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);