StringBuffer操作

package dao;

public class Strbuff {
	public static void main(String[] args)
	{
		StringBuffer sb1 = new StringBuffer();
		System.out.println(sb1.capacity());
		System.out.println(sb1.length());
		System.out.println();

		StringBuffer sb2 = new StringBuffer(100);
		System.out.println(sb2.capacity());
		sb2.ensureCapacity(400);
		System.out.println(sb2.capacity());
		System.out.println();
		System.out.println(sb2.length());
	
		StringBuffer sb3 = new StringBuffer("my english is ");
		sb3.append("revy good!");
		System.out.println(sb3);

		StringBuffer sb4 = new StringBuffer("my english is ");
		sb4.append("revy good!");
		sb4.setLength(10);
		System.out.println(sb4);

		StringBuffer sb5 = new StringBuffer("my english is ");
		sb5.append("revy good!");
		sb5.setCharAt(0,'M');
		System.out.println(sb5);
		
		StringBuffer sb6 = new StringBuffer("my english is ");
		sb6.append("revy good!");
		sb6.insert(0,"congratuions !");
		System.out.println(sb6);

		StringBuffer sb7 = new StringBuffer("my english is ");
		sb7.append("revy good!");
		System.out.println(sb7.substring(10));
		System.out.println(sb7.substring(10,15));
		System.out.println(sb7.reverse());
		
		
	}
}

结果：

16
0

100
400

0
my english is revy good!
my english
My english is revy good!
congratuions !my english is revy good!
 is revy good!
 is r
!doog yver si hsilgne ym