小编fra*_*cis的帖子

我是d3.js的新手,我可以发现d3 api提供了通过方法获得特定长度的svg点的方法,getPointAtLength(l)但我正在寻找一种方法来计算d3中特定点的路径长度？

如果有的话,请分享您的建议.

我是android编程的新手.我试图创建一个秒表应用程序,但最近我在布局中出错.我已经调试了这个布局错误2天仍然无法找到解决方案.我不认为这是IDE问题,因为当我使用手机测试它时,程序停止(错误).

请看下面的错误:

android.widget.LinearLayout.forceUniformHeight(LinearLayout.java:1380)的java.lang.NullPointerException at

android.widget.LinearLayout.measureHorizo​​ntal(LinearLayout.java:1368)android.view.TableRow.onMeasure(TableRow.java:114)在android.view.vision.measure.View上的android.view.View.measure(View.java:17430) .measureChildWithMargins(ViewGroup.java:5463)位于android.widget.Lable中的android.widget.LinearLayout.measureChildBefore(LineLayout.java:1436)以及android.widget.LinearLayout.measureVertical(LinearLayout.)的android.widget.TableLayout.measureChildBeforeLayout(TableLayout.java:464). java:722)android.widget.TableLayout.measureVertical(TableLayout.java:476)android.widget.TableLayout.onMeasure(TableLayout.java:439)android.view.View.measure(View.java:17430)at在Android.widget.LinearLayout的android.view.View.measure(View.java:17430)android.widget.FrameLayout.onMeasure(FrameLayout.java:430)的android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) android的android.widget.LinearLayout.onMeasure(LinearLayout.java:613).measureVertical(LinearLayout.java:875).在android.view.View.measure的android.widget.LinearLayout.onMeasure(LinearLayout.java:613)的android.widget.LinearLayout.measureVertical(LinearLayout.java:875)上查看View.View.measure(View.java:17430) (View.java:17430)

这是我的代码:

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MainActivity"
    style="@style/activity_style">

        <TableRow
            android:layout_height="0dp"
            android:layout_width="match_parent"
            android:layout_weight="2">
            <EditText
                style="@style/edit_text_timer"
                android:id="@+id/etHour"
                android:hint="@string/initial_value"
                android:layout_height="match_parent"
                android:layout_width="0dp"
                android:layout_weight="3"
                android:layout_column="6"
             />

            <TextView
                android:id="@+id/tvColon"
                android:layout_height="match_parent"
                android:layout_width="0dp"
                android:text="@string/colon_text_view"
                android:gravity="center"
                android:textColor="#e7ff00"
                android:textSize="30sp"
                android:layout_weight="1"/>

            <EditText
                style="@style/edit_text_timer"
                android:id="@+id/etMinute"
                android:hint="@string/initial_value"
                android:layout_height="match_parent"
                android:layout_width="0dp"
                android:layout_weight="3"
                android:layout_column="13" />


            <TextView
                android:id="@id/tvColon"
                android:layout_height="match_parent"
                android:layout_width="0dp"
                android:text="@string/colon_text_view"
                android:gravity="center"
                android:textColor="#e7ff00"
                android:textSize="30sp"
                android:layout_weight="1"
                android:layout_column="18" />

            <EditText
                style="@style/edit_text_timer"
                android:id="@+id/etSecond"
                android:hint="@string/initial_value"
                android:layout_height="match_parent"
                android:layout_width="0dp"
                android:layout_weight="3"
                />
        </TableRow>

        <TableRow
            android:layout_height="0dp"
            android:layout_weight="1"
            android:layout_width="match_parent">
            <Button …