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64 lines
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64 lines
3.9 KiB
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<html><head><base href="placeholder"> <style type="text/css"> #error { background-color: #eeeeee; margin-bottom: 10px; } p { margin: 5px 0; } </style></head><body><small><b>java.lang</b></small><PRE>public final class <b>String</b>
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extends <a href="psi_element://java.lang.Object"><code>java.lang.Object</code></a>
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implements <a href="psi_element://java.io.Serializable"><code>java.io.Serializable</code></a>, <a href="psi_element://java.lang.Comparable"><code>java.lang.Comparable</code></a><<a href="psi_element://java.lang.String"><code>String</code></a>>, <a href="psi_element://java.lang.CharSequence"><code>java.lang.CharSequence</code></a></PRE>
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The <code>String</code> class represents character strings. All
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string literals in Java programs, such as <code>"abc"</code>, are
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implemented as instances of this class.
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<p>
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Strings are constant; their values cannot be changed after they
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are created. String buffers support mutable strings.
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Because String objects are immutable they can be shared. For example:
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<p><blockquote><pre>
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String str = "abc";
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</pre></blockquote><p>
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is equivalent to:
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<p><blockquote><pre>
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char data[] = {'a', 'b', 'c'};
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String str = new String(data);
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</pre></blockquote><p>
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Here are some more examples of how strings can be used:
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<p><blockquote><pre>
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System.out.println("abc");
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String cde = "cde";
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System.out.println("abc" + cde);
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String c = "abc".substring(2,3);
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String d = cde.substring(1, 2);
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</pre></blockquote>
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<p>
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The class <code>String</code> includes methods for examining
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individual characters of the sequence, for comparing strings, for
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searching strings, for extracting substrings, and for creating a
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copy of a string with all characters translated to uppercase or to
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lowercase. Case mapping is based on the Unicode Standard version
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specified by the <a href="psi_element://java.lang.Character"><code>Character</code></a> class.
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<p>
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The Java language provides special support for the string
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concatenation operator ( + ), and for conversion of
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other objects to strings. String concatenation is implemented
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through the <code>StringBuilder</code>(or <code>StringBuffer</code>)
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class and its <code>append</code> method.
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String conversions are implemented through the method
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<code>toString</code>, defined by <code>Object</code> and
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inherited by all classes in Java. For additional information on
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string concatenation and conversion, see Gosling, Joy, and Steele,
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<i>The Java Language Specification</i>.
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<p> Unless otherwise noted, passing a <tt>null</tt> argument to a constructor
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or method in this class will cause a <a href="psi_element://java.lang.NullPointerException"><code>NullPointerException</code></a> to be
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thrown.
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<p>A <code>String</code> represents a string in the UTF-16 format
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in which <em>supplementary characters</em> are represented by <em>surrogate
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pairs</em> (see the section <a href="psi_element://java.lang.Character###unicode">Unicode
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Character Representations</a> in the <code>Character</code> class for
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more information).
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Index values refer to <code>char</code> code units, so a supplementary
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character uses two positions in a <code>String</code>.
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<p>The <code>String</code> class provides methods for dealing with
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Unicode code points (i.e., characters), in addition to those for
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dealing with Unicode code units (i.e., <code>char</code> values).
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<DD><DL><DT><b>Since:</b><DD>JDK1.0</DD></DL></DD><DD><DL><DT><b>See Also:</b><DD><a href="psi_element://java.lang.Object#toString()"><code>Object.toString()</code></a>,
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<a href="psi_element://java.lang.StringBuffer"><code>StringBuffer</code></a>,
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<a href="psi_element://java.lang.StringBuilder"><code>StringBuilder</code></a>,
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<font color=red>java.nio.charset.Charset</font></DD></DL></DD></body></html> |