                //Check to see which item was being clicked and perform appropriate action
                switch (menuItem.getItemId()){


                    //Replacing the main content with ContentFragment Which is our Inbox View;
                    case R.id.dashboard:
                        Toast.makeText(getApplicationContext(),"dashboard",Toast.LENGTH_SHORT).show();
                        Dashboard fragment = new Dashboard();
                        android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
                        fragmentTransaction.replace(R.id.frame,fragment);
                        fragmentTransaction.commit();
                       break;

                    // For rest of the options we just show a toast on click

                    case R.id.profile:
                        Toast.makeText(getApplicationContext(),"profile",Toast.LENGTH_SHORT).show();
                        new Profile();
                        break;
                    case R.id.logs:
                        Toast.makeText(getApplicationContext(),"logs",Toast.LENGTH_SHORT).show();
                        new Logs();
                        break;
                    case R.id.statements:
                        Toast.makeText(getApplicationContext(),"statements",Toast.LENGTH_SHORT).show();
                        new Statements();
                       break;
                    case R.id.timeline:
                        Toast.makeText(getApplicationContext(),"timeliine",Toast.LENGTH_SHORT).show();
                        new Timeline();
                        break;
                    case R.id.settings:
                        Toast.makeText(getApplicationContext(),"settings",Toast.LENGTH_SHORT).show();
                        new Settings();
                        break;

                    default:
                        Toast.makeText(getApplicationContext(),"Somethings Wrong",Toast.LENGTH_SHORT).show();
                        break;

                }
          return true;  }
        });

        // Initializing Drawer Layout and ActionBarToggle
        drawerLayout = (DrawerLayout) findViewById(R.id.drawer);
        ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this,drawerLayout,toolbar,R.string.openDrawer, R.string.closeDrawer){

            @Override
            public void onDrawerClosed(View drawerView) {
                // Code here will be triggered once the drawer closes as we dont want anything to happen so we leave this blank
                super.onDrawerClosed(drawerView);
            }

            @Override
            public void onDrawerOpened(View drawerView) {
                // Code here will be triggered once the drawer open as we dont want anything to happen so we leave this blank

                super.onDrawerOpened(drawerView);
            }
        };

        //Setting the actionbarToggle to drawer layout
        drawerLayout.setDrawerListener(actionBarDrawerToggle);

        //calling sync state is necessay or else your hamburger icon wont show up
        actionBarDrawerToggle.syncState();






    }

    @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);
    }
}

Answer 1

您沒有在case語句中正確切換片段。 您只實例化一個新的Fragment類，而不對它做任何事情。 您需要執行以下操作：

Fragment fragment;
switch (menuItem.getItemId()){


                //Replacing the main content with ContentFragment Which is our Inbox View;
                case R.id.dashboard:
                    Toast.makeText(getApplicationContext(),"dashboard",Toast.LENGTH_SHORT).show();
                    fragment = new Dashboard();
                   break;

                // For rest of the options we just show a toast on click

                case R.id.profile:
                    Toast.makeText(getApplicationContext(),"profile",Toast.LENGTH_SHORT).show();
                    fragment = new Profile();
                    break;
                case R.id.logs:
                    Toast.makeText(getApplicationContext(),"logs",Toast.LENGTH_SHORT).show();
                    fragment = new Logs();
                    break;
                case R.id.statements:
                    Toast.makeText(getApplicationContext(),"statements",Toast.LENGTH_SHORT).show();
                    fragment = new Statements();
                   break;
                case R.id.timeline:
                    Toast.makeText(getApplicationContext(),"timeliine",Toast.LENGTH_SHORT).show();
                    fragment = new Timeline();
                    break;
                case R.id.settings:
                    Toast.makeText(getApplicationContext(),"settings",Toast.LENGTH_SHORT).show();
                    fragment = new Settings();
                    break;

                default:
                    Toast.makeText(getApplicationContext(),"Somethings Wrong",Toast.LENGTH_SHORT).show();
                    break;

            }
android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
                    fragmentTransaction.replace(R.id.frame,fragment);
                    fragmentTransaction.commit();

這樣，您每次都使用適當的Fragment類實例化一個片段，最后，用該特定片段替換幀。

Digresion：建議您使用newInstance而不是構造函數來獲取片段。 這稱為Singleton設計模式。