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社区首页 >问答首页 >我想实现‘屏幕截图’功能和‘分享’选项在我的Android应用程序，但抛出错误

问我想实现‘屏幕截图’功能和‘分享’选项在我的Android应用程序，但抛出错误
EN

Stack Overflow用户
提问于 2016-09-14 06:54:36
回答 1查看 119关注 0票数 0

我正在构建一个android应用程序，并想在我的Android应用程序中实现‘屏幕截图’功能和‘共享’选项在点击共享按钮。

但在运行时，它会抛出以下错误，并且单击按钮时没有任何反应。请帮帮我！

尝试加载暂存凭据时出错: java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法的java.lang.String

代码如下：

代码语言：javascript
复制
public class ShareActivity extends MainActivity{

Button share;
File imagePath;    

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main); 
    share  = (Button)findViewById(R.id.share1);
    share.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Bitmap bitmap = takeScreenshot();
            saveBitmap(bitmap);
            shareIt();
        }
    });
}

//Screenshot method to take the screenshot in app

public Bitmap takeScreenshot() {

    View rootView = getWindow().getDecorView().findViewById(android.R.id.content);
        //View rootView = findViewById(android.R.id.content).getRootView();
        //rootView.setDrawingCacheEnabled(true);
        //return rootView.getDrawingCache();
        //View screenView = view.getRootView();
    rootView.setDrawingCacheEnabled(true);
    Bitmap bitmap = Bitmap.createBitmap(rootView.getDrawingCache());
    rootView.setDrawingCacheEnabled(false);
    return bitmap;
}

public void saveBitmap(Bitmap bitmap) {
    imagePath = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+ "/screenshot.png");
    FileOutputStream fos;
    try {
        fos = new FileOutputStream(imagePath);
        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
        fos.flush();
        fos.close();
    } catch (FileNotFoundException e) {
        Log.e("GREC", e.getMessage(), e);
    } catch (IOException e) {
        Log.e("GREC", e.getMessage(), e);
    }
}

//ShareIt method to invoke the share the screen shot captured

private void shareIt() {
    Uri uri = Uri.fromFile(imagePath);
    Intent sharingIntent = new Intent(android.content.Intent.ACTION_SEND);
    Intent intent = this.getIntent();
    Bundle bundle= getIntent().getExtras();   
     sharingIntent = intent.setType("image/*");
      //sharingIntent.setType("image/*");
     String shareBody = "In Tweecher, My highest score with screen shot";
     sharingIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, "My Tweecher score");
     sharingIntent.putExtra(android.content.Intent.EXTRA_TEXT, shareBody);
     sharingIntent.putExtra(Intent.EXTRA_STREAM, uri);
     startActivity(Intent.createChooser(sharingIntent, "Share via"));
}
}

堆栈跟踪日志：

代码语言：javascript
复制
09-14 21:25:21.470 2844-2844/com.mycompany.myfirstglapp I/art: Not late-enabling -Xcheck:jni (already on)
09-14 21:25:21.881 2844-2844/com.mycompany.myfirstglapp I/MapboxEventManager: Telemetry initialize() called...
09-14 21:25:21.883 2844-2844/com.mycompany.myfirstglapp I/MapboxEventManager: Right before Telemetry set enabled in initialized()
09-14 21:25:21.888 2844-2844/com.mycompany.myfirstglapp I/MapboxEventManager: setTelemetryEnabled(); this.telemetryEnabled = false; telemetryEnabled = true
09-14 21:25:21.888 2844-2844/com.mycompany.myfirstglapp D/MapboxEventManager: Starting Telemetry Up!
09-14 21:25:21.921 2844-2844/com.mycompany.myfirstglapp I/MapboxEventManager: Permissions are good, see if GPS is enabled and if not then setup Ambient.
09-14 21:25:21.923 2844-2844/com.mycompany.myfirstglapp E/MapboxEventManager: Error Trying to load Staging Credentials: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
09-14 21:25:21.996 2844-2844/com.mycompany.myfirstglapp W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
09-14 21:25:22.263 2844-2844/com.mycompany.myfirstglapp I/art: Thread[1,tid=2844,Native,Thread*=0xb40f4500,peer=0x73828258,"main"] recursive attempt to load library "/data/app/com.mycompany.myfirstglapp-2/lib/x86/libmapbox-gl.so"
09-14 21:25:22.263 2844-2844/com.mycompany.myfirstglapp I/art: Thread[1,tid=2844,Native,Thread*=0xb40f4500,peer=0x73828258,"main"] recursive attempt to load library "/data/app/com.mycompany.myfirstglapp-2/lib/x86/libmapbox-gl.so"
09-14 21:25:22.294 2844-2844/com.mycompany.myfirstglapp E/OfflineManager: Failed to read the storage key: Attempt to invoke virtual method 'boolean android.os.Bundle.getBoolean(java.lang.String, boolean)' on a null object reference
09-14 21:25:22.359 2844-2844/com.mycompany.myfirstglapp I/com.mapbox.mapboxsdk.maps.MapView: MapView start Telemetry...
09-14 21:25:22.360 2844-2844/com.mycompany.myfirstglapp I/MapboxEventManager: Telemetry initialize() called...
09-14 21:25:22.360 2844-2844/com.mycompany.myfirstglapp I/MapboxEventManager: Mapbox Telemetry has already been initialized.

