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49 lines
5.8 KiB
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<html><head><base href="placeholder"></head><body><div class="bottom"><icon src="AllIcons.Nodes.Package"> <a href="psi_element://java.lang"><code><span style="color:#000000;">java.lang</span></code></a></div><div class='definition'><pre><span style="color:#000080;font-weight:bold;">public final</span> <span style="color:#000080;font-weight:bold;">class</span> <span style="color:#000000;">String</span>
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<span style="color:#000080;font-weight:bold;">implements</span> <a href="psi_element://java.io.Serializable"><code><span style="color:#000000;">java.io.Serializable</span></code></a><span style="">,</span> <a href="psi_element://java.lang.Comparable"><code><span style="color:#000000;">Comparable</span></code></a><span style=""><</span><a href="psi_element://java.lang.String"><code><span style="color:#000000;">String</span></code></a><span style="">></span><span style="">,</span> <a href="psi_element://java.lang.CharSequence"><code><span style="color:#000000;">CharSequence</span></code></a></pre></div><div class='content'>
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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><pre><code><span style="">String str = </span><span style="color:#008000;font-weight:bold;">"abc"</span><span style="">;</span></code></pre><p>
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is equivalent to:
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<p><pre><code><span style="color:#000080;font-weight:bold;">char </span><span style="">data[] = {</span><span style="color:#008000;font-weight:bold;">'a'</span><span style="">, </span><span style="color:#008000;font-weight:bold;">'b'</span><span style="">, </span><span style="color:#008000;font-weight:bold;">'c'</span><span style="">};<br></span><span style="">String str = </span><span style="color:#000080;font-weight:bold;">new </span><span style="">String(data);</span></code></pre><p>
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Here are some more examples of how strings can be used:
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<p><pre><code><span style="">System.out.println(</span><span style="color:#008000;font-weight:bold;">"abc"</span><span style="">);<br></span><span style="">String cde = </span><span style="color:#008000;font-weight:bold;">"cde"</span><span style="">;<br></span><span style="">System.out.println(</span><span style="color:#008000;font-weight:bold;">"abc" </span><span style="">+ cde);<br></span><span style="">String c = </span><span style="color:#008000;font-weight:bold;">"abc"</span><span style="">.substring(</span><span style="color:#0000ff;">2</span><span style="">,</span><span style="color:#0000ff;">3</span><span style="">);<br></span><span style="">String d = cde.substring(</span><span style="color:#0000ff;">1</span><span style="">, </span><span style="color:#0000ff;">2</span><span style="">);</span></code></pre>
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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><span style="color:#0000ff;">Character</span></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><span style="color:#0000ff;">NullPointerException</span></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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</div><table class='sections'><p><tr><td valign='top' class='section'><p>Since:</td><td valign='top'><p> JDK1.0</td><tr><td valign='top' class='section'><p>See Also:</td><td valign='top'><p><a href="psi_element://java.lang.Object#toString()"><code><span style="color:#0000ff;">Object</span><span style="">.</span><span style="color:#0000ff;">toString</span><span style="">()</span></code></a>,<br><a href="psi_element://java.lang.StringBuffer"><code><span style="color:#0000ff;">StringBuffer</span></code></a>,<br><a href="psi_element://java.lang.StringBuilder"><code><span style="color:#0000ff;">StringBuilder</span></code></a>,<br><span style="color:#ff0000">java.nio.charset.Charset</span></td><tr><td valign='top' class='section'><p>Author:</td><td valign='top'><p>Lee Boynton, Arthur van Hoff, Martin Buchholz, Ulf Zibis</td></table> |