本文介绍了将DefaultCategoryDataset转换为CategoryDataset的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我试图创建一个基本的barchart，当我编译它给出一个错误像
这里是我的代码
import java.awt.Color;
import java.awt.Dimension;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.ui.ApplicationFrame;
public class BarChartDemo extends
public BarChartDemo（final String title）{
super（title）;
final CategoryDataset dataset = createDataset（）;
final JFreeChart chart = createChart（dataset）;
final ChartPanel chartPanel = new ChartPanel（chart）;
chartPanel.setPreferredSize（new Dimension（500，270））;
setContentPane（chartPanel）;
}
public static void main（String [] args）{
BarChartDemo br = new BarChartDemo（title）;
br.createDataset（）;
}
private CategoryDataset createDataset（）{
//行键...
final String series1 =First;
final String series2 =Second;
final String series3 =Third;
//列键...
final String category1 =类别1;
final String category2 =Category 2;
final String category3 =Category 3;
final String category4 =Category 4;
final String category5 =Category 5;
//创建数据集...
final DefaultCategoryDataset dataset = new DefaultCategoryDataset（）;
dataset.addValue（1.0，series1，category1）;
dataset.addValue（4.0，series1，category2）;
dataset.addValue（3.0，series1，category3）;
dataset.addValue（5.0，series1，category4）;
dataset.addValue（5.0，series1，category5）;
dataset.addValue（5.0，series2，category1）;
dataset.addValue（7.0，series2，category2）;
dataset.addValue（6.0，series2，category3）;
dataset.addValue（8.0，series2，category4）;
dataset.addValue（4.0，series2，category5）;
dataset.addValue（4.0，series3，category1）;
dataset.addValue（3.0，series3，category2）;
dataset.addValue（2.0，series3，category3）;
dataset.addValue（3.0，series3，category4）;
dataset.addValue（6.0，series3，category5）;
返回数据集;
}
private JFreeChart createChart（final CategoryDataset dataset）{
//创建图表...
最后JFreeChart图表= ChartFactory.createBarChart（
条形图演示，//图表标题
类别，//域轴标签
Value，（org.jfree.data。 Category dataset）dataset，
PlotOrientation.VERTICAL，// orientation
true，// include legend
true，// tooltips？
false // URLs？
）;
chart.setBackgroundPaint（Color.white）;
return chart;
}
}
为什么我们不能强制转换DefaultCategoryDataset到CategoryDataset，谁能解决这个问题？
解决方案
测试代码：
import java .awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.ui.ApplicationFrame;
public class BarChartDemo extends ApplicationFrame {
public BarChartDemo（final String title）{
super（title）;
final CategoryDataset dataset = createDataset（）;
final JFreeChart chart = createChart（dataset）;
final ChartPanel chartPanel = new ChartPanel（chart）{
@Override
public Dimension getPreferredSize（）{
return new Dimension（500，270）;
}
}
setContentPane（chartPanel）;
pack（）;
setVisible（true）;
}
public static void main（String [] args）{
EventQueue.invokeLater（new Runnable（）{
@Override
public void run（）{
BarChartDemo br = new BarChartDemo（title）;
}
}）;
}
private CategoryDataset createDataset（）{
// row keys ...
final String series1 =First;
final String series2 =Second
final String series3 =Third;
//列键...
final String category1 =类别1;
final String category2 =Category 2;
final String category3 =Category 3;
final String category4 =Category 4;
final String category5 =Category 5;
//创建数据集...
final DefaultCategoryDataset dataset = new DefaultCategoryDataset（）;
dataset.addValue（1.0，series1，category1）;
dataset.addValue（4.0，series1，category2）;
dataset.addValue（3.0，series1，category3）;
dataset.addValue（5.0，series1，category4）;
dataset.addValue（5.0，series1，category5）;
dataset.addValue（5.0，series2，category1）;
dataset.addValue（7.0，series2，category2）;
dataset.addValue（6.0，series2，category3）;
dataset.addValue（8.0，series2，category4）;
dataset.addValue（4.0，series2，category5）;
dataset.addValue（4.0，series3，category1）;
dataset.addValue（3.0，series3，category2）;
dataset.addValue（2.0，series3，category3）;
dataset.addValue（3.0，series3，category4）;
dataset.addValue（6.0，series3，category5）;
返回数据集;
}
private JFreeChart createChart（final CategoryDataset dataset）{
//创建图表...
