以编程方式添加 SwitchCompat 错误

Question

I'm trying to add android.support.v7.widget.SwitchCompat programmatically and I'm getting this error:

java.lang.NullPointerException: Attempt to invoke interface method 'int java.lang.CharSequence.length()' on a null object reference
at android.text.StaticLayout.<init>(StaticLayout.java:422)
at android.support.v7.widget.SwitchCompat.makeLayout(SwitchCompat.java:602)
at android.support.v7.widget.SwitchCompat.onMeasure(SwitchCompat.java:526)
at android.view.View.measure(View.java:18799)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1458)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:746)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:18799)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1458)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:746)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:18799)
at android.support.v7.widget.Toolbar.measureChildCollapseMargins(Toolbar.java:1218)
at android.support.v7.widget.Toolbar.onMeasure(Toolbar.java:1326)
at android.view.View.measure(View.java:18799)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1458)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:746)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.support.design.widget.AppBarLayout.onMeasure(AppBarLayout.java:199)
at android.view.View.measure(View.java:18799)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:668)
at android.support.design.widget.AppBarLayout$Behavior.onMeasureChild(AppBarLayout.java:888)
at android.support.design.widget.AppBarLayout$Behavior.onMeasureChild(AppBarLayout.java:652)
at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:733)
at android.view.View.measure(View.java:18799)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:18799)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1458)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:746)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:18799)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.view.View.measure(View.java:18799)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1458)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:746)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:18799)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2899)
at android.view.View.measure(View.java:18799)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2108)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1224)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1460)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1115)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6023)
at android.view.Choreographer$CallbackRecord.run(Chore

but when I'm using Switch everything is ok. why is this happening? this is my code:

SwitchCompat switchBox = (SwitchCompat) LayoutInflater.from(getApplicationContext()).inflate(R.layout.checkbox, null);
switchBox.setId(i);
Typeface typeface = Typeface.createFromAsset(getAssets(), "iransansfont.ttf");
switchBox.setText(convert_num((nodesModelArrayList.get(i).type ? "بیمارستان " : "مطب ") + nodesModelArrayList.get(i).node_name + ": " + nodesModelArrayList.get(i).stat));
switchBox.setTypeface(typeface);
switchBox.setOnCheckedChangeListener(onCheckedChangeListener);
linearLayout.addView(switchBox);
switchBox.setChecked(true);

Answer 1

Use an activity context and not application context for inflating views so that eg themes work.

The crash is because the textOn and textOff labels are null that would normally get their default values from a theme.

Answer 2

I had the same issue trying to create the SwitchCompat like this:

SwitchCompat switchCompat = new SwitchCompat(getContext());
switchCompat.setText(...);

Fixed it by inflating it as an XML layout:

layoutInflater.inflate(R.layout.view_switch_compat, parent, false);

And view_switch_compat.xml contains:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.SwitchCompat 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/switchCompat"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

Hope it helps someone :-)

Answer 3

I had the same issue with a custom SwitchMaterial.

The problem was that I used 0 as the style by default.

Changing it to com.google.android.material.R.attr.switchStyle solved the problem.

class MySwitchMaterial @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = com.google.android.material.R.attr.switchStyle,
) : SwitchMaterial(context, attrs, defStyleAttr) {