Java 语法 索引 ----- 字符串(String)

String a = "Hello";
String b = new String(" World");

//在循环里面的话要小心用
String c = a+b; // Hello World
          a += b; // Hello World


String x = "Hello " + "World";

boolean x = a.equals(b); // compares string
boolean y = (a == b); // compares address

//虽是sb但是确实很聪明
StringBuffer sb = new StringBuffer("Hello");

sb.append(" World"); // add to end of string 添加
sb.delete(0, 5); // remove 5 first characters 删除
sb.insert(0, "Hello"); // insert string at beginning 插入

String s = sb.toString();