                                                                              [ 09-14 21:25:22.361  2844: 2844 D/         ]
                                                                              HostConnection::get() New Host Connection established 0xaaabfdc0, tid 2844
09-14 21:25:22.387 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: EGL Vendor: Android
09-14 21:25:22.387 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: EGL Version: 1.4 Android META-EGL
09-14 21:25:22.387 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: EGL Client APIs: OpenGL_ES
09-14 21:25:22.387 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: EGL Client Extensions: EGL_KHR_get_all_proc_addresses EGL_ANDROID_presentation_time EGL_KHR_swap_buffers_with_damage EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_fence_sync EGL_ANDROID_image_native_buffer 
09-14 21:25:22.387 2844-2844/com.mycompany.myfirstglapp W/mbgl: {ny.myfirstglapp}[Android]: In emulator! Enabling hacks :-(
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: Found 2 configs
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: Config 0:
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Caveat: 12344
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Conformant: 5
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Color: 32
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Red: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Green: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Blue: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Alpha: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Alpha mask: 0
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Depth: 24
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Stencil: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Sample buffers: 0
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Samples: 0
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: Config 1:
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Caveat: 12344
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Conformant: 5
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Color: 32
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Red: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Green: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Blue: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Alpha: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Alpha mask: 0
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Depth: 24
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Stencil: 8
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Sample buffers: 0
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: ...Samples: 0
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: Chosen config is 0
09-14 21:25:22.388 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: Chosen window format is 1
09-14 21:25:22.401 2844-2844/com.mycompany.myfirstglapp I/MapboxEventManager: flushEventsQueueImmediately() called...
09-14 21:25:22.403 2844-2844/com.mycompany.myfirstglapp D/MapboxEventManager: turnstile event pushed.
09-14 21:25:22.419 2844-2844/com.mycompany.myfirstglapp D/Network: Network
09-14 21:25:22.422 2844-2844/com.mycompany.myfirstglapp D/GPS Enabled: GPS Enabled
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.Context.checkPermission(java.lang.String, int, int)' on a null object reference
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.content.ContextWrapper.checkPermission(ContextWrapper.java:637)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.support.v4.content.ContextCompat.checkSelfPermission(ContextCompat.java:387)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at com.mycompany.myfirstglapp.GPSTracker.getLocation(GPSTracker.java:133)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at com.mycompany.myfirstglapp.GPSTracker.<init>(GPSTracker.java:62)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at com.mycompany.myfirstglapp.MainActivity.onCreate(MainActivity.java:102)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.app.Activity.performCreate(Activity.java:6237)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.app.ActivityThread.-wrap11(ActivityThread.java)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
09-14 21:25:22.434 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102)
09-14 21:25:22.435 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.os.Looper.loop(Looper.java:148)
09-14 21:25:22.435 2844-2844/com.mycompany.myfirstglapp W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5417)
09-14 21:25:22.435 2844-2844/com.mycompany.myfirstglapp W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
09-14 21:25:22.435 2844-2844/com.mycompany.myfirstglapp W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
09-14 21:25:22.435 2844-2844/com.mycompany.myfirstglapp W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
09-14 21:25:22.446 2844-2872/com.mycompany.myfirstglapp D/GzipRequestInterceptor: Compressing
09-14 21:25:22.450 2844-2877/com.mycompany.myfirstglapp D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
09-14 21:25:22.456 2844-2844/com.mycompany.myfirstglapp I/TelemetryService: onCreate() called
09-14 21:25:22.456 2844-2844/com.mycompany.myfirstglapp I/TelemetryService: onStartCommand() called
09-14 21:25:22.582 2844-2877/com.mycompany.myfirstglapp I/OpenGLRenderer: Initialized EGL, version 1.4

                                                                          [ 09-14 21:25:22.583  2844: 2877 D/         ]
                                                                          HostConnection::get() New Host Connection established 0xaa142310, tid 2877
09-14 21:25:22.699 2844-2877/com.mycompany.myfirstglapp W/EGL_emulation: eglSurfaceAttrib not implemented
09-14 21:25:22.699 2844-2877/com.mycompany.myfirstglapp W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xa0453360, error=EGL_SUCCESS

