String类、StringBuffer（线程安全）、StringBuilder（效率高，非线程安全）

1、String.format()

logger.info(String.format("打印日志%s,%s,%b", stringA,stringB,booleanC));

-- Java 字符串格式化详解
https://www.cnblogs.com/travellife/p/Java-zi-fu-chuan-ge-shi-hua-xiang-jie.html

2、区分String StringBuilder StringBuffer
http://blog.csdn.net/helongzhong/article/details/54090754
https://blog.csdn.net/djjt10/article/details/52860010
https://www.cnblogs.com/xingzc/p/6277581.html
http://www.cnblogs.com/sevenlin/p/sevenlin_StringBuffer_StringBuilder20150806.html

3、toString（）方法
方法一、

@Override
public String toString() {
	return "DemoClass[name=" + name+ ", age=" + age+ "]";
}

方法二、

import org.apache.commons.lang.builder.ReflectionToStringBuilder;
@Override
public String toString() {
	return ReflectionToStringBuilder.toString(this);
}

方法三、借助JSON工具类

import com.alibaba.fastjson.JSONObject;
	@Override
    public String toString() {
        return JSONObject.toJSONString(this);
    }