把List轉化爲以","隔開的字符串的方法

1. [代碼][Java]代碼    

import java.util.ArrayList; import java.util.List; /**  * 集合操作  */ public class Test {       public static void main(String[] args) {         List<String> list= new ArrayList<String>();         list.add("aaa");         list.add("bbb");         list.add("ccc");         System.out.println(listToString(list));//aaa,bbb,ccc     }           public static String listToString(List<String> stringList){         if(stringList==null) {             returnnull;         }         StringBuilder result = new StringBuilder();         booleanflag=false;         for(String string : stringList) {             if(flag) {                 result.append(",");             }else{                 flag=true;             }             result.append(string);         }         return result.toString();     } }

2. [代碼][Java]代碼   

import java.util.ArrayList; import java.util.List; /**  *集合對象操作  */ public class Test {       publicstaticvoidmain(String[] args) {           List<Person> list =newArrayList<Person>();         list.add(newPerson("張三",15));         list.add(newPerson("李四",12));         list.add(newPerson("王五",10));         // 打印年齡不小於12歲的人員         System.out.println(listToString(list,12,"&"));// 張三&李四     }       /**      * 獲取年齡>=age的人員信息      */     publicstaticString listToString(List<Person> list,intage, String sep) {         if(list ==null) {             returnnull;         }         StringBuilder result =newStringBuilder();         booleanflag =false;         for(Person person : list) {             if(person.getAge() < age) {                 continue;             }             if(flag) {                 result.append(sep==null?"":sep);             }else{                 flag =true;             }             result.append(person.toString());         }         returnresult.toString();     } }   class Person {     privateString name;     privateintage;       publicPerson() {     }       publicPerson(String name,intage) {         this.name = name;         this.age = age;     }       publicString getName() {         if(name ==null) {             name ="";         }         returnname;     }       publicvoidsetName(String name) {         this.name = name;     }       publicintgetAge() {         returnage;     }       publicvoidsetAge(intage) {         this.age = age;     }       @Override     publicString toString() {         returngetName();     } }