java - 不幸的是，项目已在 android studio 中停止

Question

这个问题已经有答案了:

Unfortunately MyApp has stopped. How can I solve this? (23 个回答)

已关闭 3 年前。

该代码的全部内容是在第一个 Activity 中将星座作为输入，单击“确定”后将导航到下一个 Activity ，在下一个 Activity 中将详细信息显示为该特定星座的 Web View 。当我尝试在模拟器或手机中运行代码时，我会收到警告项目正在不断停止并且应用程序关闭。

MainActivity.java

  package com.example.project;

  import androidx.appcompat.app.AppCompatActivity;

  import android.content.Intent;
  import android.os.Bundle;
  import android.text.Editable;
  import android.view.View;
  import android.webkit.WebView;
  import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

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

}
public void send(View v){
    Intent goToSecond = new Intent();
    goToSecond.setClass(this, SecondActivity.class);
    startActivity(goToSecond);
    String sign = ((EditText)(findViewById(R.id.editText_sign))).getText().toString();
    goToSecond.putExtra("sign", sign);
    startActivity(goToSecond);
}
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:orientation="vertical"
android:weightSum="100"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:paddingTop="16dp"
tools:context=".MainActivity"
tools:ignore="Autofill"
android:background="@drawable/signwheel2">


<TextView
    android:id="@+id/textView"
    android:layout_width="56dp"
    android:layout_height="wrap_content"
    android:layout_marginStart="55dp"
    android:background="#EFE9E9"
    android:text="@string/zodiac" />

<EditText
    android:id="@+id/editText_sign"
    android:layout_width="223dp"
    android:layout_height="wrap_content"
    android:layout_marginTop="16dp"
    android:layout_marginBottom="16dp"
    android:background="#FDFCFC"
    android:ems="10"
    android:hint="@string/libra"
    android:inputType="textPersonName" />

<Button
    android:id="@+id/button2"
    android:layout_width="127dp"
    android:layout_height="wrap_content"
    android:onClick="send"
    android:text="@android:string/ok"
    android:visibility="visible" />
</LinearLayout>

SecondActivity.java

package com.example.project;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.webkit.WebView;
import android.widget.Toast;

public class SecondActivity extends AppCompatActivity {

WebView webView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    webView = findViewById(R.id.webview);
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);
    Intent caller = getIntent();
    String sign = caller.getStringExtra("sign");
    assert sign != null;
    switch (sign) {
        case "Taurus":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/taurus-zodiac-sign/");
            break;
        case "Aries":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/aries-zodiac-sign/");
            break;
        case "Leo":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/leo-zodiac-sign/");
            break;
        case "Pisces":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/pisces-zodiac-sign/");
            break;
        case "Scoripo":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/scorpio-zodiac-sign/");
            break;
        case "Sagittarius":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/sagittarius-zodiac-sign/");
            break;
        case "Gemini":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/gemini-zodiac-sign/");
            break;
        case "Virgo":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/virgo-zodiac-sign/");
            break;
        case "Libra":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/libra-zodiac-sign/");
            break;
        case "Capricorn":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/capricorn-zodiac-sign/");
            break;
        case "Aquarius":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/aquarius-zodiac-sign/");
            break;
        case "Cancer":
            webView.loadUrl("https://www.chatelaine.com/living/horoscopes/cancer-zodiac-sign/");
            break;
        default:
            String message1 = "Please check the spelling";
            Toast.makeText(getApplicationContext(), message1, Toast.LENGTH_LONG).show();
            break;
    }

}
}

activity_second.xml

<?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=".SecondActivity">

<WebView
    android:id="@+id/webview"
    android:layout_width="409dp"
    android:layout_height="729dp"
    android:layout_marginStart="1dp"
    android:layout_marginLeft="1dp"
    android:layout_marginTop="1dp"
    android:layout_marginEnd="1dp"
    android:layout_marginRight="1dp"
    android:layout_marginBottom="1dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.project">

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".SecondActivity"></activity>
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

</manifest>

日志猫:

04-22 14:59:17.888 3355-3355/? I/art: Not late-enabling -Xcheck:jni (already on)
04-22 14:59:18.026 3355-3355/com.example.project W/System: ClassLoader referenced unknown path: 
/data/app/com.example.project-2/lib/x86
04-22 14:59:18.045 3355-3355/com.example.project D/AndroidRuntime: Shutting down VM
04-22 14:59:18.046 3355-3355/com.example.project E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.project, PID: 3355
java.lang.RuntimeException: Unable to get provider com.google.android.gms.ads.MobileAdsInitProvider: 
java.lang.IllegalStateException: 

******************************************************************************
* The Google Mobile Ads SDK was initialized incorrectly. AdMob publishers    *
* should follow the instructions here:                                       *
* https://googlemobileadssdk.page.link/admob-android-update-manifest         *
* to add a valid App ID inside the AndroidManifest.                          *
* Google Ad Manager publishers should follow instructions here:              *
* https://googlemobileadssdk.page.link/ad-manager-android-update-manifest.   *
******************************************************************************


    at android.app.ActivityThread.installProvider(ActivityThread.java:5156)
    at android.app.ActivityThread.installContentProviders(ActivityThread.java:4748)
    at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4688)
    at android.app.ActivityThread.-wrap1(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1405)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
 Caused by: java.lang.IllegalStateException: 

******************************************************************************
* The Google Mobile Ads SDK was initialized incorrectly. AdMob publishers    *
* should follow the instructions here:                                       *
* https://googlemobileadssdk.page.link/admob-android-update-manifest         *
* to add a valid App ID inside the AndroidManifest.                          *
* Google Ad Manager publishers should follow instructions here:              *
* https://googlemobileadssdk.page.link/ad-manager-android-update-manifest.   *
******************************************************************************


    at com.google.android.gms.internal.ads.zzyc.attachInfo(com.google.android.gms:play-services-ads- 
    lite@@19.1.0:33)
    at com.google.android.gms.ads.MobileAdsInitProvider.attachInfo(com.google.android.gms:play- 
    services-ads-lite@@19.1.0:3)
    at android.app.ActivityThread.installProvider(ActivityThread.java:5153)
        ... 10 more
    04-22 14:59:20.745 3355-3355/? I/Process: Sending signal. PID: 3355 SIG: 9

Answer 1

您调用了 startActivity 两次，也不需要 .setClass:

   public void send(View v){
     String sign = ((EditText)(findViewById(R.id.editText_sign))).getText().toString();
        Intent goToSecond = new Intent(this, SecondActivity.class);
        //startActivity(goToSecond);//Comment this line
        goToSecond.putExtra("sign", sign);
       startActivity(goToSecond);
}

在 secondactivity 中，您在 setContentView 之前执行 findViewById，在 SecondActivity 中的 setContentView 之后添加以下行

webView = findViewById(R.id.webview);

您的异常表明存在空指针异常，因此请在代码中添加空检查:

String sign = "";
if (getIntent != null){
Intent caller = getIntent();
String sign = caller.getStringExtra("sign");
}

希望这有帮助