Java tutorial
package android.support.v4.preference; import android.content.Context; import android.content.DialogInterface; import android.content.res.TypedArray; import android.os.Parcel; import android.os.Parcelable; import android.support.v7.app.AlertDialog; import android.text.TextUtils; import android.util.AttributeSet; import com.s16.dhammadroid.R; /** * Created by SMM on 11/3/2016. */ public class ListPreference extends DialogPreference { private static int[] ATTRS = new int[] { android.R.attr.entries, android.R.attr.entryValues, android.R.attr.summary }; private CharSequence[] mEntries; private CharSequence[] mEntryValues; private String mValue; private String mSummary; private int mClickedDialogEntryIndex; private boolean mValueSet; public ListPreference(Context context) { super(context); initialize(context, null, R.attr.listPreferenceStyle, 0); } public ListPreference(Context context, AttributeSet attrs) { super(context, attrs); initialize(context, attrs, R.attr.listPreferenceStyle, 0); } public ListPreference(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); initialize(context, attrs, defStyleAttr, 0); } public ListPreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr); initialize(context, attrs, defStyleAttr, defStyleRes); } private void initialize(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { final TypedArray a = context.obtainStyledAttributes(attrs, ATTRS); mEntries = a.getTextArray(0); mEntryValues = a.getTextArray(1); mSummary = a.getString(2); a.recycle(); } /** * Sets the human-readable entries to be shown in the list. This will be * shown in subsequent dialogs. * <p> * Each entry must have a corresponding index in * {@link #setEntryValues(CharSequence[])}. * * @param entries The entries. * @see #setEntryValues(CharSequence[]) */ public void setEntries(CharSequence[] entries) { mEntries = entries; } /** * @see #setEntries(CharSequence[]) * @param entriesResId The entries array as a resource. */ public void setEntries(int entriesResId) { setEntries(getContext().getResources().getTextArray(entriesResId)); } /** * The list of entries to be shown in the list in subsequent dialogs. * * @return The list as an array. */ public CharSequence[] getEntries() { return mEntries; } /** * The array to find the value to save for a preference when an entry from * entries is selected. If a user clicks on the second item in entries, the * second item in this array will be saved to the preference. * * @param entryValues The array to be used as values to save for the preference. */ public void setEntryValues(CharSequence[] entryValues) { mEntryValues = entryValues; } /** * @see #setEntryValues(CharSequence[]) * @param entryValuesResId The entry values array as a resource. */ public void setEntryValues(int entryValuesResId) { setEntryValues(getContext().getResources().getTextArray(entryValuesResId)); } /** * Returns the array of values to be saved for the preference. * * @return The array of values. */ public CharSequence[] getEntryValues() { return mEntryValues; } /** * Sets the value of the key. This should be one of the entries in * {@link #getEntryValues()}. * * @param value The value to set for the key. */ public void setValue(String value) { // Always persist/notify the first time. final boolean changed = !TextUtils.equals(mValue, value); if (changed || !mValueSet) { mValue = value; mValueSet = true; persistString(value); if (changed) { notifyChanged(); } } } /** * Returns the summary of this ListPreference. If the summary * has a {@linkplain java.lang.String#format String formatting} * marker in it (i.e. "%s" or "%1$s"), then the current entry * value will be substituted in its place. * * @return the summary with appropriate string substitution */ @Override public CharSequence getSummary() { final CharSequence entry = getEntry(); if (mSummary == null || entry == null) { return super.getSummary(); } else { return String.format(mSummary, entry); } } /** * Sets the summary for this Preference with a CharSequence. * If the summary has a * {@linkplain java.lang.String#format String formatting} * marker in it (i.e. "%s" or "%1$s"), then the current entry * value will be substituted in its place when it's retrieved. * * @param summary The summary for the preference. */ @Override public void setSummary(CharSequence summary) { super.setSummary(summary); if (summary == null && mSummary != null) { mSummary = null; } else if (summary != null && !summary.equals(mSummary)) { mSummary = summary.toString(); } } /** * Sets the value to the given index from the entry values. * * @param index The index of the value to set. */ public void setValueIndex(int index) { if (mEntryValues != null) { setValue(mEntryValues[index].toString()); } } /** * Returns the value of the key. This should be one of the entries in * {@link #getEntryValues()}. * * @return The value of the key. */ public String getValue() { return mValue; } /** * Returns the entry corresponding to the current value. * * @return The entry corresponding to the current value, or null. */ public CharSequence getEntry() { int index = getValueIndex(); return index >= 0 && mEntries != null ? mEntries[index] : null; } /** * Returns the index of the given value (in the entry values array). * * @param value The value whose index should be returned. * @return The index of the value, or -1 if not found. */ public int findIndexOfValue(String value) { if (value != null && mEntryValues != null) { for (int i = mEntryValues.length - 1; i >= 0; i--) { if (mEntryValues[i].equals(value)) { return i; } } } return -1; } private int getValueIndex() { return findIndexOfValue(mValue); } @Override protected void onPrepareDialogBuilder(AlertDialog.Builder builder) { super.onPrepareDialogBuilder(builder); if (mEntries == null || mEntryValues == null) { throw new IllegalStateException("ListPreference requires an entries array and an entryValues array."); } mClickedDialogEntryIndex = getValueIndex(); builder.setSingleChoiceItems(mEntries, mClickedDialogEntryIndex, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { mClickedDialogEntryIndex = which; /* * Clicking on an item simulates the positive button * click, and dismisses the dialog. */ ListPreference.this.onClick(dialog, DialogInterface.BUTTON_POSITIVE); dialog.dismiss(); } }); /* * The typical interaction for list-based dialogs is to have * click-on-an-item dismiss the dialog instead of the user having to * press 'Ok'. */ builder.setPositiveButton(null, null); } @Override protected void onDialogClosed(boolean positiveResult) { super.onDialogClosed(positiveResult); if (positiveResult && mClickedDialogEntryIndex >= 0 && mEntryValues != null) { String value = mEntryValues[mClickedDialogEntryIndex].toString(); if (callChangeListener(value)) { setValue(value); } } } @Override protected Object onGetDefaultValue(TypedArray a, int index) { return a.getString(index); } @Override protected void onSetInitialValue(boolean restoreValue, Object defaultValue) { setValue(restoreValue ? getPersistedString(mValue) : (String) 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.value = getValue(); 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()); setValue(myState.value); } private static class SavedState extends BaseSavedState { String value; public SavedState(Parcel source) { super(source); value = source.readString(); } @Override public void writeToParcel(Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeString(value); } 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]; } }; } }