Java将Map大小与ObjectProperty绑定< Integer>

brccelvz 于 2023-03-11 发布在 Java

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我有一个UI元素，需要在Map更新时更新。我想将Map大小与ObjectProperty绑定，但.bind()方法不允许。如何将属性与Map大小绑定？代码示例：

public class ContainerOJ {

    protected final ObjectProperty<Integer> objCount;
    protected Map<String, String> stackMap;

    public ContainerOJ() {
        this.objCount = new SimpleObjectProperty<>(0);
        this.stackMap = new HashMap<>();

//        objCount.bind(stackMap.size());
    }

    public void addToStack(String newObj) {
        if (stackMap.get(newObj) != null) {
            /* Obj:{}, already exists in the Stack:{} */
            return;
        }

        stackMap.put(newObj, newObj);
        objCount.set(stackMap.size());
    }

    public Integer getObjCount() {
        return objCount.get();
    }

    public ObjectProperty<Integer> objCountProperty() {
        return objCount;
    }
}

Java

来源：https://stackoverflow.com/questions/75695568/java-bind-map-size-with-objectpropertyinteger

1条答案

按热度按时间

cgh8pdjw1#

不应使用ObjectProperty<Integer>。请改用ReadOnlyIntegerWrapper和ReadOnlyIntegerProperty：

protected final ReadOnlyIntegerWrapper objCount;

public ContainerOJ() {
    this.objCount = new ReadOnlyIntegerWrapper();
    this.stackMap = new HashMap<>();
}

//...

public int getObjCount() {
    return objCount.get();
}

public ReadOnlyIntegerProperty objCountProperty() {
    return objCount.getReadOnlyProperty();
}

实际上，您可以使用ObservableMap来简化此操作：

protected final ReadOnlyIntegerWrapper objCount;
protected final ObservableMap<String, String> stackMap;

public ContainerOJ() {
    this.objCount = new ReadOnlyIntegerWrapper();
    this.stackMap = FXCollections.observableHashMap();

    objCount.bind(Bindings.size(stackMap));
}

public void addToStack(String newObj) {
    stackMap.putIfAbsent(newObj, newObj);
}

public int getObjCount() {
    return objCount.get();
}

public ReadOnlyIntegerProperty objCountProperty() {
    return objCount.getReadOnlyProperty();
}

我不知道为什么你要在这里使用Map，因为你的键和值是一样的，看起来你应该使用Set，更具体地说，ObservableSet：

protected final ReadOnlyIntegerWrapper objCount;
protected final ObservableSet<String> stackMap;

public ContainerOJ() {
    this.objCount = new ReadOnlyIntegerWrapper();
    this.stackMap = FXCollections.observableSet();

    objCount.bind(Bindings.size(stackMap));
}

public void addToStack(String newObj) {
    stackMap.add(newObj);
}

public int getObjCount() {
    return objCount.get();
}

public ReadOnlyIntegerProperty objCountProperty() {
    return objCount.getReadOnlyProperty();
}

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Java将Map大小与ObjectProperty绑定< Integer>

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