文字列連結の最適化

文字列連結の最適化

文字列の連結が最適化されているさま。

/**
 * @see JSL 15.18.1.2 Optimization of String Concatenation 
 */
public class OptStrConcatTest {
   
  public static void main(String[] args) {

    String s2 = args[0] + args[1] + args[2];
  }
}

>javac OptStrConcatTest.java
>javap -c SbTest > SbTest.jc

Compiled from "OptStrConcatTest.java"
public class OptStrConcatTest extends java.lang.Object{
public OptStrConcatTest();
  Code:
   0:	aload_0
   1:	invokespecial	#1; //Method java/lang/Object."<init>":()V
   4:	return

public static void main(java.lang.String[]);
  Code:
   0:	new	#2; //class StringBuffer
   3:	dup
   4:	invokespecial	#3; //Method java/lang/StringBuffer."<init>":()V
   7:	aload_0
   8:	iconst_0
   9:	aaload
   10:	invokevirtual	#4; //Method java/lang/StringBuffer.append:(Ljava/lang/String;)Ljava/lang/StringBuffer;
   13:	aload_0
   14:	iconst_1
   15:	aaload
   16:	invokevirtual	#4; //Method java/lang/StringBuffer.append:(Ljava/lang/String;)Ljava/lang/StringBuffer;
   19:	aload_0
   20:	iconst_2
   21:	aaload
   22:	invokevirtual	#4; //Method java/lang/StringBuffer.append:(Ljava/lang/String;)Ljava/lang/StringBuffer;
   25:	invokevirtual	#5; //Method java/lang/StringBuffer.toString:()Ljava/lang/String;
   28:	astore_1
   29:	return
}

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