JavaSE8基础 StringBuffer的三种构造方法

os ：windows7 x64
    jdk：jdk-8u131-windows-x64
    ide：Eclipse Oxygen Release (4.7.0)
    
    
code：

package jizuiku0;

public class Demo00 {
	public static void main(String[] args) {
		//无参构造
		StringBuffer sb = new StringBuffer();//看API手册+源码可得,初始容量为16
		System.out.println(sb.toString());
		System.out.println(sb.length());//实际长度:0
		System.out.println(sb.capacity());//capacity容量:16

		System.out.println("-------------------------");

		//指定capacity构造
		StringBuffer sb1 = new StringBuffer(50);//看API手册+源码可得,初始容量为50
		System.out.println(sb1.toString());
		System.out.println(sb1.length());//实际长度:0
		System.out.println(sb1.capacity());//capacity容量:50

		System.out.println("-------------------------");

		//指定字符串构造
		StringBuffer sb2 = new StringBuffer("jizuiku");//看API手册+源码可得,初始容量为str.length()+16
		System.out.println(sb2.toString());
		System.out.println(sb2.length());//实际长度:7
		System.out.println(sb2.capacity());//capacity容量:7+16
	}
}

result：