ObservableDefer.java

/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * 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 io.reactivex.internal.operators.observable;

import io.reactivex.internal.functions.ObjectHelper;
import java.util.concurrent.Callable;

import io.reactivex.*;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.internal.disposables.EmptyDisposable;

public final class ObservableDefer<T> extends Observable<T> {
    final Callable<? extends ObservableSource<? extends T>> supplier;
    public ObservableDefer(Callable<? extends ObservableSource<? extends T>> supplier) {
        this.supplier = supplier;
    }

    @Override
    public void subscribeActual(Observer<? super T> observer) {
        ObservableSource<? extends T> pub;
        try {
            pub = ObjectHelper.requireNonNull(supplier.call(), "null ObservableSource supplied");
        } catch (Throwable t) {
            Exceptions.throwIfFatal(t);
            EmptyDisposable.error(t, observer);
            return;
        }

        pub.subscribe(observer);
    }
}