列表视图中的单选按钮

Question

我正在展示一个字符串列表，使用默认的列表视图，并使用 simple_list_item_single_choice 放置了一个单选按钮。但这会将单选按钮显示在右侧，我希望将单选按钮显示在左侧。是否有可能使用默认列表视图将单选按钮显示在左侧？

- RAAAAM

Answer 1

simple_list_item_single_choice.xml使用CheckedTextView类。

这是simple_list_item_single_choice.xml文件：

 <CheckedTextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:layout_width="match_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:gravity="center_vertical"
    android:checkMark="?android:attr/listChoiceIndicatorSingle"
    android:paddingLeft="6dip"
    android:paddingRight="6dip"
   />

您需要为自己的需求创建一个自定义的xml文件，并使用CheckBox来实现您的目标。 以下是您的custom.xml：

 <CheckBox
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:layout_width="fill_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:gravity="center_vertical"
    android:button="?android:attr/listChoiceIndicatorSingle"
    android:paddingLeft="6dip"
    android:paddingRight="6dip"
   />

在你的代码中，只需使用custom.xml代替simple_list_item_single_choice.xml即可。

希望对你有所帮助。

- Tanmay Mandal

---

谢谢Tanmay，它正在工作，我把单选按钮放在了左边，但我遇到的问题是单选按钮和列表视图中的文本合并在一起。我想要将单选按钮和字符串在列表视图中分开。这可能吗..？ - RAAAAM

是的，我正在使用OnItemClickListener，但在为列表视图自定义单选按钮后，监听器将不起作用。每当我点击列表视图时，只有单选按钮会变成绿色。在列表视图上单击时不会发生任何事情。请告诉我我犯了什么错误。 - RAAAAM

抱歉，它无法工作。我在列表视图中放置了android:focusable="false"，但仍然无法工作。是否需要添加任何单选框的点击监听器？类似这样的操作？ - RAAAAM

同时，当我在列表视图中使用 simple_list_item_single_choice 时，onItemClicklistener起作用了，但是当我使用自定义的单选框时，监听器将不起作用。我犯了什么错误？请指导我。 - RAAAAM

没有错误。让我来帮你。 - Tanmay Mandal

Answer 2

simple_list_item_single_choice 使用 CheckedTextView 类。

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2008 The Android Open Source Project

     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
     You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

     Unless required by applicable law or agreed to in writing, software
     distributed under the License is distributed on an "AS IS" BASIS,
     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     See the License for the specific language governing permissions and
     limitations under the License.
-->

<CheckedTextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:layout_width="match_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:gravity="center_vertical"
    android:checkMark="?android:attr/listChoiceIndicatorSingle"
    android:paddingLeft="6dip"
    android:paddingRight="6dip"
/>

CheckedTextView类属于android.widget包。

该类的源代码如下。

/*

 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.widget;

import com.android.internal.R;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.ViewDebug;
import android.view.accessibility.AccessibilityEvent;


/**
 * An extension to TextView that supports the {@link android.widget.Checkable} interface.
 * This is useful when used in a {@link android.widget.ListView ListView} where the it's 
 * {@link android.widget.ListView#setChoiceMode(int) setChoiceMode} has been set to
 * something other than {@link android.widget.ListView#CHOICE_MODE_NONE CHOICE_MODE_NONE}.
 *
 */
public class CheckedTextView extends TextView implements Checkable {
    private boolean mChecked;
    private int mCheckMarkResource;
    private Drawable mCheckMarkDrawable;
    private int mBasePaddingRight;
    private int mCheckMarkWidth;

    private static final int[] CHECKED_STATE_SET = {
        R.attr.state_checked
    };

    public CheckedTextView(Context context) {
        this(context, null);
    }

    public CheckedTextView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CheckedTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.CheckedTextView, defStyle, 0);

        Drawable d = a.getDrawable(R.styleable.CheckedTextView_checkMark);
        if (d != null) {
            setCheckMarkDrawable(d);
        }

        boolean checked = a.getBoolean(R.styleable.CheckedTextView_checked, false);
        setChecked(checked);

        a.recycle();
    }

    public void toggle() {
        setChecked(!mChecked);
    }

    @ViewDebug.ExportedProperty
    public boolean isChecked() {
        return mChecked;
    }

