如何在Java内部表示字符串？

Question

我知道C字符串abc在C内部是abc\\0 ，与Java的情况是一样的吗？

Answer 1

No, it's not the same in Java. There's no null terminator. Java strings are objects, not points to arrays of characters. It maintains the length along with the Unicode characters, so there's no need to look for a null terminator.

You don't have to ask here: look at the source for String.java in the src.zip that ships with your JDK. Here's the start of it:

public final class String
    implements java.io.Serializable, Comparable<String>, CharSequence
{
    /** The value is used for character storage. */
    private final char value[];

    /** The offset is the first index of the storage that is used. */
    private final int offset;

    /** The count is the number of characters in the String. */
    private final int count;

    /** Cache the hash code for the string */
    private int hash; // Default to 0

    /** use serialVersionUID from JDK 1.0.2 for interoperability */
    private static final long serialVersionUID = -6849794470754667710L;
}

Answer 2

Nope, C strings are an array of chars and thus there is no length associated with them. The side affect of this decision is that to determine a string's length, one must iterate through it to find the \\0 , which isn't as efficient of carrying the length around.

Java strings have a char array for their chars and carry an offset length and a string length. This means determining a string's length is rather efficient.

Source .

Answer 3

C语言中的字符串是char类型的数组，在Java中它是一个类，它表示unicode字符的集合。

Answer 4

No. Null terminators are used in C because it's easier than passing around a pointer and a size. In Java, the size is always known and so a null terminator isn't necessary. Furthermore, there are no terminating characters in Java (putting in a \\0 would be part of the literal string).

Answer 5

Java strings are not null-terminated like C strings. This is because Java stores strings' lengths. You can retrieve the length with String.length() .

Answer 6

Class String is implemented in Java. See OpenJDK's implementation for an example.

The OpenJDK 7 String class carries an array of type char[] to hold the string itself, as well as an offset (telling the first used position in the char[] ), the length of the string, and the hash code of the string.

It also has two static fields, a version ID for serialization purposes and an ObjectStreamField[] due to special casing with respect to the serialization output stream (in OpenJDK 7 at least).

Answer 7

As far as I know, in java String is stored as an object in the heap section as a sub-class of Object. There is no need to use '\\0' to specify just characters or String.