                                                                          [ 09-14 21:25:22.705  2878: 2903 D/         ]
                                                                          HostConnection::get() New Host Connection established 0xae4d28d0, tid 2903
09-14 21:25:22.829 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: GL Vendor: Google (Intel)
09-14 21:25:22.829 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: GL Renderer: Android Emulator OpenGL ES Translator (Intel(R) HD Graphics 2000)
09-14 21:25:22.830 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: GL Version: OpenGL ES 2.0 (3.1.0 - Build 9.17.10.4229)
09-14 21:25:22.830 2844-2844/com.mycompany.myfirstglapp I/mbgl: {ny.myfirstglapp}[OpenGL]: GL Extensions: GL_EXT_debug_marker GL_OES_EGL_image GL_OES_EGL_image_external GL_OES_depth24 GL_OES_depth32 GL_OES_element_index_uint GL_OES_texture_float GL_OES_texture_float_linear GL_OES_compressed_paletted_texture GL_OES_compressed_ETC1_RGB8_texture GL_OES_depth_texture GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_packed_depth_stencil GL_OES_vertex_half_float GL_OES_texture_npot GL_OES_rgb8_rgba8 ANDROID_EMU_CHECKSUM_HELPER_v1 
09-14 21:25:22.894 2844-2844/com.mycompany.myfirstglapp I/MapAsync:  is called
09-14 21:25:23.208 2844-2854/com.mycompany.myfirstglapp I/art: Background partial concurrent mark sweep GC freed 7816(378KB) AllocSpace objects, 0(0B) LOS objects, 39% free, 5MB/9MB, paused 9.556ms total 19.844ms
09-14 21:25:23.290 2844-2854/com.mycompany.myfirstglapp W/art: Suspending all threads took: 81.700ms
09-14 21:25:23.315 2844-2844/com.mycompany.myfirstglapp W/mbgl: {ny.myfirstglapp}[OpenGL]: Not using Vertex Array Objects
09-14 21:25:23.609 2844-2844/com.mycompany.myfirstglapp I/Choreographer: Skipped 45 frames!  The application may be doing too much work on its main thread.
09-14 21:25:23.809 2844-2923/com.mycompany.myfirstglapp D/com.mapbox.mapboxsdk.http.HTTPRequest: [HTTP] Request with response code = 304: Not Modified
09-14 21:25:23.811 2844-2872/com.mycompany.myfirstglapp D/MapboxEventManager: response code = 204 for events 2
09-14 21:25:24.072 2844-2935/com.mycompany.myfirstglapp V/com.mapbox.mapboxsdk.http.HTTPRequest: [HTTP] Request was successful (code = 200).
09-14 21:25:24.200 2844-2934/com.mycompany.myfirstglapp V/com.mapbox.mapboxsdk.http.HTTPRequest: [HTTP] Request was successful (code = 200).
09-14 21:25:24.237 2844-2923/com.mycompany.myfirstglapp V/com.mapbox.mapboxsdk.http.HTTPRequest: [HTTP] Request was successful (code = 200).
09-14 21:25:24.447 2844-2911/com.mycompany.myfirstglapp D/com.mapbox.mapboxsdk.http.HTTPRequest: [HTTP] Request with response code = 304: Not Modified
09-14 21:25:24.502 2844-2935/com.mycompany.myfirstglapp V/com.mapbox.mapboxsdk.http.HTTPRequest: [HTTP] Request was successful (code = 200).
09-14 21:25:24.525 2844-2892/com.mycompany.myfirstglapp D/com.mapbox.mapboxsdk.http.HTTPRequest: [HTTP] Request with response code = 304: Not Modified
09-14 21:25:24.541 2844-2913/com.mycompany.myfirstglapp D/com.mapbox.mapboxsdk.http.HTTPRequest: [HTTP] Request with response code = 304: Not Modified
09-14 21:25:31.922 2844-3063/com.mycompany.myfirstglapp D/MapboxEventManager: No events in the queue to send so returning.
java
android
share
EN

回答 1

Stack Overflow用户

回答已采纳

发布于 2016-09-15 07:56:41

您从日志猫发布的唯一堆栈跟踪是针对错误的

代码语言：javascript
复制
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.Context.checkPermission(java.lang.String, int, int)' on a null object reference

当你往下看几行时，你会发现

代码语言：javascript
复制
at com.mycompany.myfirstglapp.GPSTracker.getLocation(GPSTracker.java:133)

这意味着错误是由于GPSTracker.java中的第133行上的某些内容而发生的。这位于您的GPSTracker类的getLocation()方法中。您需要查看此行代码，并使用调试器来确定该行代码中的哪个变量为null。由于堆栈跟踪显示了调用堆栈中的其他方法，因此问题很可能出在传递给getLocation()方法的一个参数上。

票数 0
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/39480154

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