优化细节

lib/src/main/java/com/king/zxing/CaptureActivity.java

@@ -55,7 +55,10 @@ public class CaptureActivity extends AppCompatActivity implements OnCaptureCallb
      */
     public void initUI(){
         surfaceView = findViewById(getSurfaceViewId());
-        viewfinderView = findViewById(getViewfinderViewId());
+        int viewfinderViewId = getViewfinderViewId();
+        if(viewfinderViewId != 0){
+            viewfinderView = findViewById(viewfinderViewId);
+        }
         int ivTorchId = getIvTorchId();
         if(ivTorchId != 0){
             ivTorch = findViewById(ivTorchId);
@@ -88,7 +91,7 @@ public class CaptureActivity extends AppCompatActivity implements OnCaptureCallb
 
     /**
      * {@link #viewfinderView} 的 ID
-     * @return
+     * @return 默认返回{@code R.id.viewfinderView}, 如果不需要扫码框可以返回0
      */
     public int getViewfinderViewId(){
         return R.id.viewfinderView;