app/src/main/res/layout/layout_tcpclient.xml
@@ -103,6 +103,12 @@
                android:layout_marginEnd="10dp"
                android:id="@+id/btn_stop_exam"
                android:text="结束考试"/>
              <Button
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginEnd="10dp"
                    android:id="@+id/btn_keepalive"
                    android:text="心跳"/>
        </TableRow>
    </TableLayout>