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    <p>So it can be evaluated during the compilation phase ( statically check ) </p> <p>See: <a href="http://docs.oracle.com/javase/specs/jls/se7/html/jls-14.html#jls-14.11" rel="noreferrer">http://docs.oracle.com/javase/specs/jls/se7/html/jls-14.html#jls-14.11</a> for a formal definition of the <code>switch</code>.</p> <p>Additionally it may help you to understand better how that <code>switch</code> is transformed into bytecode:</p> <pre><code>class Switch { void x(int n ) { switch( n ) { case 1: System.out.println("one"); break; case 9: System.out.println("nine"); break; default: System.out.println("nothing"); break; } } } </code></pre> <p>And after compiling: </p> <pre><code>C:\&gt;javap -c Switch Compiled from "Switch.java" class Switch extends java.lang.Object{ Switch(); Code: 0: aload_0 1: invokespecial #1; //Method java/lang/Object."&lt;init&gt;":()V 4: return void x(int); Code: 0: iload_1 1: lookupswitch{ //2 1: 28; 9: 39; default: 50 } 28: getstatic #2; //Field java/lang/System.out:Ljava/io/PrintStream; 31: ldc #3; //String one 33: invokevirtual #4; //Method java/io/PrintStream.println:(Ljava/lang/String;)V 36: goto 58 39: getstatic #2; //Field java/lang/System.out:Ljava/io/PrintStream; 42: ldc #5; //String nine 44: invokevirtual #4; //Method java/io/PrintStream.println:(Ljava/lang/String;)V 47: goto 58 50: getstatic #2; //Field java/lang/System.out:Ljava/io/PrintStream; 53: ldc #6; //String nothing 55: invokevirtual #4; //Method java/io/PrintStream.println:(Ljava/lang/String;)V 58: return } </code></pre> <p>See that line marked as <code>1:</code> </p> <pre><code> 1: lookupswitch{ //2 1: 28; 9: 39; default: 50 } </code></pre> <p>It evaluates the value and goes to some other line. For instance if value is <code>9</code> it will jump to instruction 39: </p> <pre><code> 39: getstatic #2; //Field java/lang/System.out:Ljava/io/PrintStream; 42: ldc #5; //String nine 44: invokevirtual #4; //Method java/io/PrintStream.println:(Ljava/lang/String;)V 47: goto 58 </code></pre> <p>Which in turn jumps to instruction 58 :</p> <pre><code> 58: return </code></pre> <p>All this wouldn't be possible if it was evaluated dynamically. That's why.</p>
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    1. POA Switch Java problem : case expressions must be constant expressions
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    1. COThanks man, that's a nice answer. So if compile with javap, i can see the bytecode generated??
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    2. CO@Dimitri. You're welcome. `javap` is another tool ( like javadoc or jar ) which is the default java dissambler. If invoked with `-c` you'll see these instructions.
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    3. COOk. But i was thinking, do you think the bytecode generated in the JVM is the same in Dalvik Machine (Android). I am working on Android as you may see it
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