如何解决？当我点击按钮时，我的应用程序正在关闭

Question

public class Navigationmenu extends AppCompatActivity { 
     private DrawerLayout mDrawerLayout; 
     private ActionBarDrawerToggle mToggle; 
     private Toolbar mToolbar; 
     @Override 
     protected void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.activity_navigationmenu); 

      mDrawerLayout = (DrawerLayout)findViewById(R.id.drawerLayout); 
      mToggle = new ActionBarDrawerToggle(this,mDrawerLayout,R.string.Open,R.string.Close); 

      mToolbar = (Toolbar)findViewById(R.id.nav_action); 
      setSupportActionBar(mToolbar); 

      mDrawerLayout.addDrawerListener(mToggle); 
      mToggle.syncState(); 

      getSupportActionBar().setDisplayHomeAsUpEnabled(true); 
     } 



     @Override 
     public boolean onOptionsItemSelected(MenuItem item) { 
      if(mToggle.onOptionsItemSelected(item)) 
      { 
       return true; 
      } 
      return super.onOptionsItemSelected(item); 
     } 
    } 

错误。

我该如何解决？当我点击按钮时，我的应用程序被迫关闭。任何人都可以帮助我吗？

错误显示在“super.onCreate(savedInstanceState);”我不知道如何解决它。

Answer 1

我无法确定您的照片，但似乎您正尝试将导航抽屉添加到您的项目中。您无法在预先存在的代码之上添加导航抽屉，相反，这样做会更麻烦。

为了让导航抽屉工作，您必须添加一些其他代码，而不是Android Studio提供的代码。如果要添加导航抽屉而不是需要将代码添加到MainActivity.java而不是其自己的文件，然后可以在每个其他片段类中实现该抽屉，以使导航抽屉工作。

什么你可以尝试添加是一样的东西

public class Navigationmenu extends AppCompatActivity { 
    //Try this piece here 
    NavigationView navigationView = null; 
    private DrawerLayout mDrawerLayout; 
    private ActionBarDrawerToggle mToggle; 
    private Toolbar mToolbar; 

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

     mDrawerLayout = (DrawerLayout)findViewById(R.id.drawerLayout); 
     mToggle = new ActionBarDrawerToggle(this,mDrawerLayout,R.string.Open,R.string.Close); 

     mToolbar = (Toolbar)findViewById(R.id.nav_action); 
     setSupportActionBar(mToolbar); 

     mDrawerLayout.addDrawerListener(mToggle); 
     mToggle.syncState(); 


     //Try adding this to the code 
     navigationView = (NavigationView) findViewById(R.id.nav_view); //Declared in activity_main.xml 
     navigationView.setNavigationItemSelectedListener(this); 

     getSupportActionBar().setDisplayHomeAsUpEnabled(true); 
    } 



    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     if(mToggle.onOptionsItemSelected(item)) 
     { 
      return true; 
     } 
     return super.onOptionsItemSelected(item); 
    } 
} 

如果你正试图使抽屉式导航与片段，看向我提出这个完整MainActivity.java，并注意在导航抽屉，一切运行在片段上。

import android.net.Uri; 
import android.os.Bundle; 
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; 

public class MainActivity extends AppCompatActivity 
     implements NavigationView.OnNavigationItemSelectedListener, MainFragment.OnFragmentInteractionListener, LoginFragment.OnFragmentInteractionListener { 



    NavigationView navigationView = null; 
    Toolbar toolbar = null; 

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


     toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 


     MainFragment fragment = new MainFragment(); 

     android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 

     fragmentTransaction.replace(R.id.fragment_container, fragment); 
     fragmentTransaction.commit(); 



     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); 
     navigationView.setNavigationItemSelectedListener(this); 
    } 

    @Override 
    public void onBackPressed() { 
     DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
     if (drawer.isDrawerOpen(GravityCompat.START)) { 
      drawer.closeDrawer(GravityCompat.START); 
     } else { 
      super.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; 
    } 

    @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); 
    } 

    @SuppressWarnings("StatementWithEmptyBody") 
    @Override 
    public boolean onNavigationItemSelected(MenuItem item) { 
     // Handle navigation view item clicks here. 
     int id = item.getItemId(); 

     if (id == R.id.main) { 
      MainFragment fragment = new MainFragment(); 
      android.support.v4.app.FragmentTransaction fragmentTransaction = 
        getSupportFragmentManager().beginTransaction(); 
      fragmentTransaction.replace(R.id.fragment_container, fragment); 
      fragmentTransaction.commit(); 

     } else if (id == R.id.login) { 
      LoginFragment fragment = new LoginFragment(); 
      android.support.v4.app.FragmentTransaction fragmentTransaction = 
        getSupportFragmentManager().beginTransaction(); 
      fragmentTransaction.replace(R.id.fragment_container, fragment); 
      fragmentTransaction.commit(); 

     } else if (id == R.id.nav_slideshow) { 

     } else if (id == R.id.nav_manage) { 

     } else if (id == R.id.nav_share) { 

     } else if (id == R.id.nav_send) { 

     } 

     DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
     drawer.closeDrawer(GravityCompat.START); 
     return true; 
    } 

    @Override 
    public void onFragmentInteraction(Uri uri) { 
     //Leave blank 
    } 
}