字符串无法转换为 java 错误：尝试将字符串转换为整数
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String cannot be cast to java error: Trying to convert string into integer
提问by user3250995
When trying to add years from a combobox this error shows:
尝试从组合框中添加年份时，此错误显示：
Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
线程“AWT-EventQueue-0”中的异常 java.lang.ClassCastException：java.lang.String 无法转换为 java.lang.Integer
at LibraryFrame$addListener.actionPerformed(LibraryFrame.java:103)
在 LibraryFrame$addListener.actionPerformed(LibraryFrame.java:103)
The program highlights the 'Integer anInteger = (Integer) selected;' line as the problem?
程序高亮显示'Integer anInteger = (Integer) selected;' 线路问题？
class addListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
Object selected = yearCombo.getSelectedItem();
if(e.getSource() == button)
{
System.out.println("Add button clicked!");
String t = title.getText();
Integer anInteger = (Integer) selected;
int y = anInteger;
int q = Integer.parseInt(quantity.getText());
library.addItem(new LibraryItem(t,y,q));
library.printLibrary();
System.out.println("Thank You!");
}
}
}
Heres the code where yearCombo is populated:
这是填充 yearCombo 的代码：
label1 = new JLabel("Year");
yearCombo = new JComboBox();
ArrayList<Integer> countYear = new ArrayList<Integer>();
for(int y=1800; y<=2014; y++)
{
countYear.add(y);
}
for(int x=0; x < countYear.size(); x++)
{
yearCombo.addItem((countYear.get(x) + " "));
}
CODE NOW THROWING A NUMBER FORMAT EXCEPTION after changing
代码现在在更改后抛出数字格式异常
Integer anInteger = (Integer) selected;
to
到
Integer anInteger = Integer.parseInt(selected.toString());
采纳答案by Ingo
This:
这个：
yearCombo.addItem((countYear.get(x) + " "));
// ^--------------- not numeric
results in a string that cannot be converted to a number, no matter what countYear.get(x)gives you.
导致无法转换为数字的字符串，无论countYear.get(x)给您什么。
Do you really need to add that space there?
你真的需要在那里添加那个空间吗？
回答by Dima
change
改变
Integer anInteger = (Integer) selected;
to
到
Integer anInteger = Integer.parseInt(selected.toString());
as the error says, String and integer are completely different classes,
正如错误所说，字符串和整数是完全不同的类，
you can't cast String to Integer as you can't use television as a car.
您不能将 String 转换为 Integer，因为您不能将电视用作汽车。
edit:
编辑：
NumberFormatExceptionmeans that the object selectedis not a number. if you have a string like "hello", what do you expect it to be as an integer?
NumberFormatException表示对象selected不是数字。如果你有一个像 的字符串"hello"，你希望它是一个整数吗？
