“文本”之间的区别是什么？和新的字符串（“text”）？ [英] What is the difference between "text" and new String("text")?

问题描述

以下两个陈述之间有什么区别？

What is the difference between these two following statements?

String s = "text";

String s = new String("text");

推荐答案

new String（text ）;
显式创建 String 对象的新的和引用不同的实例; String s =text; 可以重用字符串常量池中的实例（如果有的话）。

new String("text"); explicitly creates a new and referentially distinct instance of a String object; String s = "text"; may reuse an instance from the string constant pool if one is available.

你很少想要使用 new String（anotherString）构造函数。来自API：

You very rarely would ever want to use the new String(anotherString) constructor. From the API:

String（String original） ：初始化新创建的 String 对象，以便它表示与参数相同的字符序列;换句话说，新创建的字符串是参数字符串的副本。除非需要显式的原始副本，否则不必使用此构造函数，因为字符串是不可变的。

String(String original) : Initializes a newly created String object so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string. Unless an explicit copy of original is needed, use of this constructor is unnecessary since strings are immutable.

相关问题

• Java字符串：String s = new String（傻）;


• 字符串是Java中的对象，为什么我们不使用'new'来创建它们？



Related questions

• Java Strings: "String s = new String("silly");"
• Strings are objects in Java, so why don’t we use ‘new’ to create them?

检查以下代码段：

    String s1 = "foobar";
    String s2 = "foobar";

    System.out.println(s1 == s2);      // true

    s2 = new String("foobar");
    System.out.println(s1 == s2);      // false
    System.out.println(s1.equals(s2)); // true

== 关于两个参考types是参考标识比较。 等于的两个对象不一定是 == 。在引用类型上使用 == 通常是错误的;大部分时间等于需要改为使用。

== on two reference types is a reference identity comparison. Two objects that are equals are not necessarily ==. It is usually wrong to use == on reference types; most of the time equals need to be used instead.

尽管如此，如果出于某种原因需要创建两个等于但不是 == 字符串，你可以使用 new String（anotherString）构造函数。然而，需要再说一遍，这是非常特有的，很少是意图。

Nonetheless, if for whatever reason you need to create two equals but not == string, you can use the new String(anotherString) constructor. It needs to be said again, however, that this is very peculiar, and is rarely the intention.



• JLS 15.21.3参考等式运算符==和！=


• class Object - boolean Object（等于）


• JLS 15.21.3 Reference Equality Operators == and !=
• class Object - boolean Object(equals)


• Java String.equals vs. ==


• 如何比较字符串Java？


• Java String.equals versus ==
• How do I compare strings in Java?

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