core/java/android/content/LocusId.java

/*
 * Copyright (C) 2019 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.content;

import android.annotation.NonNull;
import android.net.Uri;
import android.os.Parcel;
import android.os.Parcelable;

import com.android.internal.util.Preconditions;

import java.io.PrintWriter;

/**
 * Identifier for an unique state in the application.
 *
 * <p>Should be stable across reboots and backup / restore.
 *
 * <p>For example, a chat app could use the context to resume a conversation between 2 users.
 */
// TODO(b/123577059): make sure this is well documented and understandable
public final class LocusId implements Parcelable {

    private final Uri mUri;

    /**
     * Default constructor.
     */
    public LocusId(@NonNull Uri uri) {
        mUri = Preconditions.checkNotNull(uri);
    }

    /**
     * Gets the {@code uri} associated with the locus.
     */
    @NonNull
    public Uri getUri() {
        return mUri;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((mUri == null) ? 0 : mUri.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;
        final LocusId other = (LocusId) obj;
        if (mUri == null) {
            if (other.mUri != null) return false;
        } else {
            if (!mUri.equals(other.mUri)) return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "LocusId[uri=" + getSanitizedUri() + "]";
    }

    /** @hide */
    public void dump(@NonNull PrintWriter pw) {
        pw.print("uri:"); pw.println(getSanitizedUri());
    }

    private String getSanitizedUri() {
        final int size = mUri.toString().length();
        return size + "_chars";
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeParcelable(mUri, flags);
    }

    public static final Parcelable.Creator<LocusId> CREATOR =
            new Parcelable.Creator<LocusId>() {

        @Override
        public LocusId createFromParcel(Parcel source) {
            final Uri uri = source.readParcelable(null);
            return new LocusId(uri);
        }

        @Override
        public LocusId[] newArray(int size) {
            return new LocusId[size];
        }
    };
}