Java 为什么cardlayout键作为对象传递?
Java 为什么cardlayout键作为对象传递?,java,swing,enums,cardlayout,Java,Swing,Enums,Cardlayout,java.awt.CardLayout.addLayoutComponent(组件组件、对象约束) 来自docs.oracle的“约束指定的对象必须是字符串” 那么,如果对象必须是字符串,为什么该方法将对象作为参数?这个问题一直困扰着我,因为它让我希望有一种简单的方法可以将枚举用作cardlayout的键 public class MainWindow extends JPanel { private CardLayout cards = new CardLayout(); public M
java.awt.CardLayout.addLayoutComponent(组件组件、对象约束)
来自docs.oracle的“约束指定的对象必须是字符串”
那么,如果对象必须是字符串,为什么该方法将对象作为参数?这个问题一直困扰着我,因为它让我希望有一种简单的方法可以将枚举用作cardlayout的键
public class MainWindow extends JPanel {
private CardLayout cards = new CardLayout();
public MainWindow() {
setLayout(cards);
cards.addLayoutComponent(new FirstComp(), MyEnum.LONG_ANNOYING_NAME_ONE);
cards.addLayoutComponent(new SecondComp(), MyEnum.LONG_ANNOYING_NAME_TWO);
cards.addLayoutComponent(new ThirdComp(), MyEnum.LONG_ANNOYING_NAME_THREE);
/**
* notice no .toString() call on enums. Is there a way to define my
* enum class so that this functionality is possible?
**/
}
public void showMethod(MyEnum show) {
cards.show(this, MyEnum);
}
}
LayoutManager2定义addLayoutComponent(组件、对象)。第二个参数是Object,因为不同的布局管理器可以支持不同类型的约束。CardLayout实现LayoutManager2,因此它必须实现定义的方法。因为javadoc声明约束对象必须是字符串 但是,没有什么可以阻止您扩展CardLayout,并按照您希望的方式重新实现该方法:
public class MyCardLayout extends CardLayout {
@overrive
public void addLayoutComponent(Component comp, Object constraints) {
if (constraints != null) {
super.addLayoutComponent(comp, constraints.toString());
} else {
super.addLayoutComponent(comp, constraints);
}
}
}
public class MyCardLayout extends CardLayout {
@overrive
public void addLayoutComponent(Component comp, Object constraints) {
if (constraints != null) {
super.addLayoutComponent(comp, constraints.toString());
} else {
super.addLayoutComponent(comp, constraints);
}
}
}