集合或数组转成String字符串

String s="";
for (int i = 0; i < numList.size(); i++) {
    if (s=="") {
	s=numList.get(i);
    }else {
	s=s+","+numList.get(i);
    }
}

List<String> numList=new ArrayList<String>();
for(int i=1; i<10; i++){
   numList.add(String.valueOf(i));     
}

String [] arr = {"abc", "123", "@#&"};
	StringBuffer sb = new StringBuffer();
	for(int i = 0; i < arr.length; i++){
	sb. append(arr[i]);
	}

	String ns = sb.toString();
	
	System.out.println(ns);
	
	}