在android上创建一个三态复选框

Question

我遇到了一个大问题:我想在android上制作三个状态复选框.它是带有复选框的ListView上的复选框.它应该允许用户在三种状态之间切换:

• 全部检查过
• 没人检查过
• misc检查

并且可选择在变化时保持misc状态.

如果我是对的,我应该创建CompoundButton类的子类并实现boolean mchecked的int mstate intead.然后我应该覆盖事件监听器,保存状态的函数,以及状态getter和setter.

我的问题基本上是如何实现的？如何在可绘制状态之间切换？(我已经在xml中实现了middle_state)以及如何正确实现事件处理程序？

这是我开始实施的:

public class TriStateCheckBox extends CompoundButton{
    private int state;

    public TriStateCheckBox(Context context) {
        super(context);
    }
    public static interface onCheckChangedListener{
        void onCheckChanged(TriStateCheckBox view, int state);
    }

    public void onCheckChanged(TriStateCheckBox view, int state){
        this.state = state;
    }
}

这是股票CompoundButton的代码:

/*
 * 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.os.Parcel;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.ViewDebug;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;

/**
 * <p>
 * A button with two states, checked and unchecked. When the button is pressed
 * or clicked, the state changes automatically.
 * </p>
 *
 * <p><strong>XML attributes</strong></p>
 * <p>
 * See {@link android.R.styleable#CompoundButton
 * CompoundButton Attributes}, {@link android.R.styleable#Button Button
 * Attributes}, {@link android.R.styleable#TextView TextView Attributes}, {@link
 * android.R.styleable#View View Attributes}
 * </p>
 */
public abstract class CompoundButton extends Button implements Checkable {
    private boolean mChecked;
    private int mButtonResource;
    private boolean mBroadcasting;
    private Drawable mButtonDrawable;
    private OnCheckedChangeListener mOnCheckedChangeListener;
    private OnCheckedChangeListener mOnCheckedChangeWidgetListener;

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

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

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

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

        TypedArray a =
                context.obtainStyledAttributes(
                        attrs, com.android.internal.R.styleable.CompoundButton, defStyle, 0);

        Drawable d = a.getDrawable(com.android.internal.R.styleable.CompoundButton_button);
        if (d != null) {
            setButtonDrawable(d);
        }

        boolean checked = a
                .getBoolean(com.android.internal.R.styleable.CompoundButton_checked, false);
        setChecked(checked);

        a.recycle();
    }

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

    @Override
    public boolean performClick() {
        /*
         * XXX: These are tiny, need some surrounding 'expanded touch area',
         * which will need to be implemented in Button if we only override
         * performClick()
         */

        /* When clicked, toggle the state */
        toggle();
        return super.performClick();
    }

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

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

            // Avoid infinite recursions if setChecked() is called from a listener
            if (mBroadcasting) {
                return;
            }

            mBroadcasting = true;
            if (mOnCheckedChangeListener != null) {
                mOnCheckedChangeListener.onCheckedChanged(this, mChecked);
            }
            if (mOnCheckedChangeWidgetListener != null) {
                mOnCheckedChangeWidgetListener.onCheckedChanged(this, mChecked);
            }

            mBroadcasting = false;            
        }
    }

    /**
     * Register a callback to be invoked when the checked state of this button
     * changes.
     *
     * @param listener the callback to call on checked state change
     */
    public void setOnCheckedChangeListener(OnCheckedChangeListener listener) {
        mOnCheckedChangeListener = listener;
    }

    /**
     * Register a callback to be invoked when the checked state of this button
     * changes. This callback is used for internal purpose only.
     *
     * @param listener the callback to call on checked state change
     * @hide
     */
    void setOnCheckedChangeWidgetListener(OnCheckedChangeListener listener) {
        mOnCheckedChangeWidgetListener = listener;
    }

    /**
     * Interface definition for a callback to be invoked when the checked state
     * of a compound button changed.
     */
    public static interface OnCheckedChangeListener {
        /**
         * Called when the checked state of a compound button has changed.
         *
         * @param buttonView The compound button view whose state has changed.
         * @param isChecked  The new checked state of buttonView.
         */
        void onCheckedChanged(CompoundButton buttonView, boolean isChecked);
    }

    /**
     * Set the background to a given Drawable, identified by its resource id.
     *
     * @param resid the resource id of the drawable to use as the background 
     */
    public void setButtonDrawable(int resid) {
        if (resid != 0 && resid == mButtonResource) {
            return;
        }

        mButtonResource = resid;

        Drawable d = null;
        if (mButtonResource != 0) {
            d = getResources().getDrawable(mButtonResource);
        }
        setButtonDrawable(d);
    }

