StringBulider（常用）与StringBuffer

/**
 * 可变字符序列
 * StringBuilder(线程不安全,效率高,一般用这个),
 * StringBuffer(线程安全)
 * 
 * @author Administrator
 *
 */
public class TestStringBuilder {
	public static void main(String[] args) {
		//初始化为16位，但不放东西.lengh()为0.
		StringBuilder sb = new StringBuilder();
		System.out.println("sb长度:"+sb.length());
		System.out.println();
		//自定义长度32
		StringBuilder sb1 = new StringBuilder(32);
		//value[]={'a','b','c','d',/u0000,/u0000,.....}
		StringBuilder sb2 = new StringBuilder("abcd");
		System.out.println("sb2长度:"+sb2.length());
		//value[]={'a','b','c','d','e','f','g','h',/u0000,/u0000,.....}
		sb2.append("efgh");
		//return this;构造方法链，返回值仍为sb2对象，所以可以一直调用此方法;
		sb2.append('t').append("jjj").append(52);
		System.out.println("sb1长度:"+sb1.length());
		System.out.println("sb2长度:"+sb2.length());
	}
}