如何在 Fragment 中插入 MPAndroidChart

Question

我正在尝试在 Android studio 中以片段形式显示图表。

创建图表的函数是“setChart_Parameters()”

当我尝试在 Activity 中插入图表时，一切正常，但当我在片段中尝试相同时，应用程序关闭。谁能帮帮我？

我怀疑我在图表函数中做错了什么。当我不在片段中调用图表创建函数时，应用程序不会关闭。

这是我的片段代码

   fragment_chart.xml

<androidx.constraintlayout.widget.ConstraintLayout
    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="wrap_content"
    tools:context=".ChartFragment"
    >

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Data Graph"
        android:textSize="20dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        />

    <com.github.mikephil.charting.charts.LineChart
        android:id="@+id/logchart"
        android:layout_width="match_parent"
        android:layout_height="300dp"
        android:layout_marginTop="20dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2"
        />

</androidx.constraintlayout.widget.ConstraintLayout>

"ChartFragment.kt"

class ChartFragment : Fragment() {

    private var param1: String? = null
    private var param2: String? = null
    var dataPoints = 30

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            param1 = it.getString(ARG_PARAM1)
            param2 = it.getString(ARG_PARAM2)
        }

        Log.d("FragTest","Chart setting")

    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        Log.d("FragTest","Chart setting")
        var view: View = inflater.inflate(R.layout.fragment_chart, container, false)
        setChart_Parameters()
        return view
    }

    companion object {
        @JvmStatic
        fun newInstance(param1: String, param2: String) =
            ChartFragment().apply {
                arguments = Bundle().apply {
                    putString(ARG_PARAM1, param1)
                    putString(ARG_PARAM2, param2)
            }
        }
    }
    private fun setChart_Parameters()
    {
        logchart.apply{
            setBackgroundColor(Color.WHITE)
            description.isEnabled=false
            setTouchEnabled(true)
            //setOnChartValueSelectedListener(this)
            setDrawGridBackground(false)
            isDragEnabled = true
            setScaleEnabled(true)
            setPinchZoom(true)
        }
        var legend: Legend = logchart.legend.apply {
            form = Legend.LegendForm.LINE
            textSize = 11f
            textColor = Color.WHITE
            verticalAlignment = Legend.LegendVerticalAlignment.BOTTOM
            horizontalAlignment = Legend.LegendHorizontalAlignment.LEFT
            orientation = Legend.LegendOrientation.HORIZONTAL
            setDrawInside(false)
        }
        var xAxis: XAxis = logchart.xAxis
        logchart.axisRight.isEnabled = false
        var yAxis: YAxis = logchart.axisLeft.apply {
            enableGridDashedLine(10f, 10f, 0f)
            axisMaximum = 200f
            axisMinimum = -50f
        }
        var llAXis = LimitLine(9f, "Index 10").apply {
            setLineWidth(4f)
            enableDashedLine(10f, 10f, 0f)
            setLabelPosition(LimitLine.LimitLabelPosition.RIGHT_BOTTOM)
            setTextSize(10f)
        }
        val ll1 = LimitLine(150f, "Upper Limit").apply {
            lineWidth = 4f
            enableDashedLine(10f, 10f, 0f)
            labelPosition = LimitLine.LimitLabelPosition.RIGHT_TOP
            textSize = 10f
        }
        val ll2 = LimitLine(-30f, "Lower Limit").apply{
            lineWidth = 4f
            enableDashedLine(10f, 10f, 0f)
            labelPosition = LimitLine.LimitLabelPosition.RIGHT_BOTTOM
            textSize = 10f
        }
        var value1 = ArrayList<Entry>().apply {
            for(i in 1..dataPoints){
                add(Entry(i.toFloat(), (i+20).toFloat()))
            }
        }
        var value2 = ArrayList<Entry>().apply {
            for(i in 1..dataPoints){
                add(Entry(i.toFloat(), (i+30).toFloat()))
            }
        }
        val set1: LineDataSet
        val set2: LineDataSet
        if (logchart.data != null && logchart.data.dataSetCount > 0
        ) {
            set1 = logchart.data.getDataSetByIndex(0) as LineDataSet
            set2 = logchart.data.getDataSetByIndex(1) as LineDataSet
            set1.values = value1
            set2.values = value2
            logchart.data.notifyDataChanged()
            logchart.notifyDataSetChanged()
        } else {
            set1 = LineDataSet(value1, "Temperature")
            set1.setDrawIcons(false)
            set1.enableDashedLine(10f, 5f, 0f)
            set1.enableDashedHighlightLine(10f, 5f, 0f)
            set1.color = Color.RED
            set1.setCircleColor(Color.RED)
            set1.lineWidth = 2f
            set1.circleRadius = 3f
            set1.setDrawCircleHole(false)
            set1.valueTextSize = 9f
            set1.setDrawFilled(true)
            set1.formLineWidth = 1f
            set1.formLineDashEffect = DashPathEffect(floatArrayOf(10f, 5f), 0f)
            set1.formSize = 10f

            set2 = LineDataSet(value2, "Humidity")
            set2.setDrawIcons(false)
            set2.enableDashedLine(10f, 5f, 0f)
            set2.enableDashedHighlightLine(10f, 5f, 0f)
            set2.color = Color.BLUE
            set2.setCircleColor(Color.BLUE)
            set2.lineWidth = 2f
            set2.circleRadius = 3f
            set2.setDrawCircleHole(false)
            set2.valueTextSize = 9f
            set2.setDrawFilled(true)
            set2.formLineWidth = 1f
            set2.formLineDashEffect = DashPathEffect(floatArrayOf(10f, 5f), 0f)
            set2.formSize = 15f

            val dataSets = LineData(set1, set2)
            logchart.data = dataSets
        }
    }
}

我的主要activity如下：

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_data)
    
        Log.d("FragTest","Fragment begin")
        var fragVar = ChartFragment()
        supportFragmentManager.beginTransaction().apply {
            replace(R.id.chartFrame, fragVar) 
            commit()
        }
    }
}

Answer 1

尝试将 setChart_Parameters() 移动到 onViewCreated()。因为在onCreateView()完成之前，无法到达布局中的所有视图。

如何在 Fragment 中插入 MPAndroidChart

How to insert MPAndroidChart in Fragment

android

android-fragments

kotlin

android-studio