java - 错误原因:java.lang.ClassCastException: androidx.viewpager2.widget.ViewPager2 无法转换为 androidx.viewpager.widget.ViewPager
问题描述
我正在构建一个城市指南应用程序,我使用 viewpager2 左右滑动页面。在我添加下面给出的这段代码之前,它一直运行为 0 错误。并得到一个错误说 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sahiladhav.cityguide.Common.OnBoarding}: java.lang.ClassCastException: androidx.viewpager2.widget.ViewPager2 cannot be cast到 androidx.viewpager.widget.ViewPager。
我应该怎么办??
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Common.OnBoarding"
android:padding="20dp">
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/slider"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="@+id/relativelayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent ">
</androidx.viewpager2.widget.ViewPager2>
<RelativeLayout
android:id="@+id/relativelayout"
android:layout_width="match_parent"
android:layout_height="150dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<Button
android:id="@+id/get_started_btn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/let_get_started"
android:background="@color/colorPrimary"/>
<LinearLayout
android:id="@+id/dots"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:padding="20dp"
android:orientation="horizontal" />
<Button
android:id="@+id/next_btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:paddingBottom="20dp"
android:background="#00000000"
android:drawableEnd="@drawable/next_btn"
android:drawableRight="@drawable/next_btn" />
</RelativeLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
我的 JAVA 代码
package com.sahiladhav.cityguide.Common;
import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;
import androidx.viewpager2.widget.ViewPager2;
import android.os.Bundle;
import android.text.Html;
import android.transition.Slide;
import android.widget.LinearLayout;
import android.widget.TextView;
import com.sahiladhav.cityguide.HelperClasses.SliderAdapter;
import com.sahiladhav.cityguide.R;
public class OnBoarding extends AppCompatActivity {
ViewPager viewPager;
LinearLayout dotsLayout;
SliderAdapter sliderAdapter;
TextView[] dots;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_on_boarding);
//Hooks
viewPager = findViewById(R.id.slider);
dotsLayout = findViewById(R.id.dots);
//Call adapter
sliderAdapter = new SliderAdapter(this);
viewPager.setAdapter(sliderAdapter);
addDots();
}
private void addDots(){
dots = new TextView[4];
for (int i=0; i<dots.length; i++){
dots[i] = new TextView(this);
dots[i].setText(Html.fromHtml("•"));
dots[i].setTextSize(35);
dotsLayout.addView(dots[i]);
}
}
}
我得到的日志,我该如何解决这个错误,在解决这个问题之前我无法进一步移动代码......请有人帮助我:((
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.sahiladhav.cityguide, PID: 10535
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sahiladhav.cityguide/com.sahiladhav.cityguide.Common.OnBoarding}: java.lang.ClassCastException: androidx.viewpager2.widget.ViewPager2 cannot be cast to androidx.viewpager.widget.ViewPager
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.ClassCastException: androidx.viewpager2.widget.ViewPager2 cannot be cast to androidx.viewpager.widget.ViewPager
at com.sahiladhav.cityguide.Common.OnBoarding.onCreate(OnBoarding.java:30)
at android.app.Activity.performCreate(Activity.java:8000)
at android.app.Activity.performCreate(Activity.java:7984)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
解决方案
您Viewpager2
在 xml 中使用并在 activty 中导入和声明Viewpager
(这是错误的)
public class OnBoarding extends AppCompatActivity {
ViewPager2 viewPager; //change here
LinearLayout dotsLayou
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