Java tutorial
/* * Copyright (C) 2010 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.annotation.StringRes; import android.annotation.UnsupportedAppUsage; import android.content.Context; import android.content.SharedPreferences; import android.content.res.TypedArray; import android.os.Parcel; import android.os.Parcelable; import android.text.TextUtils; import android.util.AttributeSet; import android.view.View; import android.widget.TextView; /** * Common base class for preferences that have two selectable states, persist a * boolean value in SharedPreferences, and may have dependent preferences that are * enabled/disabled based on the current state. */ public abstract class TwoStatePreference extends Preference { private CharSequence mSummaryOn; private CharSequence mSummaryOff; boolean mChecked; private boolean mCheckedSet; private boolean mDisableDependentsState; public TwoStatePreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); } public TwoStatePreference(Context context, AttributeSet attrs, int defStyleAttr) { this(context, attrs, defStyleAttr, 0); } public TwoStatePreference(Context context, AttributeSet attrs) { this(context, attrs, 0); } public TwoStatePreference(Context context) { this(context, null); } @Override protected void onClick() { super.onClick(); final boolean newValue = !isChecked(); if (callChangeListener(newValue)) { setChecked(newValue); } } /** * Sets the checked state and saves it to the {@link SharedPreferences}. * * @param checked The checked state. */ public void setChecked(boolean checked) { // Always persist/notify the first time; don't assume the field's default of false. final boolean changed = mChecked != checked; if (changed || !mCheckedSet) { mChecked = checked; mCheckedSet = true; persistBoolean(checked); if (changed) { 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(@StringRes 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(@StringRes 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); } /** * Sync a summary view contained within view's subhierarchy with the correct summary text. * @param view View where a summary should be located */ @UnsupportedAppUsage void syncSummaryView(View view) { // Sync the summary view TextView summaryView = (TextView) view.findViewById(com.android.internal.R.id.summary); if (summaryView != null) { boolean useDefaultSummary = true; if (mChecked && !TextUtils.isEmpty(mSummaryOn)) { summaryView.setText(mSummaryOn); useDefaultSummary = false; } else if (!mChecked && !TextUtils.isEmpty(mSummaryOff)) { summaryView.setText(mSummaryOff); useDefaultSummary = false; } if (useDefaultSummary) { final CharSequence summary = getSummary(); if (!TextUtils.isEmpty(summary)) { 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 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); } 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]; } }; } }