Question

我以这个https://github.com/PhilJay/MPAndroidChart/blob/master/MPChartExample/src/main/java/com/xxmassdeveloper/mpchartexample/LineChartTime.java为例我适应了我的需要。问题在于，要在X轴上绘制数据，它需要一个浮点数，然后从long转换为float会丢失数据。该示例中的技巧是将毫秒时间转换为HOURLY，这样就不会丢失数据，但是我需要转换为DAILY，我尝试过但无法获得结果

我尝试将TimeUnit.HOURS.toMillis((long) value);更改为TimeUnit.DAYS.toMillis((long) value);，并添加了timeInHours = TimeUnit.DAYS.toMillis(mDate.getTime());

public class ChartDailyActivity extends AppCompatActivity {

    private LineChart chart;
    DBOpenHelper mDB;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_chart_daily);

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        setChart();

    }


    public void setChart(){

        chart = findViewById(R.id.chart1);

        XAxis xAxis = chart.getXAxis();
        xAxis.setPosition(XAxis.XAxisPosition.TOP_INSIDE);
        xAxis.setTextSize(10f);
        xAxis.setTextColor(Color.WHITE);
        xAxis.setDrawAxisLine(false);
        xAxis.setDrawGridLines(true);
        xAxis.setTextColor(Color.rgb(255, 192, 56));
        xAxis.setCenterAxisLabels(true);
        //xAxis.setSpaceMin(1000f*60f*60f*24f);

        xAxis.setValueFormatter(new IAxisValueFormatter() {

            private final SimpleDateFormat mFormat = new SimpleDateFormat("dd/MM/yy", Locale.ITALIAN);

            @Override
            public String getFormattedValue(float value, AxisBase axis) {

                long millis = TimeUnit.DAYS.toMillis((long) value);

                return mFormat.format(new Date(millis));

            }

        });

        mDB = new DBOpenHelper(this);

        YAxis leftAxis = chart.getAxisLeft();
        leftAxis.setPosition(YAxis.YAxisLabelPosition.INSIDE_CHART);
        leftAxis.setTextColor(ColorTemplate.getHoloBlue());
        leftAxis.setDrawGridLines(true);
        leftAxis.setGranularityEnabled(true);
        leftAxis.setAxisMinimum(0f);
        leftAxis.setAxisMaximum((float) mDB.queryMaxTotaleBevuto());
        leftAxis.setYOffset(-9f);
        leftAxis.setTextColor(Color.rgb(255, 192, 56));

        YAxis rightAxis = chart.getAxisRight();
        rightAxis.setEnabled(false);

        setData();

    }

    private void setData() {

        ArrayList<Entry> values = new ArrayList<>();

        ArrayList xList = new ArrayList<Integer>();
        ArrayList yList = new ArrayList<String>();

        DBOpenHelper mDB = new DBOpenHelper(this);

        xList = mDB.queryTotaleBevutoData();
        yList = mDB.queryTotaleBevuto();

        float flX, flY;
        int intX, intY;

        for(int x=0; x<xList.size(); x++){

            String givenDateString = (String)xList.get(x);
            SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yy");

            long timeInHours = 0;

            try {

                Date mDate = sdf.parse(givenDateString);
                //Log.d("XLOGGIN:", "Date = " + givenDateString );
                timeInHours = TimeUnit.DAYS.toMillis(mDate.getTime());
                //timeInMilliseconds = mDate.getTime();

            } catch (ParseException e) {

                e.printStackTrace();

            }

            intX = (int)timeInHours;
            intY = (int)yList.get(x);

            flX = (float)intX;
            flY = (float)intY;
/*
            Log.d("XLOGGIN:Long", Long.toString(timeInMilliseconds));
            Log.d("XLOGGIN:intX", Integer.toString(intX));
            Log.d("XLOGGIN:flX", Float.toString(flX));
*/
            values.add(new Entry(flX, flY));

        }

        // create a dataset and give it a type
        LineDataSet set1 = new LineDataSet(values, "Drinked ml/Day");
        set1.setAxisDependency(YAxis.AxisDependency.LEFT);
        set1.setColor(ColorTemplate.getHoloBlue());
        set1.setValueTextColor(ColorTemplate.getHoloBlue());
        set1.setLineWidth(1.5f);
        set1.setDrawCircles(false);
        set1.setDrawValues(false);
        set1.setFillAlpha(65);
        set1.setFillColor(ColorTemplate.getHoloBlue());
        set1.setHighLightColor(Color.rgb(244, 117, 117));
        set1.setDrawCircleHole(false);

        // create a data object with the data sets
        LineData data = new LineData(set1);
        data.setValueTextColor(Color.WHITE);
        data.setValueTextSize(9f);

        // set data
        chart.setData(data);
    }

}

图表绘制了错误的日期时间（所有日期均为1970年1月1日），并且该线为水平线

Answer 1

您没有将时间戳转换为等效日期。这是您应该如何做（在setData（）期间）：

        try {

            Date mDate = sdf.parse(givenDateString);
            //Log.d("XLOGGIN:", "Date = " + givenDateString );
            timeInDays = TimeUnit.MILLISECONDS.toDays(mDate.getTime());
            //timeInMilliseconds = mDate.getTime();

        } catch (ParseException e) {

            e.printStackTrace();

        }

MPAndroidChart中的DateTime问题

1 个答案: