字符串拼接详解，直白明了。

public class Main {
	
	    public static void main(String args[]) {   
	    	//字符串拼接 ：下边的sql语句的字符串原理拼接参考下边的分解步骤就明白了。
	    	//sql = "insert into tb_articleType values ('" + single.getTypeName()+ "','" + single.getTypeInfo() + "')";
	        String string1 = "天海网："; 
	        String string2 = "www.035123.com/sm"; 
	       // System.out.println("insert into tb_articleType values ('" + string1 + "','" + string2  + "')");
	        //System.out.println("insert into tb_articleType values ('" + string1 + "','" + string2  + "')");
	        System.out.println(" ('" + string1 + "','" + string2  + "')");
	        System.out.println(" ('");
	        System.out.println("')");
	        System.out.println(" ('"+"')");
	        System.out.println(" ('"+string1+"')");
	        System.out.println(" ('"+string1+","+"')");
	        System.out.println(" ('"+string1+"','"+"')");
	        System.out.println(" ('"+string1+"','"+string2+"')");
	    }
}

 ('天海网：','www.035123.com/sm')
 ('
')
 ('')
 ('天海网：')
 ('天海网：,')
 ('天海网：','')
 ('天海网：','www.035123.com/sm')