java - 错误 : unchecked call to DefaultComboBoxModel(E[])

当我构建/运行由 NetBeans Applet Form 制作的小程序时，出现 2 个错误:

warning: [unchecked] unchecked call to DefaultComboBoxModel(E[]) as a member of the raw type DefaultComboBoxModel
        levelBox.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "1", "2", "3", "4", "5", "6", "7" }));
  where E is a type-variable:
    E extends Object declared in class DefaultComboBoxModel
warning: [unchecked] unchecked call to setModel(ComboBoxModel<E>) as a member of the raw type JComboBox
        levelBox.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "1", "2", "3", "4", "5", "6", "7" }));
  where E is a type-variable:
    E extends Object declared in class JComboBox
2 warnings

如果我点击下拉菜单，我会在它旁边看到一个感叹号。这是为什么？

此外，这与“-Xlint:unchecked”选项有关。

最佳答案

new javax.swing.DefaultComboBoxModel(new String[]

应该替换为

new javax.swing.DefaultComboBoxModel<String>(new String[]

该警告也可以忽略。