提问初始化问题

[oDon]

String s= {"123141231"}
与
String s= new String("123141231")
什么区别?

[晨星]

String s= {"123141231"}
可以吗？
应该是
String s= "123141231";
吧？

首先，“s”是个变量名，即“引用”，"123141231"则表示一个字符串常量。而常量本身也能代表一个运行时的对象。所以
String s = "123141231";
只是让变量s引用到一个字符串对象（即常量"123141231"所代表的那个），而“String s = new String("123141231")”，则是利用"123141231"作参数，首先构造一个新的String对象，然后让s引用到它。
所以后者比前者多产生了一个冗余对象。

[aaa2003gf]

String s= "123141231" 一个对象
String s= new String("123141231") 两个对象

[ogmios]

Because the compiler automatically creates a new String object for every literal string it encounters, you can use a literal string to initialize a String.
String s = "Test";
The above construct is equivalent to, but more efficient than, this one, which ends up creating two Strings instead of one:
String s = new String("Test");
The compiler creates the first string when it encounters the literal string "Test", and the second one when it encounters new String.
source: http://java.sun.com/docs/books/tutorial/java/data/stringsAndJavac.html

Advice: If you are C/C++ programmer be careful with shortcut assignment operator "+=" in Java when you work with Strings!

Why: The shortcut assignment operator += when used with Strings may confuse C and C++ programmers at first. Recall that a += b is equivalent to a = a + b. Let's look at two code

samples written in C++ and the Java programming language:
//C++ code
string* s1 = new string("hello");
string* s2 = s1;
(*s1) += " world";
cout<<*s1<<endl<<*s2<<endl;
return 0;
//s1 = s2 = "hello world"

//Java programming language code
String s1 = "hello";
String s2 = s1;
s1 += " world";
System.out.println(s1 + "\n" + s2);
//s1 = "hello world" and s2 = "hello"

In the C++ example, the strings s1 and s2 print the same result because they both point to the same address. In the Java programming language, Strings can't be modified, so the + operator must create a new String when "world" is appended to s1.

source: http://java.sun.com/docs/books/tutorial/java/data/stringsAndJavac.html

[cdredfox]

String s= new String("123141231")
好像也是一个对象吧，
　在JAVA中，相同的字符对象不是放在HEAD中的吗？？

[wangx1949]

第一个是一个对象
第二个是两个对象
很明显

[hongke1490]

String s= new String("123141231");
强制产生一个新对象
String s="123141231";
s会引用内存中已有的字符串
例如
String s1=new String("abc");
String s2=new String("abc");
则
s1!=s2,s1.equals(s2)=true;
若
String s1="abc";
String s2="abc";
则
s1==s2,s1.equals(s2)=true;

[chg2008]

都说很详细啊啊

[oDon]

学习了,因为自学Java很多基础都不牢固,谢谢前辈!