new String比字符串池浪费空间,为什么要用它?_new string造成浪费-优快云博客

对于下面程序中：ss0 = new String( "hello" );是用new()来新建对象的，存于堆中。每调用一次就会创建一个新的对象。当然从节省空间的角度来讲，肯定不如str="hello"，有童鞋一定问，那要它有什么用？当时设计编译器时，为什么要设计它？那我请问你，如果在你编程序时，你还不知道字符串内容怎么办？这时就用到new String(String original)，所以，什么都有什么的用处。

(注意不能看调试窗口里value id，eclipse的问题)

public class Test
{
    public static void main(String args[]) {
        String str, str1, ss0, ss1, ss2, ss3, ss4;
        str = "hello";
        str1 = "hello";
        ss0 = new String("hello");
        ss1 = new String("hello");
        ss2 = new String("bye");
        ss3 = new String("chi le ma");
        ss4 = new String("chi le ma");
/* ==在测内存地址是否相同，如果相同，就证明是同一个对象。== means address space is the same.str and str1 point to the same
String constant.only one place
*/
        System.out.println(str1 == str);
        System.out.println(ss1 == ss0);
/* equals 是看内容是否相等，equals means as long as value is the same, it is the same.but == mean
memory address should be the same. */
        System.out.println(ss1.equals("hello"));
        System.out.println(str1 == "hello");
        System.out.println(ss1 == "hello");
    }
}

String class contains a static method, valueOf(). With it, you can create a String object from a value of any of the basic types
String pi = String.valueOf(3.14159);
String对象的运算符：“+”。用来连接两个字符串。