Question

我在Android Studio中创建了一个自定义组件，但它没有在编辑模式下渲染，但它在我在模拟器中运行时显示。我在名为custom的模块中创建了snippetLabel.java。

public class SnippetLabel extends LinearLayout {

    TextView label;
    TextView content;

    public SnippetLabel(Context context, AttributeSet attrs) {
        super(context, attrs);

        this.setOrientation(VERTICAL);

        LayoutParams labelLayoutParams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        labelLayoutParams.setMargins(0, 0, 0, (int) context.getResources().getDimension(R.dimen.snippetabel_label) );

        LayoutParams contentLayoutParams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);


        label = new TextView(context, attrs);
        label.setTextAppearance(context, R.style.GridSystem_Forms_SnippetLabelLabel);
        addView(label, labelLayoutParams);

        content = new TextView(context, attrs);
        content.setTextAppearance(context, R.style.GridSystem_Forms_SnippetLabelContent);
        addView(content, contentLayoutParams);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.snippet_label);
        CharSequence sl = a.getString(R.styleable.snippet_label_label);
        CharSequence sc = a.getString(R.styleable.snippet_label_content);
        if (sl != null) { label.setText(sl); }
        if (sc != null) { content.setText(sc); }
        a.recycle();
    }

    public void setContentText(String s){
        content.setText(s);
    }

    public void setLabelText(String s){
        label.setText(s);
    }

    public String getContentText(){
        return (String) content.getText();
    }



}

SnippetLabel.java

<resources>
    <declare-styleable name="snippet_label">
        <attr name="label" format="string" />
        <attr name="content" format="string" />
    </declare-styleable>
</resources>

Attrs.xml

<style name="GridSystem.Forms.SnippetLabel">
    <item name="android:layout_width">0dp</item>
    <item name="android:layout_height">wrap_content</item>
</style>

<style name="GridSystem.Forms.SnippetLabelLabel">
    <item name="android:layout_width">wrap_content</item>
    <item name="android:layout_height">wrap_content</item>
    <item name="android:layout_marginBottom">@dimen/snippetabel_label</item>
    <item name="android:textStyle">bold</item>
    <item name="android:textColor">@color/SnippetLabelLabel</item>
    <item name="android:textAppearance">?android:attr/textAppearanceSmall</item>
</style>

<style name="GridSystem.Forms.SnippetLabelContent">
    <item name="android:layout_width">wrap_content</item>
    <item name="android:layout_height">wrap_content</item>
    <item name="android:textColor">@color/SnippetLabelContent</item>
    <item name="android:textAppearance">?android:attr/textAppearanceSmall</item>
</style>

style.xml

  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/currentRelativeLayout"
android:layout_width="fill_parent"
android:layout_height="fill_parent">


<ScrollView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_below="@+id/toolbar">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin">


        <LinearLayout
            android:id="@+id/linearLayoutForm"
            style="@style/GridSystem.Panel">

            <TextView
                style="@style/GridSystem.Title"
                android:text="Resultado" />

            <LinearLayout
                android:id="@+id/secao_entregue_na_grafica"
                style="@style/GridSystem.Row">

                <view
                    android:id="@+id/view"
                    class="br.gov.prodemge.comum.ui.snippets.SnippetLabel"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_weight="100" />

                <br.gov.prodemge.comum.ui.snippets.SnippetLabel
                    android:id="@+id/campo_entregue_na_grafica"
                    style="@style/GridSystem.Forms.SnippetLabel"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_weight="100"
                    app:content="#"
                    app:label="Entregue na Gráfica:" />

            </LinearLayout>

            <LinearLayout
                android:id="@+id/secao_prazo"
                style="@style/GridSystem.Row">

                <br.gov.prodemge.comum.ui.snippets.SnippetLabel
                    android:id="@+id/campo_situacao"
                    style="@style/GridSystem.Forms.SnippetLabel"
                    android:layout_weight="50"
                    app:content="#"
                    app:label="Situação:" />

                <br.gov.prodemge.comum.ui.snippets.SnippetLabel
                    android:id="@+id/campo_prazo"
                    style="@style/GridSystem.Forms.SnippetLabel"
                    android:layout_weight="50"
                    app:content="#"
                    app:label="Prazo:" />


            </LinearLayout>

            <LinearLayout
                android:id="@+id/secao_mensagem_status"
                style="@style/GridSystem.Row">

                <br.gov.prodemge.comum.ui.snippets.SnippetLabel
                    android:id="@+id/campo_mensagem_status"
                    style="@style/GridSystem.Forms.SnippetLabel"
                    android:layout_weight="100"
                    app:content="#"
                    app:label="[Mensagem de Status]:" />

            </LinearLayout>

            <LinearLayout
                android:id="@+id/secao_ar_correio"
                style="@style/GridSystem.Row">

                <br.gov.prodemge.comum.ui.snippets.SnippetLabel
                    android:id="@+id/campo_ar_correio"
                    style="@style/GridSystem.Forms.SnippetLabel"
                    android:layout_weight="100"
                    app:content="#"
                    app:label="AR Correio:" />

            </LinearLayout>

            <LinearLayout
                android:id="@+id/secao_situacao_entrega"
                style="@style/GridSystem.Row">

                <br.gov.prodemge.comum.ui.snippets.SnippetLabel
                    android:id="@+id/campo_situacao_entrega"
                    style="@style/GridSystem.Forms.SnippetLabel"
                    android:layout_weight="100"
                    app:content="#"
                    app:label="Situação da Entrega:" />

            </LinearLayout>

            <LinearLayout
                android:id="@+id/secao_motivo_rejeicao"
                style="@style/GridSystem.Row">

                <br.gov.prodemge.comum.ui.snippets.SnippetLabel
                    android:id="@+id/campo_motivo_rejeicao"
                    style="@style/GridSystem.Forms.SnippetLabel"
                    android:layout_weight="100"
                    app:content="#"
                    app:label="Motivo Rejeição:" />

            </LinearLayout>

            <LinearLayout
                android:id="@+id/secao_acao"
                style="@style/GridSystem.Row">

                <br.gov.prodemge.comum.ui.snippets.SnippetLabel
                    android:id="@+id/campo_acao"
                    style="@style/GridSystem.Forms.SnippetLabel"
                    android:layout_weight="100"
                    app:content="#"
                    app:label="Ação:" />

            </LinearLayout>

        </LinearLayout>

    </LinearLayout>

</ScrollView>

layout.xml

Answer 1

您的自定义视图类必须实现更多的构造函数，视图在预览版和设备/模拟器中的实例化方式不同。一种常见的模式是将初始化代码移动到某个方法并从construstors中调用它。见例子

public class SnippetLabel extends LinearLayout {
    public SnippetLabel(Context context) {
        super(context);
        init();
    }

    public SnippetLabel(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public SnippetLabel(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        this.setOrientation(VERTICAL);
        ...
    }
}

Answer 2

还有一点要记住，补充@Lamorak的回答：如果您的组件依赖于外部数据，例如来自服务的状态、来自共享首选项的数据等，您必须使用 try-catch 来包围您的 product.info 方法。

在设计模式下，您无法访问外部数据，因此任何阻止构造函数完成的问题，您的组件都不会显示。

自定义组件未在Android Studio的“编辑模式”中显示

2 个答案: