java - android.widget.RelativeLayout 无法转换为 androidx.drawerlayout.widget.DrawerLayout

Question

最近我添加了“使用 google 登录”按钮并且工作正常，但是现在当我尝试运行该应用程序时弹出此错误，我不知道为什么。

这是完整的异常:

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.miapp, PID: 26644
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.miapp/com.example.loginapp.HomeScreen}: java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to androidx.drawerlayout.widget.DrawerLayout
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3114)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3257)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1948)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7050)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:965)
     Caused by: java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to androidx.drawerlayout.widget.DrawerLayout
        at com.example.loginapp.HomeScreen.onCreate(HomeScreen.java:31)
        at android.app.Activity.performCreate(Activity.java:7327)
        at android.app.Activity.performCreate(Activity.java:7318)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3094)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3257) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1948) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7050) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:965)

错误似乎在这一行:

        dl = findViewById(R.id.dl);

这是 MainActivity(主屏幕 Activity )

package com.example.loginapp;

import androidx.annotation.NonNull;
import androidx.appcompat.app.ActionBarDrawerToggle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.drawerlayout.widget.DrawerLayout;

import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

import com.google.android.material.navigation.NavigationView;
import com.google.firebase.auth.FirebaseAuth;

public class HomeScreen extends AppCompatActivity {

    private FirebaseAuth firebaseAuth;
    private DrawerLayout dl;
    private ActionBarDrawerToggle abdt;


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

        NavigationView nav_view = findViewById(R.id.nav_view);

        dl = findViewById(R.id.dl);
        abdt = new ActionBarDrawerToggle(this, dl,R.string.Open, R.string.Close);
        abdt.setDrawerIndicatorEnabled(true);

        firebaseAuth = FirebaseAuth.getInstance();

        dl.addDrawerListener(abdt);
        abdt.syncState();

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);


        nav_view.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener(){

            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
                int id = menuItem.getItemId();

                if (id == R.id.miPerfil){

                    startActivity(new Intent(HomeScreen.this, MiPerfil.class));
                }

                if (id == R.id.ayudaPerfil){

                    Toast.makeText(HomeScreen.this, "Ayuda", Toast.LENGTH_SHORT).show();
                }

                if (id == R.id.agregarLista){
                    startActivity(new Intent(HomeScreen.this, HomeActivity.class));
                    Toast.makeText(HomeScreen.this, "Añadir actividad", Toast.LENGTH_SHORT).show();
                }

                if (id == R.id.logoutMenu){
                    Toast.makeText(HomeScreen.this, "Cerrando sesión... ", Toast.LENGTH_SHORT).show();
                    Logout();
                }

                return true;
            }
        });

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.navigation_menu, menu);
        return super.onCreateOptionsMenu(menu);
    }


    @Override
    public boolean onOptionsItemSelected(MenuItem item){

        return super.onOptionsItemSelected(item) || abdt.onOptionsItemSelected(item);
    }

    private void Logout(){
        firebaseAuth.signOut();
        finish();
        startActivity(new Intent(HomeScreen.this, MainActivityy.class));
    }
}

这是 XML

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFF"
    android:orientation="vertical"
    android:id="@+id/dl">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#000">

    </RelativeLayout>
    <com.google.android.material.navigation.NavigationView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:id="@+id/nav_view"
        android:layout_gravity="start"
        android:background="#FFF"
        app:headerLayout="@layout/navigation_header"
        app:menu="@menu/navigation_menu">

    </com.google.android.material.navigation.NavigationView>
</RelativeLayout>

拜托，如果你能帮上忙，我将不胜感激。

Answer 1

堆栈跟踪清楚地指出了问题。您正在 xml 中使用 RelativeLayout 并尝试将其转换为 Activity 代码中的 DrawerLayout。在布局 xml 中使用 androidx.drawerlayout.widget.DrawerLayout 而不是 RelativeLayout。

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFF"
    android:fitsSystemWindows="true"
    tools:openDrawer="start"
    android:id="@+id/dl">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#000">

    </RelativeLayout>
    <com.google.android.material.navigation.NavigationView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:id="@+id/nav_view"
        android:layout_gravity="start"
        android:background="#FFF"
        app:headerLayout="@layout/navigation_header"
        app:menu="@menu/navigation_menu">

    </com.google.android.material.navigation.NavigationView>
</androidx.drawerlayout.widget.DrawerLayout>