Android example source code file (CheckBoxPreference.java)

This example Android source code file (CheckBoxPreference.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

accessibilitymanager, android, attributeset, basesavedstate, boolean, charsequence, checkable, checkboxpreference, content, creator, object, os, override, parcelable, savedstate, textview, typedarray, ui, view, widget

The CheckBoxPreference.java Android example source code

/*
 * 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.preference;

import android.app.Service;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.res.TypedArray;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.view.View;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityManager;
import android.widget.Checkable;
import android.widget.TextView;

/**
 * A {@link Preference} that provides checkbox widget
 * functionality.
 * <p>
 * This preference will store a boolean into the SharedPreferences.
 * 
 * @attr ref android.R.styleable#CheckBoxPreference_summaryOff
 * @attr ref android.R.styleable#CheckBoxPreference_summaryOn
 * @attr ref android.R.styleable#CheckBoxPreference_disableDependentsState
 */
public class CheckBoxPreference extends Preference {

    private CharSequence mSummaryOn;
    private CharSequence mSummaryOff;
    
    private boolean mChecked;
    private boolean mSendAccessibilityEventViewClickedType;

    private AccessibilityManager mAccessibilityManager;
    
    private boolean mDisableDependentsState;
    
    public CheckBoxPreference(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        
        TypedArray a = context.obtainStyledAttributes(attrs,
                com.android.internal.R.styleable.CheckBoxPreference, defStyle, 0);
        mSummaryOn = a.getString(com.android.internal.R.styleable.CheckBoxPreference_summaryOn);
        mSummaryOff = a.getString(com.android.internal.R.styleable.CheckBoxPreference_summaryOff);
        mDisableDependentsState = a.getBoolean(
                com.android.internal.R.styleable.CheckBoxPreference_disableDependentsState, false);
        a.recycle();

        mAccessibilityManager =
            (AccessibilityManager) getContext().getSystemService(Service.ACCESSIBILITY_SERVICE);
    }

    public CheckBoxPreference(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.checkBoxPreferenceStyle);
    }

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

    @Override
    protected void onBindView(View view) {
        super.onBindView(view);

        View checkboxView = view.findViewById(com.android.internal.R.id.checkbox);
        if (checkboxView != null && checkboxView instanceof Checkable) {
            ((Checkable) checkboxView).setChecked(mChecked);

            // send an event to announce the value change of the CheckBox and is done here
            // because clicking a preference does not immediately change the checked state
            // for example when enabling the WiFi
            if (mSendAccessibilityEventViewClickedType &&
                    mAccessibilityManager.isEnabled() &&
                    checkboxView.isEnabled()) {
                mSendAccessibilityEventViewClickedType = false;

                int eventType = AccessibilityEvent.TYPE_VIEW_CLICKED;
                checkboxView.sendAccessibilityEventUnchecked(AccessibilityEvent.obtain(eventType));
            }
        }

        // Sync the summary view
        TextView summaryView = (TextView) view.findViewById(com.android.internal.R.id.summary);
        if (summaryView != null) {
            boolean useDefaultSummary = true;
            if (mChecked && mSummaryOn != null) {
                summaryView.setText(mSummaryOn);
                useDefaultSummary = false;
            } else if (!mChecked && mSummaryOff != null) {
                summaryView.setText(mSummaryOff);
                useDefaultSummary = false;
            }

            if (useDefaultSummary) {
                final CharSequence summary = getSummary();
                if (summary != null) {
                    summaryView.setText(summary);
                    useDefaultSummary = false;
                }
            }
            
            int newVisibility = View.GONE;
            if (!useDefaultSummary) {
                // Someone has written to it
                newVisibility = View.VISIBLE;
            }
            if (newVisibility != summaryView.getVisibility()) {
                summaryView.setVisibility(newVisibility);
            }
        }
    }
    
    @Override
    protected void onClick() {
        super.onClick();
        
        boolean newValue = !isChecked();
        
