Name: jl125535 Date: 04/13/2004


A DESCRIPTION OF THE REQUEST :
java.lang.StringBuffer should have a append(String, int start, int length) method to avoid creating temporary Strings or CharSequence objects.

JUSTIFICATION :
I've a code block that needs to build new strings from parts of other strings that wastes 30Kbyte of memory (that gets collected by the GC) to construct ~1000 Strings.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
  To be able to write the test program like this:

NOTE: " Hallo " and " Welt " are only place holders for String objects in the real application.

public class Test {
  public static void main(String[] args) {
    for(int i=0 ; i<1000 ; ++i) {
       StringBuffer sb = new StringBuffer();
       sb.append(" Hallo ", 1, 5);
       sb.append(" Welt ", 0, 5);
       System.out.println(sb.toString() );
    }
  }
}
ACTUAL -
The line from the hprof run:

TRACE 242:
Test.main(Test.java:4)
TRACE 245:
java.lang.String.substring(String.java:1446)
Test.main(Test.java:5)
TRACE 247:
java.lang.String.substring(String.java:1446)
Test.main(Test.java:6)
TRACE 249:
java.lang.StringBuffer.toString(StringBuffer.java:1256)
Test.main(Test.java:7)

          percent live alloc'ed stack class
 rank self accum bytes objs bytes objs trace name
    1 55.29% 55.29% 601448 220 601448 220 1 [I
    2 8.83% 64.12% 96000 2000 96000 2000 250 java.nio.HeapCharBuffer
    3 5.91% 70.03% 64304 431 64304 431 1 [C
    4 4.41% 74.44% 48000 1000 48000 1000 243 [C
    5 4.18% 78.62% 45416 214 45416 214 1 [B
    6 2.21% 80.83% 24000 1000 24000 1000 249 java.lang.String
    7 2.21% 83.03% 24000 1000 24000 1000 247 java.lang.String
    8 2.21% 85.24% 24000 1000 24000 1000 245 java.lang.String
    9 2.21% 87.45% 24000 1000 24000 1000 242 java.lang.StringBuffer


---------- BEGIN SOURCE ----------
public class Test {
  public static void main(String[] args) {
    for(int i=0 ; i<1000 ; ++i) {
       StringBuffer sb = new StringBuffer();
       sb.append(" Hallo ".substring(1, 5));
       sb.append(" Welt ".substring(0, 5));
       System.out.println(sb.toString() );
    }
  }
}
---------- END SOURCE ----------
(Incident Review ID: 250048)
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