Question

美好的一天，我的应用程序被迫关闭，我得到这样的日志猫。根据LogCat，我认为问题出在第51行，但我不知道为什么会出错。

第51行的代码为：

bar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#00C4CD")));

MainActivity.java

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

    // c = MainActivity.this;
    ActionBar bar = getActionBar();

    bar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#00C4CD")));

logcat的

11-07 18:25:40.526: E/AndroidRuntime(17342): FATAL EXCEPTION: main
11-07 18:25:40.526: E/AndroidRuntime(17342): Process: com.fyp.atms, PID: 17342
11-07 18:25:40.526: E/AndroidRuntime(17342): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.fyp.atms/com.fyp.atms.MainActivity}: java.lang.NullPointerException
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2198)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2248)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.app.ActivityThread.access$800(ActivityThread.java:138)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1199)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.os.Handler.dispatchMessage(Handler.java:102)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.os.Looper.loop(Looper.java:136)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.app.ActivityThread.main(ActivityThread.java:5050)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at java.lang.reflect.Method.invokeNative(Native Method)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at java.lang.reflect.Method.invoke(Method.java:515)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:805)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:621)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at dalvik.system.NativeStart.main(Native Method)
11-07 18:25:40.526: E/AndroidRuntime(17342): Caused by: java.lang.NullPointerException
11-07 18:25:40.526: E/AndroidRuntime(17342):    at com.fyp.atms.MainActivity.onCreate(MainActivity.java:51)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.app.Activity.performCreate(Activity.java:5242)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-07 18:25:40.526: E/AndroidRuntime(17342):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2162)

试图将此添加到我的值中 - ＆gt; style.xml但仍无效。

<resources>

    <style name="ActionBarTheme" parent="android:Widget.Holo.Light.ActionBar.Solid.Inverse">
    <item name="android:background">#00C4CD</item>
    </style> 



    <style name="AppBaseTheme" parent="Theme.AppCompat.Light">
        <!--
            Theme customizations available in newer API levels can go in
            res/values-vXX/styles.xml, while customizations related to
            backward-compatibility can go here.
        -->
    </style>

    <!-- Application theme. -->
    <style name="AppTheme" parent="android:Theme.Holo.Light.DarkActionBar">
        <item name="android:actionBarStyle">@style/ActionBarTheme</item>
    </style>

</resources>

添加styles.xml后的LogCat

 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.fyp.atms/com.fyp.atms.MainActivity}: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.

Answer 1

我遇到了这个问题，并提出了以下实现，这在我的案例中有用......

在AndroidManifest.xml中，在活动中使用Theme.AppCompat样式。

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name">
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:theme="@style/Theme.AppCompat">
    ...

在MainActivity.java代码中，确保1）导入v7 ActionBarActivity，2）使活动扩展ActionBarActivity，3）使用相应的v7栏和getSupportActionBar()方法

import android.support.v7.app.ActionBarActivity;

...

public class MainActivity extends ActionBarActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        android.support.v7.app.ActionBar bar = getSupportActionBar();
        if(bar != null){
            bar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#3f4deb")));
        }
    }

这基于http://developer.android.com/guide/topics/ui/actionbar.html。我无法使API 11及更高版本的方法起作用，但上述解决方案足以满足我的需求。

Answer 2

尝试添加

getWindow().requestFeature(Window.FEATURE_ACTION_BAR);

在ActionBar bar = getActionBar（）;

之前

Answer 3

试试这个：

bar.setBackgroundColor(Color.parseColor("#00C4CD"));

ActionBar setBackgroundDrawable force close

3 个答案: