Kev Jackson wrote:
> It's less to do with speed performance and more to do with memory
> performance. "a" + "b" + "c" creates "a" + "bc" <- intermediate String,
> and then "abc"
Many years ago - yes, but not now.
java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode)
public class AAA {
public String concat(String a, String b, String c) {
return a + b + c;
}
}
javac AAA.java
javap -c AAA
public java.lang.String concat(java.lang.String, java.lang.String,
java.lang.String);
Code:
0: new #2; //class java/lang/StringBuilder
3: dup
4: invokespecial #3; //Method java/lang/StringBuilder."<init>":()V
7: aload_1
8: invokevirtual #4; //Method
java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
11: aload_2
12: invokevirtual #4; //Method
java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
15: aload_3
16: invokevirtual #4; //Method
java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
19: invokevirtual #5; //Method
java/lang/StringBuilder.toString:()Ljava/lang/String;
22: areturn
javac -source 1.4 -target 1.4 AAA.java
javap -c AAA
public java.lang.String concat(java.lang.String, java.lang.String,
java.lang.String);
Code:
0: new #2; //class java/lang/StringBuffer
3: dup
4: invokespecial #3; //Method java/lang/StringBuffer."<init>":()V
7: aload_1
8: invokevirtual #4; //Method
java/lang/StringBuffer.append:(Ljava/lang/String;)Ljava/lang/StringBuffer;
11: aload_2
12: invokevirtual #4; //Method
java/lang/StringBuffer.append:(Ljava/lang/String;)Ljava/lang/StringBuffer;
15: aload_3
16: invokevirtual #4; //Method
java/lang/StringBuffer.append:(Ljava/lang/String;)Ljava/lang/StringBuffer;
19: invokevirtual #5; //Method
java/lang/StringBuffer.toString:()Ljava/lang/String;
22: areturn
--
Best regards,
Alexey mailto:[EMAIL PROTECTED]
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