該類被final修飾,所以不能被繼承,並且繼承了AbstractStringBuilder,實現了java.io.Serializable, CharSequence兩個接口。
構造方法:public StringBuffer(){
super(16) ;
}
public StringBuffer(int capacity); 初始化stringbuffer容量
public StringBuffer(String str); //用字符串初始化StringBuffer.代碼實現是先構建個容量爲str.length+16的空stringbuffer,然後將str添加進stringbuffer.所以構造的stringbuffer大小比str大16
public StringBuffer(CharSequence seq); 類似用string初始化
public synchronized int length(); 獲取字符串長度
public synchronized int capacity(); 獲取stringBuffer容量
public synchronized void ensureCapacity(int minimumCapacity) //確保容量最小爲minimumCapacity
public sysnchronized void trimToSize(); //調用父類trimToSize
public synchronized void setLength(int newLength) ;//重新設置長度爲newLength
public synchronized char charAt(int index) ;//返回value[index] 返回指定位置的字符
public synchronized int codePointAt(int index) ; //返回指定位置字符的編碼
public synchronized int codePointBefore(int index) ;//指定位置之前的一個字符的編碼
public synchronized int offsetByCodePoints(int index, int codePointOffset); //返回從index開始codePointOffset處的字符索引
public synchronized void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin); //將該stringbuffer從srcBegin到srcEnd範圍內的子串複製到目的字符數組dst中,並且複製過去的字符串在dst中的起始位置是dstBegin。
public synchronized void setCharAt(int index, char ch);//將指定位置的字符設置成ch
public synchronized StringBuffer append(Object obj);//將obj以字符串形式添加到stringbuffer
public synchronized StringBuffer append(String str);// 添加字符串
public synchronized StringBuffer append(StringBuffer sb); //添加StringBufferf
public StringBuffer append(CharSequence s) ;//添加字符序列
public synchronized StringBuffer append(CharSequence s, int start, int end);//將字符序列s從start到end之間子串添加到stringbuffer
public synchronized StringBuffer append(char[] str) ;//添加一個字符數組
public synchronized StringBuffer append(char[] str, int offset, int len);// str從offset開始,長度爲len的字符添加到stringbuffer
public synchronized StringBuffer append(boolean b);//添加布爾值
public synchronized StringBuffer append(char c);//添加字符
public synchronized StringBuffer append(int i);//添加整數
public synchronized StringBuffer appendCodePoint(int codePoint);//根據ASCII嗎添加字符
public synchronized StringBuffer append(long lng); 添加整數
public synchronized StringBuffer append(float f);添加浮點數
public synchronized StringBuffer append(double d);添加雙精度浮點數
public synchronized StringBuffer delete(int start, int end);刪除範圍內的子串
public synchronized StringBuffer deleteCharAt(int index);刪除指定位置的字符
public synchronized StringBuffer replace(int start, int end, String str);start–end之間的子串用str替換
public synchronized String substring(int start);獲取從start開始到結束的子串
public synchronized CharSequence subSequence(int start, int end);獲取範圍內 的字符序列
public synchronized String substring(int start, int end);獲取範圍內的子串
public synchronized StringBuffer insert(int index, char[] str, int offset, int len); 從index開始插入str的子串,str的子串爲從offset開始,長度爲len的子串
public synchronized StringBuffer insert(int offset, Object obj) ;在指定索引處插入Obj
public synchronized StringBuffer insert(int offset, String str) ;在指定索引處插入字符串
public synchronized StringBuffer insert(int offset, char[] str) ; 在一定索引處插入字符數組
public StringBuffer insert(int dstOffset, CharSequence s) ; 插入s
public synchronized StringBuffer insert(int dstOffset, CharSequence s, int start, int end);在指定位置開始,插入s的子串:從start開始,end之前的子串
public StringBuffer insert(int offset, boolean b);指定位置插入布爾值
public synchronized StringBuffer insert(int offset, char c) ;指定位置插入字符
public StringBuffer insert(int offset, int i) ;指定位置插入整數
public StringBuffer insert(int offset, long l);指定位置插入長整型
public StringBuffer insert(int offset, float f);指定位置插入浮點型
public StringBuffer insert(int offset, double d);指定位置插入雙精度浮點型
public int indexOf(String str);返回字符串str的索引
public synchronized int indexOf(String str, int fromIndex);返回字符串str從fromindex開始出現在stringbuffer中的索引
public int lastIndexOf(String str) ;返回子串str最後的索引
public synchronized int lastIndexOf(String str, int fromIndex);從fromindex開始,返回str最後的索引
public synchronized StringBuffer reverse();將stringbuffer反轉
public synchronized String toString();