如何在 SWT table 列中设置科学值(EX 123E45、143E-1,...)?
How to set scientific value(EX 123E45, 143E-1,...) in the SWT table column?
如何在SWTtable专栏取科学价值? java 科学计数法支持哪种数据类型?这该怎么做?这是我想申请科学记数法的 SWT table 的简单代码。
package test;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Date;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;
import org.eclipse.swt.widgets.TableItem;
public class SortTable {
private TableRow rows[] = new TableRow[] {
new TableRow(1, "aaa", new Date(1363784269000 L)),
new TableRow(2, "abc", new Date(1367784269000 L)),
new TableRow(3, "efc", new Date(1363584269000 L)),
new TableRow(4, "ccc", new Date(1363734269000 L)),
};
private Table table;
private TableColumn intColumn;
private TableColumn strColumn;
private TableColumn dateColumn;
private TableColumn scientificColumn;
public SortTable() {
Display display = new Display();
Shell shell = new Shell(display);
shell.setLayout(new FillLayout());
table = new Table(shell, SWT.BORDER);
table.setHeaderVisible(true);
intColumn = new TableColumn(table, SWT.NONE);
intColumn.setText("int");
intColumn.setWidth(50);
strColumn = new TableColumn(table, SWT.NONE);
strColumn.setText("string");
strColumn.setWidth(50);
dateColumn = new TableColumn(table, SWT.NONE);
dateColumn.setText("date");
dateColumn.setWidth(100);
scientificColumn = new TableColumn(table, SWT.NONE);
scientificColumn.setText("ScintificValue");
updateTable();
Listener sortListener = new Listener() {
public void handleEvent(Event e) {
TableColumn column = (TableColumn) e.widget;
if (column == intColumn) Arrays.sort(rows, BY_VAL);
if (column == strColumn) Arrays.sort(rows, BY_STR);
if (column == dateColumn) Arrays.sort(rows, BY_DATE);
table.setSortColumn(column);
updateTable();
}
};
intColumn.addListener(SWT.Selection, sortListener);
strColumn.addListener(SWT.Selection, sortListener);
dateColumn.addListener(SWT.Selection, sortListener);
shell.setSize(shell.computeSize(SWT.DEFAULT, SWT.DEFAULT).x, 300);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}
private void updateTable() {
table.removeAll();
for (TableRow row: rows) {
TableItem item = new TableItem(table, SWT.NONE);
item.setText(row.asString());
}
}
public final Comparator < TableRow > BY_VAL = new Comparator < TableRow > () {
@Override
public int compare(TableRow o1, TableRow o2) {
if (o1.val < o2.val) return -1;
if (o1.val > o2.val) return 1;
return 0;
}
};
public final Comparator < TableRow > BY_STR = new Comparator < TableRow > () {
@Override
public int compare(TableRow o1, TableRow o2) {
return o1.str.compareTo(o2.str);
}
};
public final Comparator < TableRow > BY_DATE = new Comparator < TableRow > () {
@Override
public int compare(TableRow o1, TableRow o2) {
return o1.date.compareTo(o2.date);
}
};
private class TableRow {
private int val;
private String str;
private Date date;
private SimpleDateFormat format = new SimpleDateFormat();
public TableRow(int val, String str, Date date) {
this.val = val;
this.str = str;
this.date = date;
}
public String[] asString() {
return new String[] {
Integer.toString(val), str, format.format(date)
};
}
}
public static void main(String[] args) {
new SortTable();
}
}
这与仅显示您提供的字符串的 SWT Table 无关。
这就是在 asString
方法中将值转换为字符串的方式。
对于 123e45 这样的值,integer
不适合,因为它不能容纳这么大的值,您需要使用 double
。
如果你有
double val;
您可以使用以下格式将其格式化为科学记数法:
String.format("%.3E", val)
其中“%.3E”指定小数点后 3 位的科学计数法。
有关格式字符串的更多详细信息,请参阅 this question。
如何在SWTtable专栏取科学价值? java 科学计数法支持哪种数据类型?这该怎么做?这是我想申请科学记数法的 SWT table 的简单代码。
package test;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Date;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;
import org.eclipse.swt.widgets.TableItem;
public class SortTable {
private TableRow rows[] = new TableRow[] {
new TableRow(1, "aaa", new Date(1363784269000 L)),
new TableRow(2, "abc", new Date(1367784269000 L)),
new TableRow(3, "efc", new Date(1363584269000 L)),
new TableRow(4, "ccc", new Date(1363734269000 L)),
};
private Table table;
private TableColumn intColumn;
private TableColumn strColumn;
private TableColumn dateColumn;
private TableColumn scientificColumn;
public SortTable() {
Display display = new Display();
Shell shell = new Shell(display);
shell.setLayout(new FillLayout());
table = new Table(shell, SWT.BORDER);
table.setHeaderVisible(true);
intColumn = new TableColumn(table, SWT.NONE);
intColumn.setText("int");
intColumn.setWidth(50);
strColumn = new TableColumn(table, SWT.NONE);
strColumn.setText("string");
strColumn.setWidth(50);
dateColumn = new TableColumn(table, SWT.NONE);
dateColumn.setText("date");
dateColumn.setWidth(100);
scientificColumn = new TableColumn(table, SWT.NONE);
scientificColumn.setText("ScintificValue");
updateTable();
Listener sortListener = new Listener() {
public void handleEvent(Event e) {
TableColumn column = (TableColumn) e.widget;
if (column == intColumn) Arrays.sort(rows, BY_VAL);
if (column == strColumn) Arrays.sort(rows, BY_STR);
if (column == dateColumn) Arrays.sort(rows, BY_DATE);
table.setSortColumn(column);
updateTable();
}
};
intColumn.addListener(SWT.Selection, sortListener);
strColumn.addListener(SWT.Selection, sortListener);
dateColumn.addListener(SWT.Selection, sortListener);
shell.setSize(shell.computeSize(SWT.DEFAULT, SWT.DEFAULT).x, 300);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}
private void updateTable() {
table.removeAll();
for (TableRow row: rows) {
TableItem item = new TableItem(table, SWT.NONE);
item.setText(row.asString());
}
}
public final Comparator < TableRow > BY_VAL = new Comparator < TableRow > () {
@Override
public int compare(TableRow o1, TableRow o2) {
if (o1.val < o2.val) return -1;
if (o1.val > o2.val) return 1;
return 0;
}
};
public final Comparator < TableRow > BY_STR = new Comparator < TableRow > () {
@Override
public int compare(TableRow o1, TableRow o2) {
return o1.str.compareTo(o2.str);
}
};
public final Comparator < TableRow > BY_DATE = new Comparator < TableRow > () {
@Override
public int compare(TableRow o1, TableRow o2) {
return o1.date.compareTo(o2.date);
}
};
private class TableRow {
private int val;
private String str;
private Date date;
private SimpleDateFormat format = new SimpleDateFormat();
public TableRow(int val, String str, Date date) {
this.val = val;
this.str = str;
this.date = date;
}
public String[] asString() {
return new String[] {
Integer.toString(val), str, format.format(date)
};
}
}
public static void main(String[] args) {
new SortTable();
}
}
这与仅显示您提供的字符串的 SWT Table 无关。
这就是在 asString
方法中将值转换为字符串的方式。
对于 123e45 这样的值,integer
不适合,因为它不能容纳这么大的值,您需要使用 double
。
如果你有
double val;
您可以使用以下格式将其格式化为科学记数法:
String.format("%.3E", val)
其中“%.3E”指定小数点后 3 位的科学计数法。
有关格式字符串的更多详细信息,请参阅 this question。