kotlin 扩展SwitchMaterial和NPE发生

7hiiyaii  于 2023-04-07  发布在  Kotlin
关注(0)|答案(1)|浏览(136)

我正在尝试在Android中自定义SwitchMaterial类，如下所示

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

}

我在活动xml中使用TipSwitchMaterial，如下所示：

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:isScrollContainer="true"
    tools:context=".SidActivity">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

...

        <com.omnieyes.omnilite.view.TipSwitchMaterial
            android:id="@+id/event_record_sort_switch"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="8dp"
            android:text="@string/sort"
            android:tooltipText="@string/tooltip_sort"
            app:layout_constraintBottom_toBottomOf="@+id/predict_button"
            app:layout_constraintEnd_toStartOf="@id/predict_button"
            app:layout_constraintHorizontal_chainStyle="packed"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/predict_button" />
...

然而，NPE将在进入该活动后立即发生：

2023-03-23 15:21:36.630 17706-17706/? E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.omnieyes.omnilite, PID: 17706
    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:455)
        at androidx.appcompat.widget.SwitchCompat.makeLayout(SwitchCompat.java:982)
        at androidx.appcompat.widget.SwitchCompat.onMeasure(SwitchCompat.java:905)
        at android.view.View.measure(View.java:25466)
        at androidx.constraintlayout.widget.ConstraintLayout$Measurer.measure(ConstraintLayout.java:811)
        at androidx.constraintlayout.core.widgets.analyzer.BasicMeasure.measure(BasicMeasure.java:466)
        at androidx.constraintlayout.core.widgets.analyzer.BasicMeasure.measureChildren(BasicMeasure.java:134)
        at androidx.constraintlayout.core.widgets.analyzer.BasicMeasure.solverMeasure(BasicMeasure.java:278)
        at androidx.constraintlayout.core.widgets.ConstraintWidgetContainer.measure(ConstraintWidgetContainer.java:120)
        at androidx.constraintlayout.widget.ConstraintLayout.resolveSystem(ConstraintLayout.java:1594)
        at androidx.constraintlayout.widget.ConstraintLayout.onMeasure(ConstraintLayout.java:1708)
        at android.view.View.measure(View.java:25466)
        at android.widget.ScrollView.measureChildWithMargins(ScrollView.java:1412)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at android.widget.ScrollView.onMeasure(ScrollView.java:452)
        at android.view.View.measure(View.java:25466)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6957)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at androidx.appcompat.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:145)
        at android.view.View.measure(View.java:25466)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6957)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1552)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:842)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:721)
        at android.view.View.measure(View.java:25466)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6957)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at android.view.View.measure(View.java:25466)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6957)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1552)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:842)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:721)
        at android.view.View.measure(View.java:25466)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6957)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at com.android.internal.policy.DecorView.onMeasure(DecorView.java:747)
        at android.view.View.measure(View.java:25466)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:3397)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:2228)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2486)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1952)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:8171)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:972)
        at android.view.Choreographer.doCallbacks(Choreographer.java:796)
        at android.view.Choreographer.doFrame(Choreographer.java:731)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:957)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

我这样做是因为我想在this post中应用类似点击的工具提示，它在OnClickListener中执行perfromLongClick()。我试图稍微改变他的方式。我计划在init{}块中这样做：

init {
        // so we can click and show its tooltip; a long-click still does
        setOnClickListener { performLongClick() }
    }

它与一个扩展TextView的类一起工作。请帮助，谢谢。
我已经列出了我在上面尝试过的东西。我找不到任何与SwitchMaterial相关的帖子或教程。也许没有必要这样做？

编辑：添加build.gradle文件

我的build.gradle文件如下：

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-android-extensions'
}

android {
    compileSdk 31

    defaultConfig {
        applicationId "xxx"
        minSdk 26
        targetSdk 31
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

        ndk {
            abiFilters "armeabi", "armeabi-v7a", "x86", "mips"
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    packagingOptions {
        exclude 'AndroidManifest.xml'
    }
}

dependencies {
    implementation 'androidx.appcompat:appcompat:1.4.1'
    implementation 'com.google.android.material:material:1.5.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.3'
    implementation project(path: ':opencv')
    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.4'
    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.6.4'
    implementation 'com.google.code.gson:gson:2.10'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
    implementation 'androidx.core:core-ktx:1.3.2'
    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation group: 'commons-io', name: 'commons-io', version: '2.6'
    implementation group: 'org.javatuples', name: 'javatuples', version: '1.2'
    implementation('com.squareup.okhttp3:okhttp:4.9.3')
    implementation('org.apache.commons:commons-csv:1.5')
    implementation files('libs/openCVLibrary330-v1.1-release.aar')

    //firebase, choose for kotlin and java or Both.
    implementation 'com.google.firebase:firebase-crashlytics-ktx:18.3.0'
    implementation 'com.google.firebase:firebase-crashlytics'
}
kotlin

1条答案

按热度按时间
ijnw1ujt

ijnw1ujt1#

在系统/库代码中发生的这些类型的错误可能很难跟踪。
我只能通过1）强制defStyleAttr为零，或2）强制布局文件中的textOn属性为空来重现您的错误（android:textOn="@null"）。这告诉我你正在丢失属性或修改样式，这样textOn和，可能，textOff显示为null。您可以通过在XML布局中设置android:textOn="On"和android:textOff="Off"来确定这是问题的根源。（但这不是修复方法。）
那么，我为什么要这么说呢？如果我们以相反的顺序获取堆栈跟踪中最上面的程序引用行，我们可以看到崩溃所涉及的代码。

at androidx.appcompat.widget.SwitchCompat.onMeasure(SwitchCompat.java:905)
    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        ...
        if (mOnLayout == null) {
            mOnLayout = makeLayout(mTextOnTransformed); // Line 905
        }
        ...
    }

    at androidx.appcompat.widget.SwitchCompat.makeLayout(SwitchCompat.java:982)
    private Layout makeLayout(CharSequence transformedText) {
        return new StaticLayout(transformedText, mTextPaint,
                transformedText != null
                        ? (int) Math.ceil(Layout.getDesiredWidth(transformedText, mTextPaint)) : 0, // Line 982
                Layout.Alignment.ALIGN_NORMAL, 1.f, 0, true);
    }


    at android.text.StaticLayout.<init>(StaticLayout.java:455)
            this(source, 0, source.length(), paint, width, align, // Line 455
         spacingmult, spacingadd, includepad);

如果我们在 * StaticLayout.java * 的第455行设置一个断点，我们可以看到source为null，这直接导致了崩溃。
java.lang.NullPointerException:尝试对空对象引用调用接口方法“intjava.lang.CharSequence.length（）”
追溯source变量的来源，我们看到它来自mTextOnTransformed（SwitchCompat.java的第905行）。mTextOnTransformed唯一被设置的地方是在下面的代码中：

In SwtichCompat.hava:
    private void setTextOnInternal(CharSequence textOn) {
        ...
        mTextOnTransformed = doTransformForOnOffText(textOn);
        ...
    }

而textOn是当开关为“on”且为null时显示的文本。
我不能告诉你具体如何纠正这个错误，但仔细看看你有什么接触开关和它的属性，包括样式，试图找出哪里出了问题。

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