如何仅在输入 2 个字符后才在 GWT SuggestBox 中显示建议？

Question

我正在尝试制作一个仅在输入 2 个字符后才显示建议的 SuggestBox。我的想法是在文本长度为 1 时隐藏建议，使用 class DefaultSuggestionDisplay。我尝试在 SuggestionBox 本身及其 TextBox 上附加不同的处理程序，如 KeyPressHandler 和 KeyUpHandler，但其中 none 似乎有效。你有 "suggestions" 吗？ :D

Answer 1

您可以扩展 SuggestBox 并覆盖 showSuggestionList() 方法。

添加 KeyUpHandler 不起作用，因为您添加了另一个 KeyUpHandler，而不是替换 SuggestBox 添加到它自己的 TextBox 的那个。

编辑：

@Override
showSuggestionList() {
    if (getTextBox().getValue().length() > 1) {
        super.showSuggestionList();
    }
}

Answer 2

您可以扩展 DefaultSuggestionDisplay 并覆盖 showSuggestions 方法：

public class MySuggestionDisplay extends DefaultSuggestionDisplay {
    @Override
    protected void showSuggestions(SuggestBox suggestBox, Collection<? extends Suggestion> suggestions, boolean isDisplayStringHTML, boolean isAutoSelectEnabled, SuggestionCallback callback) {
        if(suggestBox.getText().length() > 1)
            super.showSuggestions(suggestBox, suggestions, isDisplayStringHTML, isAutoSelectEnabled, callback);
    }
}

您必须将新显示传递给 SuggestBox 构造函数：

public class MySuggestBox extends SuggestBox {
    public MySuggestBox() {
        super(
            new MySuggestOracle(),
            new TextBox(), 
            new MySuggestionDisplay());
    }
}

在此构造函数中，您应该提供：

你自己的 SuggestOracle class（此处命名为 MySuggestOracle）- 我想你有一个
TextBox - 它是默认的输入文本的小部件（你可以提供自己的，它只需要实现 HasText）
SuggestionDisplay - 使用覆盖了 showSuggestions 方法的方法。

这是完整的工作示例代码，显示了至少输入 2 个字符的建议：

import java.util.ArrayList;
import java.util.Collection;

import com.google.gwt.user.client.ui.SuggestBox;
import com.google.gwt.user.client.ui.SuggestOracle;
import com.google.gwt.user.client.ui.SuggestOracle.Suggestion;
import com.google.gwt.user.client.ui.TextBox;

public class MySuggestBox extends SuggestBox {

    public MySuggestBox() {
        super(
            new SuggestOracle() {
                @Override
                public void requestSuggestions(Request request, Callback callback) {
                    ArrayList<Suggestion> suggestions = new ArrayList<Suggestion>();
                    suggestions.add(new MySuggestion("aaa"));
                    suggestions.add(new MySuggestion("bbb"));
                    suggestions.add(new MySuggestion("ccc"));
                    suggestions.add(new MySuggestion("ddd"));

                    Response response = new Response();
                    response.setSuggestions(suggestions);
                    callback.onSuggestionsReady(request, response);
                }
            }, 
            new TextBox(), 
            new MySuggestionDisplay());
    }

    public static class MySuggestionDisplay extends DefaultSuggestionDisplay {
        @Override
        protected void showSuggestions(SuggestBox suggestBox, Collection<? extends Suggestion> suggestions, boolean isDisplayStringHTML, boolean isAutoSelectEnabled, SuggestionCallback callback) {
            if(suggestBox.getText().length() > 1)
                super.showSuggestions(suggestBox, suggestions, isDisplayStringHTML, isAutoSelectEnabled, callback);
        }
    }

    public static class MySuggestion implements Suggestion {

        private String text;

        public MySuggestion(String text) {
            this.text = text;
        }

        @Override
        public String getDisplayString() {
            return text;
        }

        @Override
        public String getReplacementString() {
            return text;
        }
    }
}

如何仅在输入 2 个字符后才在 GWT SuggestBox 中显示建议？

How to show suggestions in a GWT SuggestBox only after 2 characters have been typed?

gwt

suggestbox