    /**
     * <p>Changes the checked state of this text view.</p>
     *
     * @param checked true to check the text, false to uncheck it
     */
    public void setChecked(boolean checked) {
        if (mChecked != checked) {
            mChecked = checked;
            refreshDrawableState();
        }
    }


    /**
     * Set the checkmark to a given Drawable, identified by its resourece id. This will be drawn
     * when {@link #isChecked()} is true.
     * 
     * @param resid The Drawable to use for the checkmark.
     */
    public void setCheckMarkDrawable(int resid) {
        if (resid != 0 && resid == mCheckMarkResource) {
            return;
        }

        mCheckMarkResource = resid;

        Drawable d = null;
        if (mCheckMarkResource != 0) {
            d = getResources().getDrawable(mCheckMarkResource);
        }
        setCheckMarkDrawable(d);
    }

    /**
     * Set the checkmark to a given Drawable. This will be drawn when {@link #isChecked()} is true.
     *
     * @param d The Drawable to use for the checkmark.
     */
    public void setCheckMarkDrawable(Drawable d) {
        if (mCheckMarkDrawable != null) {
            mCheckMarkDrawable.setCallback(null);
            unscheduleDrawable(mCheckMarkDrawable);
        }
        if (d != null) {
            d.setCallback(this);
            d.setVisible(getVisibility() == VISIBLE, false);
            d.setState(CHECKED_STATE_SET);
            setMinHeight(d.getIntrinsicHeight());

            mCheckMarkWidth = d.getIntrinsicWidth();
            mPaddingRight = mCheckMarkWidth + mBasePaddingRight;
            d.setState(getDrawableState());
        } else {
            mPaddingRight = mBasePaddingRight;
        }
        mCheckMarkDrawable = d;
        requestLayout();
    }

    @Override
    public void setPadding(int left, int top, int right, int bottom) {
        super.setPadding(left, top, right, bottom);
        mBasePaddingRight = mPaddingRight;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        final Drawable checkMarkDrawable = mCheckMarkDrawable;
        if (checkMarkDrawable != null) {
            final int verticalGravity = getGravity() & Gravity.VERTICAL_GRAVITY_MASK;
            final int height = checkMarkDrawable.getIntrinsicHeight();

            int y = 0;

            switch (verticalGravity) {
                case Gravity.BOTTOM:
                    y = getHeight() - height;
                    break;
                case Gravity.CENTER_VERTICAL:
                    y = (getHeight() - height) / 2;
                    break;
            }

            int right = getWidth();
            checkMarkDrawable.setBounds(
                    right - mCheckMarkWidth - mBasePaddingRight, 
                    y, 
                    right - mBasePaddingRight, 
                    y + height);
            checkMarkDrawable.draw(canvas);
        }
    }

    @Override
    protected int[] onCreateDrawableState(int extraSpace) {
        final int[] drawableState = super.onCreateDrawableState(extraSpace + 1);
        if (isChecked()) {
            mergeDrawableStates(drawableState, CHECKED_STATE_SET);
        }
        return drawableState;
    }

    @Override
    protected void drawableStateChanged() {
        super.drawableStateChanged();

        if (mCheckMarkDrawable != null) {
            int[] myDrawableState = getDrawableState();

            // Set the state of the Drawable
            mCheckMarkDrawable.setState(myDrawableState);

            invalidate();
        }
    }

    @Override
    public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
        boolean populated = super.dispatchPopulateAccessibilityEvent(event);
        if (!populated) {
            event.setChecked(mChecked);
        }
        return populated;
    }
}

你需要修改 onDraw 和 simple_list_item_single_choice.xml。

例如：

<**your class(modifyed CheckedTextView)** xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:layout_width="match_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:gravity="center_vertical"
    android:checkMark="?android:attr/listChoiceIndicatorSingle"
    android:paddingLeft="6dip"
    android:paddingRight="6dip"
/>

- bluekyg

Answer 3

默认情况下，单选按钮在右侧是不可能的。如果您想将其放在左侧，则应该从SDK中获取simple_list_item_single_choice.xml布局的源代码并进行适当的更改，然后使用此自定义布局而不是默认布局。

- denis.solonenko