final JFreeChart chart = ChartFactory.createBarChart（
Bar Chart Demo，//图表标题
Category，//域轴标签
Value，数据集，
PlotOrientation.VERTICAL，// orientation
true， // include legend
true，// tooltips？
false // URLs？
）;
chart.setBackgroundPaint（Color.white）;
return chart;
}
}
I'm trying to create a basic barchart and when I compile it gives an error like
here is my code
package barchart;
import java.awt.Color;
import java.awt.Dimension;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.ui.ApplicationFrame;
public class BarChartDemo extends
public BarChartDemo(final String title) {
super(title);
final CategoryDataset dataset = createDataset();
final JFreeChart chart = createChart(dataset);
final ChartPanel chartPanel = new ChartPanel(chart);
chartPanel.setPreferredSize(new Dimension(500, 270));
setContentPane(chartPanel);
}
public static void main(String[] args) {
BarChartDemo br = new BarChartDemo("title");
br.createDataset();
}
private CategoryDataset createDataset() {
// row keys...
final String series1 = "First";
final String series2 = "Second";
final String series3 = "Third";
// column keys...
final String category1 = "Category 1";
final String category2 = "Category 2";
final String category3 = "Category 3";
final String category4 = "Category 4";
final String category5 = "Category 5";
// create the dataset...
final DefaultCategoryDataset dataset = new DefaultCategoryDataset();
dataset.addValue(1.0, series1, category1);
dataset.addValue(4.0, series1, category2);
dataset.addValue(3.0, series1, category3);
dataset.addValue(5.0, series1, category4);
dataset.addValue(5.0, series1, category5);
dataset.addValue(5.0, series2, category1);
dataset.addValue(7.0, series2, category2);
dataset.addValue(6.0, series2, category3);
dataset.addValue(8.0, series2, category4);
dataset.addValue(4.0, series2, category5);
dataset.addValue(4.0, series3, category1);
dataset.addValue(3.0, series3, category2);
dataset.addValue(2.0, series3, category3);
dataset.addValue(3.0, series3, category4);
dataset.addValue(6.0, series3, category5);
return dataset;
}
private JFreeChart createChart(final CategoryDataset dataset) {
// create the chart...
final JFreeChart chart = ChartFactory.createBarChart(
"Bar Chart Demo", // chart title
"Category", // domain axis label
"Value", (org.jfree.data.CategoryDataset) dataset,
PlotOrientation.VERTICAL, // orientation
true, // include legend
true, // tooltips?
false // URLs?
);
chart.setBackgroundPaint(Color.white);
return chart;
}
}
why cann't we cast DefaultCategoryDataset to CategoryDataset and who can I correct this ?
解决方案
The fully qualified name of CategoryDataset is org.jfree.data.category.CategoryDataset, but the cast is superfluous in this context.
Code, as tested:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.ui.ApplicationFrame;
public class BarChartDemo extends ApplicationFrame {
public BarChartDemo(final String title) {
super(title);
final CategoryDataset dataset = createDataset();
final JFreeChart chart = createChart(dataset);
final ChartPanel chartPanel = new ChartPanel(chart) {
@Override
public Dimension getPreferredSize() {
return new Dimension(500, 270);
}
};
setContentPane(chartPanel);
pack();
setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
BarChartDemo br = new BarChartDemo("title");
}
});
}
private CategoryDataset createDataset() {
// row keys...
final String series1 = "First";
final String series2 = "Second";
final String series3 = "Third";
// column keys...
final String category1 = "Category 1";
final String category2 = "Category 2";
final String category3 = "Category 3";
final String category4 = "Category 4";
final String category5 = "Category 5";
// create the dataset...
final DefaultCategoryDataset dataset = new DefaultCategoryDataset();
dataset.addValue(1.0, series1, category1);
dataset.addValue(4.0, series1, category2);
dataset.addValue(3.0, series1, category3);
dataset.addValue(5.0, series1, category4);
dataset.addValue(5.0, series1, category5);
dataset.addValue(5.0, series2, category1);
dataset.addValue(7.0, series2, category2);
dataset.addValue(6.0, series2, category3);
dataset.addValue(8.0, series2, category4);
dataset.addValue(4.0, series2, category5);
dataset.addValue(4.0, series3, category1);
dataset.addValue(3.0, series3, category2);
dataset.addValue(2.0, series3, category3);
dataset.addValue(3.0, series3, category4);
dataset.addValue(6.0, series3, category5);
return dataset;
}
private JFreeChart createChart(final CategoryDataset dataset) {
// create the chart...
final JFreeChart chart = ChartFactory.createBarChart(
"Bar Chart Demo", // chart title
"Category", // domain axis label
"Value", dataset,
PlotOrientation.VERTICAL, // orientation
true, // include legend
true, // tooltips?
false // URLs?
);
chart.setBackgroundPaint(Color.white);
return chart;
}
}
这篇关于将DefaultCategoryDataset转换为CategoryDataset的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！