拼接以 “逗号” 隔开的String字符串，String字符串按照 “逗号” 分割

一、拼接以 “逗号” 隔开的String字符串

如果需要对字符串进行频繁拼接的话，使用StringBuffer或者StringBuilder
StringBuffer:【字符串缓冲器】是线程安全的，效率低
StringBuilder：【字符串操作类】是线程不安全的，效率高

public static void main(String[] args){
    	
    	String aa = "11";
    	String bb = "22";
    	String cc = "33";
    	
    	String result = "";
    	StringBuilder builder = new StringBuilder();
    	StringBuffer buffer = new StringBuffer();
    	
    	result = result + aa + "," + bb + "," + cc;
    	builder.append(aa).append(",").append(bb).append(",").append(cc);
    	buffer.append(aa).append(",").append(bb).append(",").append(cc);
    	
    	System.out.println("result = " + result);
    	System.out.println("builder = " + builder);
    	System.out.println("buffer = " + buffer);
    	
    }

结果：
result = 11,22,33
builder = 11,22,33
buffer = 11,22,33

二、String字符串按照 “逗号” 分割

public static void main(String[] args){
    	String aa = "1,aa,rfg,wer";
    	// 根据,(逗号)进行分割
    	String[] results = aa.split(",");
    	for(int i = 0; i < results.length; i++) {
    		System.out.println("i = " + results[i]);
    	}
    }

结果：
i = 1
i = aa
i = rfg
i = wer