JavaString

 

public class test {

    public static void main(String[] args) {

        // 通过字符获取对应的ascii码值
        char a = '0';
        System.out.println(Integer.valueOf(a));

        // 通过ascii码值获取对应表示的字符
        int b = 48;
        System.out.println((char)b);
    }
}

 

 

 

 字符串源码：

public final class String implements java.io.Serializable, Comparable<java.lang.String>, CharSequence {
    /** The value is used for character storage. */
    private final char value[];
    /** Cache the hash code for the string */
    private int hash; // Default to 0
    /** use serialVersionUID from JDK 1.0.2 for interoperability */
    private static final long serialVersionUID = -6849794470754667710L;

    /**
     * 字符串的构造方法
     */
    public String()
    public String(java.lang.String original)
    public String(char value[])
    public String(char value[], int offset, int count)
    public String(int[] codePoints, int offset, int count)
    @Deprecated
    public String(byte ascii[], int hibyte, int offset, int count)
    @Deprecated
    public String(byte ascii[], int hibyte)
    public String(byte bytes[], int offset, int length, java.lang.String charsetName)
    public String(byte bytes[], int offset, int length, Charset charset)
    public String(byte bytes[], java.lang.String charsetName)
    public String(byte bytes[], Charset charset)
    public String(byte bytes[], int offset, int length)
    public String(byte bytes[])
    public String(StringBuffer buffer)
    public String(StringBuilder builder)

    // 获取字符串的长度
    public int length()

    // 判断字符串是否为空,长度为0
    public boolean isEmpty()
    
    // 字符串去前后空白, 例如: "zhangsan".trim()
    public java.lang.String trim()
        
    public java.lang.String toString()
    public int hashCode()

    // 将字符串转成字符数组, 例如:  "zhangsan".toCharArray()
    public char[] toCharArray()

    // 获取索引位置对应的字符, 例如: "zhangsan".charAt(0) -> z
    public char charAt(int index)
    // 获取索引位置对应的字符unicode值, "zhangsan".codePointAt(0) -> 122  (122对应unicode的小写的z)
    public int codePointAt(int index)
    public int codePointBefore(int index)
    public int codePointCount(int beginIndex, int endIndex)
    public int offsetByCodePoints(int index, int codePointOffset)

    // 将字符串按照指定的字符集编码转成字节数组
    public byte[] getBytes(java.lang.String charsetName)
    public byte[] getBytes(Charset charset)
    public byte[] getBytes()


    // 字符串与另外一个字符串比较
    public boolean equals(Object anObject)
    public boolean contentEquals(StringBuffer sb)
    private boolean nonSyncContentEquals(AbstractStringBuilder sb)
    public boolean contentEquals(CharSequence cs)
    public boolean equalsIgnoreCase(java.lang.String anotherString)
    public int compareTo(java.lang.String anotherString)
    public int compareToIgnoreCase(java.lang.String str)

    public boolean regionMatches(int toffset, java.lang.String other, int ooffset,int len)
    public boolean regionMatches(boolean ignoreCase, int toffset,java.lang.String other, int ooffset, int len)

        
    // 判断是否已某个子串开头
    public boolean startsWith(java.lang.String prefix, int toffset)
    public boolean startsWith(java.lang.String prefix)
    public boolean endsWith(java.lang.String suffix)


    // 查找第一次出现的指定的unicode值的索引位置
    public int indexOf(int ch)
    public int indexOf(int ch, int fromIndex)

        
    // 查找最后一次出现的指定的unicode值的索引位置
    public int lastIndexOf(int ch)
    // 从fromIndex位置开始往前找最后一次出现的指定的unicode值的索引位置
    public int lastIndexOf(int ch, int fromIndex)
    private int lastIndexOfSupplementary(int ch, int fromIndex)

        
    // 查找子串在字符串出现的起始索引
    public int indexOf(java.lang.String str)
    public int indexOf(java.lang.String str, int fromIndex)
    public int lastIndexOf(java.lang.String str)
    public int lastIndexOf(java.lang.String str, int fromIndex)

        
    // 根据索引截取字符串
    public java.lang.String substring(int beginIndex)
    public java.lang.String substring(int beginIndex, int endIndex)

        
    // 根据开始结束索引, 获取一个字符序列
    public CharSequence subSequence(int beginIndex, int endIndex)

        
    // 将字符串拼接上另外一个字符串
    public java.lang.String concat(java.lang.String str)

        
    // 根据正则匹配字符串
    public boolean matches(java.lang.String regex)
    // 判断字符串是否包含某个子串
    public boolean contains(CharSequence s)


    // 将字符串中某个子串替换为新的子串
    public java.lang.String replace(char oldChar, char newChar)
    public java.lang.String replaceFirst(java.lang.String regex, java.lang.String replacement)
    public java.lang.String replaceAll(java.lang.String regex, java.lang.String replacement)
    public java.lang.String replace(CharSequence target, CharSequence replacement)

        
    // 根据正则表达式, 将字符串进行拆分, 例如:   "张三, 李四, 王五".split(",") -> [张三, 李四, 王五]
    public java.lang.String[] split(java.lang.String regex, int limit)
    public java.lang.String[] split(java.lang.String regex)

        
    // 将字符序列以指定的分隔符拼接, 例如: String.join("-", "a", "b", "c") -> a-b-c
    public static java.lang.String join(CharSequence delimiter, CharSequence... elements)
    // 将一个元素为字符序列的迭代器以指定的分隔符拼接, 例如: String.join("-", ["a", "b", "c"]) -> a-b-c
    public static java.lang.String join(CharSequence delimiter,Iterable<? extends CharSequence> elements)

        
    // 转小写
    public java.lang.String toLowerCase(Locale locale)
    public java.lang.String toLowerCase()
    // 转大写
    public java.lang.String toUpperCase(Locale locale)
    public java.lang.String toUpperCase()


    // 字符串格式化, String.format()
    public static java.lang.String format(java.lang.String format, Object... args)
    public static java.lang.String format(Locale l, java.lang.String format, Object... args)


    public static java.lang.String valueOf(Object obj)
    // 将字符数组转成字符串
    public static java.lang.String valueOf(char data[])
    // 将字符数组 从offset开始, 一共取count个字符, 转成字符串
    public static java.lang.String valueOf(char data[], int offset, int count)
    // 拷贝指定的字符数组, 转成字符串
    public static java.lang.String copyValueOf(char data[])
    // 拷贝指定的字符数组, 从offset开始, 一共取count个字符, 转成字符串
    public static java.lang.String copyValueOf(char data[], int offset, int count)


    // 基本数据类型转字符串类型   String.valueOf(基本数据类型的值)
    public static java.lang.String valueOf(boolean b)
    public static java.lang.String valueOf(char c)
    public static java.lang.String valueOf(int i)
    public static java.lang.String valueOf(long l)
    public static java.lang.String valueOf(float f)
    public static java.lang.String valueOf(double d)
}