Question

private void jComboBox1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
        // TODO add your handling code here:

        //9


        txtTot.setText(jComboBox1.getSelectedItem().toString());
        tot= Double.parseDouble(txtTot.getText());
        CMB= (Double)jComboBox1.getSelectedItem();
        Total2=tot+CMB;
        txtTot.setText(Double.toString(Total2));

    }

从ComboBox我设置jtextfield，第二行我从string获取textfield并尝试将其转换为{double 1}}。

以下错误：

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
    at test.Test.jComboBox1ActionPerformed(Test.java:392)
    at test.Test.access$600(Test.java:18)
    at test.Test$7.actionPerformed(Test.java:134)
    at javax.swing.JComboBox.fireActionEvent(JComboBox.java:1258)
    at javax.swing.JComboBox.setSelectedItem(JComboBox.java:586)
    at javax.swing.JComboBox.setSelectedIndex(JComboBox.java:622)

Answer 1

对我而言，似乎您正在从组合框中选择一个值，然后尝试将它们组合在一起以创建一个总计，每次从组合框中选择一个新值时都会更新总数。

这似乎对我有用，注意我已经走了第一线，因为它干扰了现有的总数。

tot= Double.parseDouble(txtTot.getText());
CMB = Double.parseDouble((String) jComboBox1.getSelectedItem());
Total2=tot+CMB;
txtTot.setText(Double.toString(Total2));

Answer 2

尝试将txtTot.getText（）打印到控制台并检查它是否采用正确的十进制格式。格式错误可能是错误的原因。

将字符串转换为Double - JAVA

2 个答案: