字符串连接误用

错误的写法：

• String s = "";  
• for (Person p : persons) {  
•     s += ", " + p.getName();  
• }  
• s = s.substring(2); //remove first comma
  

正确的写法：

• StringBuilder sb = new StringBuilder(persons.size() * 16); // well estimated buffer  
• for (Person p : persons) {  
•     if (sb.length() > 0) sb.append(", ");  
•     sb.append(p.getName);  
• }
  

字符串连接误用

错误的写法：

• String s = "";  
• for (Person p : persons) {  
•     s += ", " + p.getName();  
• }  
• s = s.substring(2); //remove first comma
  

正确的写法：

• StringBuilder sb = new StringBuilder(persons.size() * 16); // well estimated buffer  
• for (Person p : persons) {  
•     if (sb.length() > 0) sb.append(", ");  
•     sb.append(p.getName);  
• }