001/* 002 * Copyright (C) 2009 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.io; 016 017import com.google.common.annotations.GwtIncompatible; 018import com.google.common.annotations.J2ktIncompatible; 019import com.google.errorprone.annotations.CanIgnoreReturnValue; 020import java.io.IOException; 021import org.checkerframework.checker.nullness.qual.Nullable; 022 023/** 024 * A callback to be used with the streaming {@code readLines} methods. 025 * 026 * <p>{@link #processLine} will be called for each line that is read, and should return {@code 027 * false} when you want to stop processing. 028 * 029 * @author Miles Barr 030 * @since 1.0 031 */ 032@J2ktIncompatible 033@GwtIncompatible 034@ElementTypesAreNonnullByDefault 035public interface LineProcessor<T extends @Nullable Object> { 036 037 /** 038 * This method will be called once for each line. 039 * 040 * @param line the line read from the input, without delimiter 041 * @return true to continue processing, false to stop 042 */ 043 @CanIgnoreReturnValue // some uses know that their processor never returns false 044 boolean processLine(String line) throws IOException; 045 046 /** Return the result of processing all the lines. */ 047 @ParametricNullness 048 T getResult(); 049}