15-StringBuffer-10-常用对象API(StringBuffer类-插入&删除&查找&修改)

package cn.itcast.stringbuffer.demo;

public class StringBufferDemo2 {

public static void main(String[] args) {

/*
* StringBuffer的删除操作：
* 		StringBuffer delete(start,end)//包含头，不包含尾，其实是删除角标从start到end-1的元素
* 		StringBuffer delete(int index)//删除指定位置的元素
*
* StringBuffer的替换操作
* 		StringBuffer replace(int start,int end,String str)//将角标从start到end-1位置所有字符串一起替换为str
* 		void setCharAt(int start,char ch)//将start位置的原内容替换为字符ch
*
* 增删改查C(create)U(update)R(read)D(delete)
*/
//stringBufferDemo_2();
//		stringBufferDemo_3();
stringBufferDemo_4();
}

private static void stringBufferDemo_4() {
StringBuffer sb = new StringBuffer("abcd");
sb.setLength(10);
System.out.println("sb:"+sb);
}

private static void stringBufferDemo_3() {
StringBuffer sb = new StringBuffer("abcd");
//sb.replace(1, 3, "nba");
sb.setCharAt(2, 'q');
System.out.println(sb);
}

private static void stringBufferDemo_2() {
StringBuffer sb = new StringBuffer("abcd");

//	sb.delete(1, 3);//sop（sb）输出ad

//清空缓冲区
sb.delete(0, sb.length());//有一个盆，揉了半天面，把面倒掉，但是盆还在，故这方法删除之后缓冲区sb还在
//	StringBuffer sb = new StringBuffer();//有一个盆，揉了半天面，把面和盆一起扔了，买个新盆，这方法不靠谱
System.out.println(sb);
}

}