StringUtil.java

/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you 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.netty.util.internal;

import java.util.ArrayList;
import java.util.Formatter;
import java.util.List;

/**
 * String utility class.
 */
public final class StringUtil {

    private StringUtil() {
        // Unused.
    }

    public static final String NEWLINE;

    static {
        String newLine;

        try {
            newLine = new Formatter().format("%n").toString();
        } catch (Exception e) {
            // Should not reach here, but just in case.
            newLine = "\n";
        }

        NEWLINE = newLine;
    }

    private static final String EMPTY_STRING = "";

    /**
     * Splits the specified {@link String} with the specified delimiter.  This operation is a simplified and optimized
     * version of {@link String#split(String)}.
     */
    public static String[] split(String value, char delim) {
        final int end = value.length();
        final List<String> res = new ArrayList<String>();

        int start = 0;
        for (int i = 0; i < end; i ++) {
            if (value.charAt(i) == delim) {
                if (start == i) {
                    res.add(EMPTY_STRING);
                } else {
                    res.add(value.substring(start, i));
                }
                start = i + 1;
            }
        }

        if (start == 0) { // If no delimiter was found in the value
            res.add(value);
        } else {
            if (start != end) {
                // Add the last element if it's not empty.
                res.add(value.substring(start, end));
            } else {
                // Truncate trailing empty elements.
                for (int i = res.size() - 1; i >= 0; i --) {
                    if (res.get(i).isEmpty()) {
                        res.remove(i);
                    } else {
                        break;
                    }
                }
            }
        }

        return res.toArray(new String[res.size()]);
    }

    /**
     * The shortcut to {@link #simpleClassName(Class) simpleClassName(o.getClass())}.
     */
    public static String simpleClassName(Object o) {
        if (o == null) {
            return "null_object";
        } else {
            return simpleClassName(o.getClass());
        }
    }

    /**
     * Generates a simplified name from a {@link Class}.  Similar to {@link Class#getSimpleName()}, but it works fine
     * with anonymous classes.
     */
    public static String simpleClassName(Class<?> clazz) {
        if (clazz == null) {
            return "null_class";
        }

        Package pkg = clazz.getPackage();
        if (pkg != null) {
            return clazz.getName().substring(pkg.getName().length() + 1);
        } else {
            return clazz.getName();
        }
    }
}