java.lang.IllegalStateException应用程序崩溃马上

Question

这里是我的MainActivity.java类：

package com.example.roman.realestatecalculator; 

import android.content.Intent; 
import android.support.design.widget.TextInputEditText; 
import android.support.v4.widget.DrawerLayout; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.CheckBox; 
import android.widget.GridView; 

public class MainActivity extends AppCompatActivity { 


Button propertyVet; 
CheckBox dontKnow; 

Button currentProperties; 

DrawerLayout mDrawerLayout; 
GridView mAppsGrid; 


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


    dontKnow = (CheckBox) findViewById(R.id.dontKnow); 

    propertyVet = (Button) findViewById(R.id.propertyVet); 
      propertyVet.setOnClickListener(new View.OnClickListener() { 
       @Override 
       public void onClick(View v) { 
        Intent calc = new Intent(getApplicationContext(),  Calculator.class); 
        startActivity(calc); 
       } 
      }); 

} 


} 

错误消息是在这里：

06-28 10:47:30.811 32734-32734/com.roman.realestatecalculator E/AndroidRuntime: FATAL EXCEPTION: main 
Process: com.roman.realestatecalculator, PID: 32734 
java.lang.RuntimeException: Unable to start activity 
ComponentInfo{com.roman.realestatecalculator/com.example.roman.realestatecalculator.MainActivity}: 
java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity. 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3254) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350) 
at android.app.ActivityThread.access$1100(ActivityThread.java:222) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:158) 
at android.app.ActivityThread.main(ActivityThread.java:7229) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) 
Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity. 
at android.support.v7.app.AppCompatDelegateImplV7.createSubDecor(AppCompatDelegateImplV7.java:340) 
at android.support.v7.app.AppCompatDelegateImplV7.ensureSubDecor(AppCompatDelegateImplV7.java:309) 
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:273) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:136) 
at com.example.roman.realestatecalculator.MainActivity.onCreate(MainActivity.java:32) 
at android.app.Activity.performCreate(Activity.java:6876) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1135) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3207) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350)  
at android.app.ActivityThread.access$1100(ActivityThread.java:222)  
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795)  
at android.os.Handler.dispatchMessage(Handler.java:102)  
at android.os.Looper.loop(Looper.java:158)  
at android.app.ActivityThread.main(ActivityThread.java:7229)  
at java.lang.reflect.Method.invoke(Native Method)  
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)  
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)  

这是说，错误是在第32行这是在这里：

setContentView(R.layout.activity_main); 

但这似乎不大可能，因为我已粘贴此MainActivity类与xml文件进入不同的项目，一切正常。

我从this，this，并that

试图排在前几位的答案，但没有一个答案工作。

任何帮助将不胜感激！

哦，这里是清单文件：

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

<application 
    android:allowBackup="true" 
    android:icon="@mipmap/ic_launcher" 
    android:label="@string/app_name" 
    android:supportsRtl="true" 
    android:versionCode="3" 
    android:versionName="1.3"> 
    android:theme="@style/AppTheme"> 
    <activity android:name=".MainActivity"> 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

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

</manifest> 

Answer 1

问题是在错误信息完全描述：

您需要使用Theme.AppCompat主题（或后代）与这 活动。

由于您的MainActivity是AppCompatActivity，你需要确保你使用的是一个Theme.AppCompat主题为Activity。

例如：

<activity android:name=".MainActivity" 
    android:theme="@style/Theme.AppCompat.Light"> 
    <intent-filter> 
     <action android:name="android.intent.action.MAIN" /> 

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

，或者根据您想支持的最低API级别，你可以只让MainActivity扩展Activity，而不是AppCompatActivity：

public class MainActivity extends Activity { 
    // ... 
}