「文字列連結の最適化」の版間の差分
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(ページの作成:「==文字列連結の最適化== [http://www.y-adagio.com/public/standards/tr_javalang2/expressions.doc.html#40226 文字列の連結が最適化されているさま…」) |
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| 1行目: | 1行目: | ||
==文字列連結の最適化== | ==文字列連結の最適化== | ||
| − | [http://www.y-adagio.com/public/standards/tr_javalang2/expressions.doc.html#40226 文字列の連結が最適化されているさま。] | + | [[http://www.y-adagio.com/public/standards/tr_javalang2/expressions.doc.html#40226 文字列の連結が最適化されているさま。]] |
/** | /** | ||
| 14行目: | 14行目: | ||
} | } | ||
| − | + | >javac OptStrConcatTest.java | |
| − | + | >javap -c SbTest > SbTest.jc | |
Compiled from "OptStrConcatTest.java" | Compiled from "OptStrConcatTest.java" | ||
| 22行目: | 22行目: | ||
Code: | Code: | ||
0: aload_0 | 0: aload_0 | ||
| − | 1: invokespecial #1; //Method java/lang/Object." | + | 1: invokespecial #1; //Method java/lang/Object."<init>":()V |
4: return | 4: return | ||
| 29行目: | 29行目: | ||
0: new #2; //class StringBuffer | 0: new #2; //class StringBuffer | ||
3: dup | 3: dup | ||
| − | 4: invokespecial #3; //Method java/lang/StringBuffer." | + | 4: invokespecial #3; //Method java/lang/StringBuffer."<init>":()V |
7: aload_0 | 7: aload_0 | ||
8: iconst_0 | 8: iconst_0 | ||
2020年2月15日 (土) 08:00時点における版
文字列連結の最適化
/**
* @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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