当我想在手机上运行ProjectPlannerPro应用程序时，我遇到了问题。我在Windows 7 - 64位中使用Android Studio 3.0。
问题在于，当我尝试在手机中运行应用程序（三星Galaxy S6 Edge Plus，Android版本7.0，API 24）时，它会崩溃。
这是运行后的logcat：
10-31 22:52:30.773 22504-22504/? E/Zygote: v2
10-31 22:52:30.773 22504-22504/? I/libpersona: KNOX_SDCARD checking this for 10406
10-31 22:52:30.773 22504-22504/? I/libpersona: KNOX_SDCARD not a persona
10-31 22:52:30.774 22504-22504/? E/Zygote: accessInfo : 0
10-31 22:52:30.774 22504-22504/? W/SELinux: SELinux selinux_android_compute_policy_index : Policy Index[2], Con:u:r:zygote:s0 RAM:SEPF_SECMOBILE_7.0_0009, [-1 -1 -4 -1 0 1]
10-31 22:52:30.775 22504-22504/? I/SELinux: SELinux: seapp_context_lookup: seinfo=untrusted, level=s0:c512,c768, pkgname=com.planner.reemshams.projectplannerpro
10-31 22:52:30.777 22504-22504/? I/art: Late-enabling -Xcheck:jni
10-31 22:52:30.792 22504-22504/? D/TimaKeyStoreProvider: TimaKeyStore is not enabled: cannot add TimaSignature Service and generateKeyPair Service
10-31 22:52:30.827 22504-22504/? W/System: ClassLoader referenced unknown path: /data/app/com.planner.reemshams.projectplannerpro-2/lib/arm64
10-31 22:52:30.858 22504-22504/com.planner.reemshams.projectplannerpro D/AndroidRuntime: Shutting down VM
10-31 22:52:30.859 22504-22504/com.planner.reemshams.projectplannerpro E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.planner.reemshams.projectplannerpro, PID: 22504
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.planner.reemshams.projectplannerpro/com.planner.reemshams.projectplannerpro.Register}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2819)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2988)
at android.app.ActivityThread.-wrap14(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1631)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6682)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:117)
at android.support.v7.app.AppCompatDelegateImplV9.<init>(AppCompatDelegateImplV9.java:149)
at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:29)
at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:54)
at android.support.v7.app.AppCompatDelegateImplV23.<init>(AppCompatDelegateImplV23.java:31)
at android.support.v7.app.AppCompatDelegateImplN.<init>(AppCompatDelegateImplN.java:31)
at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:198)
at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183)
at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:519)
at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:190)
at com.planner.reemshams.projectplannerpro.Register.<init>(Register.java:12)
at java.lang.Class.newInstance(Native Method)
at android.app.Instrumentation.newActivity(Instrumentation.java:1086)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2809)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2988)
at android.app.ActivityThread.-wrap14(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1631)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6682)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)
这是我的AndroidManifest.xml文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.planner.reemshams.projectplannerpro">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="Projects List"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity
android:name=".Register"
android:label="Register">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".LoginActivity"
android:label="Login">
<intent-filter>
<action android:name="com.planner.reemshams.projectplannerpro.LoginActivity" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity
android:name=".ProjectsList"
android:label="Projects List">
<intent-filter>
<action android:name="com.planner.reemshams.projectplannerpro.ProjectsList" /> <!-- Change the name to the context activity_projects_list.xml -->
<category android:name="android.intent.category.DEFAULT" /> <!-- Change .LAUNCHER to .DEFAULT, since there should be only one launcher activity -->
</intent-filter>
</activity>
</application>
</manifest>
请帮我解决这个问题。谢谢！
PS： Instant Run已停用。即使启用了相同的错误
更新：以下是Register.java代码：
package com.planner.reemshams.projectplannerpro;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class Register extends AppCompatActivity {
//private EditText email_id = (EditText) findViewById(R.id.email_id);
//private EditText password = (EditText) findViewById(R.id.password);
@Override
protected void onCreate(Bundle savedInstanceState) {
Button register_btn = (Button) findViewById(R.id.register_btn);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_register);
register_btn.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View view){
// Start NewActivity.class
Intent myIntent = new Intent(Register.this,
ProjectsList.class);
startActivity(myIntent);
}
}
);
}
}