    /**
     * Set the background to a given Drawable
     *
     * @param d The Drawable to use as the background
     */
    public void setButtonDrawable(Drawable d) {
        if (d != null) {
            if (mButtonDrawable != null) {
                mButtonDrawable.setCallback(null);
                unscheduleDrawable(mButtonDrawable);
            }
            d.setCallback(this);
            d.setState(getDrawableState());
            d.setVisible(getVisibility() == VISIBLE, false);
            mButtonDrawable = d;
            mButtonDrawable.setState(null);
            setMinHeight(mButtonDrawable.getIntrinsicHeight());
        }

        refreshDrawableState();
    }

    @Override
    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
        super.onInitializeAccessibilityEvent(event);
        event.setChecked(mChecked);
    }

    @Override
    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
        super.onInitializeAccessibilityNodeInfo(info);
        info.setCheckable(true);
        info.setChecked(mChecked);
    }

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

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

            int y = 0;

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

            buttonDrawable.setBounds(0, y, buttonDrawable.getIntrinsicWidth(), y + height);
            buttonDrawable.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 (mButtonDrawable != null) {
            int[] myDrawableState = getDrawableState();

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

            invalidate();
        }
    }

    @Override
    protected boolean verifyDrawable(Drawable who) {
        return super.verifyDrawable(who) || who == mButtonDrawable;
    }

    @Override
    public void jumpDrawablesToCurrentState() {
        super.jumpDrawablesToCurrentState();
        if (mButtonDrawable != null) mButtonDrawable.jumpToCurrentState();
    }

    static class SavedState extends BaseSavedState {
        boolean checked;

        /**
         * Constructor called from {@link CompoundButton#onSaveInstanceState()}
         */
        SavedState(Parcelable superState) {
            super(superState);
        }

        /**
         * Constructor called from {@link #CREATOR}
         */
        private SavedState(Parcel in) {
            super(in);
            checked = (Boolean)in.readValue(null);
        }

        @Override
        public void writeToParcel(Parcel out, int flags) {
            super.writeToParcel(out, flags);
            out.writeValue(checked);
        }

        @Override
        public String toString() {
            return "CompoundButton.SavedState{"
                    + Integer.toHexString(System.identityHashCode(this))
                    + " checked=" + checked + "}";
        }

        public static final Parcelable.Creator<SavedState> CREATOR
                = new Parcelable.Creator<SavedState>() {
            public SavedState createFromParcel(Parcel in) {
                return new SavedState(in);
            }

            public SavedState[] newArray(int size) {
                return new SavedState[size];
            }
        };
    }

    @Override
    public Parcelable onSaveInstanceState() {
        // Force our ancestor class to save its state
        setFreezesText(true);
        Parcelable superState = super.onSaveInstanceState();

        SavedState ss = new SavedState(superState);

        ss.checked = isChecked();
        return ss;
    }

    @Override
    public void onRestoreInstanceState(Parcelable state) {
        SavedState ss = (SavedState) state;

        super.onRestoreInstanceState(ss.getSuperState());
        setChecked(ss.checked);
        requestLayout();
    }
}

这是我的xml state-liste实现(工作):

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <item android:state_checked="false"
          android:state_pressed="true"
          android:drawable="@drawable/btn_check_off_pressed" /> <!-- unchecked pressed -->

    <item android:state_checked="false"
          android:state_selected="true"
          android:drawable="@drawable/btn_check_off_selected" /> <!-- unchecked selected -->

    <item android:state_checked="true"
          android:state_pressed="false"
          android:state_focused="false"
          android:drawable="@drawable/btn_check_on" /> <!-- checked -->

    <item android:state_checked="true"
          android:state_pressed="true"
          android:drawable="@drawable/btn_check_on_pressed" /> <!-- checked pressed-->

    <item android:state_checked="true"
          android:state_selected="true"
          android:drawable="@drawable/btn_check_on_selected" /> <!-- checked selected-->

    <item android:state_middle="true"
          android:state_pressed="false"
          android:state_focused="false"
          android:drawable="@drawable/btn_check_middle" /> <!-- middle -->        

    <item android:state_middle="true"
          android:state_pressed="true"
          android:drawable="@drawable/btn_check_middle_pressed" /> <!-- middle pressed-->

    <item android:state_middle="true"
          android:state_selected="true"
          android:drawable="@drawable/btn_check_middle_selected"  /> <!-- middle selected--> 

    <item android:drawable="@drawable/btn_check_off" /> <!-- unchecked -->
</selector>

这是复选框的库存xml实现:

