String和StringBuilder的区别:
String:内容是不可变的
StringBuilder:内容是可变的
public StringBuilder( );创建一个空白可变字符串对象,不含任何内容
public StringBuilder( String str);根据字符串的内容,来创建可变字符串对象
public class Application { public static void main(String[] args) { StringBuilder sc = new StringBuilder(); System.out.println(sc); System.out.println(sc.length()); StringBuilder sc2 = new StringBuilder("mqs"); System.out.println(sc2); System.out.println(sc2.length()); } }
public class Application { public static void main(String[] args) { StringBuilder sc = new StringBuilder(); sc.append("mqs"); System.out.println(sc); //链式编程 sc.append("mqs1").append("mqs2"); System.out.println(sc);
sc.reverse(); System.out.println(sc);
} }