JDK源码阅读之二-----String

package java.lang;import java.io.ObjectStreamClass;import java.io.ObjectStreamField;import java.io.UnsupportedEncodingException;import java.nio.charset.Charset;import java.util.ArrayList;import java.util.Arrays;import java.util.Comparator;import java.util.Formatter;import java.util.Locale;import java.util.regex.Matcher;import java.util.regex.Pattern;import java.util.regex.PatternSyntaxException; // 我擦嘞，String类import了这么多包啊/** * Strings是固定不变的; 被创建后值就不能改变了. String buffers支持可变的strings. * Because String objects are immutable they can be shared. For example: *     String str = "abc"; * 相当于: *     char data[] = {'a', 'b', 'c'}; *     String str = new String(data); * @see     java.lang.Object#toString()  * @see     java.lang.StringBuffer * @see     java.lang.StringBuilder * @see     java.nio.charset.Charset 源码里让看这个，好吧，看完StringBuffer和StringBuilder就看看NIO吧 */public final class String    implements java.io.Serializable, Comparable, CharSequence{    /** The value用来存储字符. */    private final char value[];    /** The offset is the first index of the storage that is used. */    private final int offset;    /** count是字符数组的长度，final的，长度也不能变了. */    private final int count;    /** Cache the hash code for the string */    private int hash; // Default to 0    // 构造方法很多，以后再补充吧    // 列举一些常见方法    /**     * Returns the length of this string.     */    public int length() {        return count;    }    public boolean isEmpty() {return count == 0;    }    /**     * @param      index   the index of the char value.     * @return     the char value at the specified index of this string.     *             The first char value is at index 0.     * @exception  IndexOutOfBoundsException  if the index     *             argument is negative or not less than the length of this     *             string.     */    public char charAt(int index) {        if ((index < 0) || (index >= count)) {            throw new StringIndexOutOfBoundsException(index);        }        return value[index + offset];    }    // 重写了equals方法    public boolean equals(Object anObject) {if (this == anObject) {    return true;}if (anObject instanceof String) {    String anotherString = (String)anObject;    int n = count;    if (n == anotherString.count) {char v1[] = value;char v2[] = anotherString.value;int i = offset;int j = anotherString.offset;while (n-- != 0) {    if (v1[i++] != v2[j++])return false;}return true;    }}return false;    }    // 重写hashcode方法    public int hashCode() {int h = hash;        int len = count;if (h == 0 && len > 0) {    int off = offset;    char val[] = value;            for (int i = 0; i < len; i++) {                h = 31*h + val[off++];            }            hash = h;        }        return h;    }    public String toString() {return this;    }        public native String intern(); // 这个是干嘛滴}