<?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.
-->

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <!-- Enabled states -->

    <item android:state_checked="true" android:state_window_focused="false"
          android:state_enabled="true"
          android:drawable="@drawable/btn_check_on" />
    <item android:state_checked="false" android:state_window_focused="false"
          android:state_enabled="true"
          android:drawable="@drawable/btn_check_off" />

    <item android:state_checked="true" android:state_pressed="true"
          android:state_enabled="true"
          android:drawable="@drawable/btn_check_on_pressed" />
    <item android:state_checked="false" android:state_pressed="true"
          android:state_enabled="true"
          android:drawable="@drawable/btn_check_off_pressed" />

    <item android:state_checked="true" android:state_focused="true"
          android:state_enabled="true"
          android:drawable="@drawable/btn_check_on_selected" />
    <item android:state_checked="false" android:state_focused="true"
          android:state_enabled="true"
          android:drawable="@drawable/btn_check_off_selected" />

    <item android:state_checked="false"
          android:state_enabled="true"
          android:drawable="@drawable/btn_check_off" />
    <item android:state_checked="true"
          android:state_enabled="true"
          android:drawable="@drawable/btn_check_on" />


    <!-- Disabled states -->

    <item android:state_checked="true" android:state_window_focused="false"
          android:drawable="@drawable/btn_check_on_disable" />
    <item android:state_checked="false" android:state_window_focused="false"
          android:drawable="@drawable/btn_check_off_disable" />

    <item android:state_checked="true" android:state_focused="true"
          android:drawable="@drawable/btn_check_on_disable_focused" />
    <item android:state_checked="false" android:state_focused="true"
          android:drawable="@drawable/btn_check_off_disable_focused" />

    <item android:state_checked="false" android:drawable="@drawable/btn_check_off_disable" />
    <item android:state_checked="true" android:drawable="@drawable/btn_check_on_disable" />

</selector>

Answer 1

老话题,但我给出了我的解决方案:

public class CheckBoxTriStates extends CheckBox {
    static private final int UNKNOW = -1;
    static private final int UNCHECKED = 0;
    static private final int CHECKED = 1;
    private int state;

    public CheckBoxTriStates(Context context) {
        super(context);
        init();
    }

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

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

    private void init() {
        state = UNKNOW;
        updateBtn();

        setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

            // checkbox status is changed from uncheck to checked.
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                switch (state) {
                    default:
                    case UNKNOW:
                        state = UNCHECKED;
                        break;
                    case UNCHECKED:
                        state = CHECKED;
                        break;
                    case CHECKED:
                        state = UNKNOW;
                        break;
                }
                updateBtn();
            }
        });
    }

    private void updateBtn() {
        int btnDrawable = R.drawable.ic_checkbox_indeterminate_black;
        switch (state) {
            default:
            case UNKNOW:
                btnDrawable = R.drawable.ic_checkbox_indeterminate_black;
                break;
            case UNCHECKED:
                btnDrawable = R.drawable.ic_checkbox_unchecked_black;
                break;
            case CHECKED:
                btnDrawable = R.drawable.ic_checkbox_checked_black;
                break;
        }

        setButtonDrawable(btnDrawable);
    }

    public int getState() {
        return state;
    }

    public void setState(int state) {
        this.state = state;
        updateBtn();
    }
}

}

你可以在这里找到按钮资源.它完美无缺.

Answer 2

最新版本的材质库支持三种状态复选框。将其添加到 build.gradle 中：

implementation 'com.google.android.material:material:1.8.0-rc01'

之后，您可以在 xml 中设置不确定状态：

  <com.google.android.material.checkbox.MaterialCheckBox
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:checkedState="indeterminate" />

或者通过代码：

    checkbox.checkedState = when (childrenSelected) {
        0 -> MaterialCheckBox.STATE_UNCHECKED
        childrenTotal -> MaterialCheckBox.STATE_CHECKED
        else -> MaterialCheckBox.STATE_INDETERMINATE
    }

其中childrenSelected是选中的复选框的数量。您还可以根据需要自定义复选框外观，请在此处查看完整文档： https: //developer.android.com/reference/com/google/android/material/checkbox/MaterialCheckBox

Answer 3

如果您确实坚持使用每个元素都有 3 个状态的 CheckBox，那么以下方法可能会起作用，但我还没有尝试过： - 创建一个扩展 CheckBox 类的类。- 添加一个变量：int 或 byte 类型的“checkstate”。该类应该有一个布尔“isChecked”变量。- 重写 onClick 或 onCheck 方法，以便它在 3 个状态之间更改 checkstate 变量，而不是切换 isChecked 变量。- 显示时，检查“checkstate”并做一些视觉效果以显示第三个状态。- 最后，告诉我它是否有效。