        // in onBindView() an AccessibilityEventViewClickedType is sent to announce the change
        // not sending
        mSendAccessibilityEventViewClickedType = true;

        if (!callChangeListener(newValue)) {
            return;
        }
        
        setChecked(newValue);
    }

    /**
     * Sets the checked state and saves it to the {@link SharedPreferences}.
     * 
     * @param checked The checked state.
     */
    public void setChecked(boolean checked) {
        if (mChecked != checked) {
            mChecked = checked;
            persistBoolean(checked);
            notifyDependencyChange(shouldDisableDependents());
            notifyChanged();
        }
    }

    /**
     * Returns the checked state.
     * 
     * @return The checked state.
     */
    public boolean isChecked() {
        return mChecked;
    }
    
    @Override
    public boolean shouldDisableDependents() {
        boolean shouldDisable = mDisableDependentsState ? mChecked : !mChecked;
        return shouldDisable || super.shouldDisableDependents();
    }

    /**
     * Sets the summary to be shown when checked.
     * 
     * @param summary The summary to be shown when checked.
     */
    public void setSummaryOn(CharSequence summary) {
        mSummaryOn = summary;
        if (isChecked()) {
            notifyChanged();
        }
    }

    /**
     * @see #setSummaryOn(CharSequence)
     * @param summaryResId The summary as a resource.
     */
    public void setSummaryOn(int summaryResId) {
        setSummaryOn(getContext().getString(summaryResId));
    }
    
    /**
     * Returns the summary to be shown when checked.
     * @return The summary.
     */
    public CharSequence getSummaryOn() {
        return mSummaryOn;
    }
    
    /**
     * Sets the summary to be shown when unchecked.
     * 
     * @param summary The summary to be shown when unchecked.
     */
    public void setSummaryOff(CharSequence summary) {
        mSummaryOff = summary;
        if (!isChecked()) {
            notifyChanged();
        }
    }

    /**
     * @see #setSummaryOff(CharSequence)
     * @param summaryResId The summary as a resource.
     */
    public void setSummaryOff(int summaryResId) {
        setSummaryOff(getContext().getString(summaryResId));
    }
    
    /**
     * Returns the summary to be shown when unchecked.
     * @return The summary.
     */
    public CharSequence getSummaryOff() {
        return mSummaryOff;
    }

    /**
     * Returns whether dependents are disabled when this preference is on ({@code true})
     * or when this preference is off ({@code false}).
     * 
     * @return Whether dependents are disabled when this preference is on ({@code true})
     *         or when this preference is off ({@code false}).
     */
    public boolean getDisableDependentsState() {
        return mDisableDependentsState;
    }

    /**
     * Sets whether dependents are disabled when this preference is on ({@code true})
     * or when this preference is off ({@code false}).
     * 
     * @param disableDependentsState The preference state that should disable dependents.
     */
    public void setDisableDependentsState(boolean disableDependentsState) {
        mDisableDependentsState = disableDependentsState;
    }

    @Override
    protected Object onGetDefaultValue(TypedArray a, int index) {
        return a.getBoolean(index, false);
    }

    @Override
    protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
        setChecked(restoreValue ? getPersistedBoolean(mChecked)
                : (Boolean) defaultValue);
    }

    @Override
    protected Parcelable onSaveInstanceState() {
        final Parcelable superState = super.onSaveInstanceState();
        if (isPersistent()) {
            // No need to save instance state since it's persistent
            return superState;
        }
        
        final SavedState myState = new SavedState(superState);
        myState.checked = isChecked();
        return myState;
    }

    @Override
    protected void onRestoreInstanceState(Parcelable state) {
        if (state == null || !state.getClass().equals(SavedState.class)) {
            // Didn't save state for us in onSaveInstanceState
            super.onRestoreInstanceState(state);
            return;
        }
         
        SavedState myState = (SavedState) state;
        super.onRestoreInstanceState(myState.getSuperState());
        setChecked(myState.checked);
    }
    
    private static class SavedState extends BaseSavedState {
        boolean checked;
        
        public SavedState(Parcel source) {
            super(source);
            checked = source.readInt() == 1;
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            super.writeToParcel(dest, flags);
            dest.writeInt(checked ? 1 : 0);
        }

        public SavedState(Parcelable superState) {
            super(superState);
        }

        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];
            }
        };
    }
    
}