当切换图例可见性时，TChart崩溃

Question

当我在不同的TChart系列之间切换时，如果在运行之间切换图例可见性，我会得到一个异常。例如

1. 显示条形图。传说可见。
显示
2. 饼状图。传说看不见。
3. 显示条形图。传说可见。
4. 崩溃!

这是在重新绘制控件时导致未捕获异常的行:

chart.getLegend().setVisible(true);

每次运行之间，我做以下操作:

chart.setAutoRepaint(false);
chart.removeAllSeries();
// Build chart...
chart.setAutoRepaint(true);
chart.refreshControl();

TChart专家们，我怎样才能避免这种崩溃?

Answer 1

这对我来说不是崩溃。我可以多次从Bar切换到Pie，没有问题。

package com.steema.test;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.Spinner;
import com.steema.teechart.TChart;
import com.steema.teechart.styles.Bar;
import com.steema.teechart.styles.Pie;
import com.steema.teechart.themes.ThemesList;
public class AndroidTestActivity extends Activity implements OnItemSelectedListener{
    private TChart tChart1;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        LinearLayout group = (LinearLayout) findViewById(R.id.linearLayoutTchart);
        tChart1 = new TChart(this);
        group.addView(tChart1);
        ThemesList.applyTheme(tChart1.getChart(), 1);
        Spinner spinner = (Spinner) findViewById(R.id.series_spinner);
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.series_array, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);
    }
    @Override
    public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
        tChart1.setAutoRepaint(false);
        tChart1.removeAllSeries();
        switch (arg2) {
        case 0:
            Bar bar1 = new Bar(tChart1.getChart());
            bar1.fillSampleValues();
            tChart1.getLegend().setVisible(true);
            break;
        case 1:
            Pie pie1 = new Pie(tChart1.getChart());
            pie1.fillSampleValues();
            tChart1.getLegend().setVisible(false);
            break;
        }
        tChart1.setAutoRepaint(true);
        tChart1.refreshControl();
    }
    @Override
    public void onNothingSelected(AdapterView<?> arg0) {
    }
}

这是我的main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <TextView  
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" 
        android:text="@string/hello"/>
    <Spinner android:id="@+id/series_spinner"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
    <LinearLayout android:id="@+id/linearLayoutTchart" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content"/>
</LinearLayout>

这里是strings。xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">TeeChartJava for Android testing application!</string>
    <string name="app_name">AndroidTest</string>
    <string-array name="series_array">
        <item>Bar</item>
        <item>Pie</item>
    </string-array>
</resources>

---

更新1:

如果我把上面的tChart1.getLegend().setSeries(tChart1.getSeries(0));加到case 1中:

    case 1:
        Pie pie1 = new Pie(tChart1.getChart());
        pie1.fillSampleValues();
        tChart1.getLegend().setSeries(tChart1.getSeries(0));
        tChart1.getLegend().setVisible(false);
        break;

然后我得到一个错误消息，当选择回栏系列。这是因为我们将图例设置为使用Pie系列(第一次选择Pie时)，在选择Bar时删除了该Pie系列，但图例仍然引用已删除的Pie系列。请检查图例中是否设置了有效的系列。即:

    case 0:
        Bar bar1 = new Bar(tChart1.getChart());
        bar1.fillSampleValues();
        tChart1.getLegend().setSeries(tChart1.getSeries(0));
        tChart1.getLegend().setVisible(true);
        break;
    case 1:
        Pie pie1 = new Pie(tChart1.getChart());
        pie1.fillSampleValues();
        tChart1.getLegend().setSeries(tChart1.getSeries(0));
        tChart1.getLegend().setVisible(false);
        break;

下一版本将在清除系列列表后在removeAllSeries()中设置getLegend().setSeries(null)