Java String 翻译
The String class represents(表示，描述) character strings. All string literals in Java programs, such(例如) as "abc", are implemented as instances of this class.
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Strings are constant(常量); their values cannot be changed after they are created. String buffers(缓冲) support mutable(可变) strings. Because String objects are immutable(不可变) they can be shared. For example:
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String str = "abc";
is equivalent(等值的) to:
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char data[] = {'a', 'b', 'c'}; String str = new String(data); Here are some more examples of how strings can be used:
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System.out.println("abc"); String cde = "cde"; System.out.println("abc" + cde); String c = "abc".substring(2,3); String d = cde.substring(1, 2); The class String includes methods for examining(检查) individual(个体) characters of the sequence, for comparing(比较) strings, for searching strings, for extracting(提起) substrings, and for creating a copy of a string with all characters translated to uppercase or to lowercase. Case mapping is based on the Unicode Standard(标准) version specified by the Character class.
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The Java language provides(提供) special(特别) support for the string concatenation(连接) operator ( + ), and for conversion of other objects to strings. String concatenation is implemented through the StringBuilder(or StringBuffer) class and its append method. String conversions are implemented through the method toString, defined by Object and inherited(继承) by all classes in Java. For additional(额外的) information on string concatenation and conversion, see Gosling, Joy, and Steele, The Java Language Specification.
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Unless(除非) otherwise(另外) noted, passing a null argument to a constructor or method in this class will cause(引起) a NullPointerException to be thrown.
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A String represents a string in the UTF-16 format in which supplementary(增补) characters are represented by surrogate pairs (see the section Unicode Character Representations in the Character class for more information). Index values refer(指) to char code units(单元，单位), so a supplementary character uses two positions in a String.
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The String class provides methods for dealing with Unicode code points (i.e., characters), in addition(添加) to those for dealing(行为) with Unicode code units (i.e., char values).