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Description
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1/ Try to trim whitespace from only the right side of a
string. This is useful for writing source code editors
where the left hand side whitespace is useful for indenting
the source code, but the right hand side needs none.
2/ java.lang.String.trim() trims both ends of whitespace
3/ What should occur is that java.lang.String.trim() should
use java.lang.String.ltrim() and java.lang.String.rtrim().
======================================================================
Posted Date : 2005-12-23 02:26:28.0
A suggested implementsion submitted by java.net user leouser follows:
A DESCRIPTION OF THE FIX :
ID: 4074696
JDK VERSION: jdk-6-rc-bin-b64-linux-i586-15_dec_2005.bin
NOTE: This RFE is closed because it was thought that the RFE was not compelling enough. I am in disagreement with this and am sending this in. If its 'closedness' is the final word on the matter I will accept this. :)
RATIONAL( embedded in test as well ):
/**
* BUG/RFE ID: 4074696 add rtrim and ltrim
* RATIONALE:
* String has trim(), which is useful in many cases. Yet it is common to
* want to remove the whitespace from only one end of the String.
* There does not appear an obvious way of acheiving this in the String interface
* at this time. The simplest one line solution Ive come up with is to do
* replaceFirst targeting the whitespace of the end or start of the text.
* This probably is not desirable in code that requires high performance.
*
* In Python with a string, you have strip which is equivilent with trim.
* But in Python you also have rstrip and lstrip. These three are simple
* to remember and use.
*
* Hence comes rtrim and ltrim. Their implementations are derived from trim.
* This means that they follow the implementation of trim in their own
* implementation. Being able to work with the char array directly makes
* their implementatins fairly simple.
*
* It should be noted that this BUG ID was closed because it the case was
* not compelling enough for its addition to the API. From my individual usage
* standpoint rtrim and ltrim are compelling to be added.
*
* Ramifications of change:
* 2 new methods added.
* Does not alter any internals in the implementation, calling
* rtrim and ltrim should be safe to call.
* String is final, there will be no subclasses fo String out there.
* To acheive a subclass or modification the user will need to use
* an extralinguistic mechanism. This violates the contract, let them suffer.
* More work in keeping trim, rtrim and ltrim in sync implementation wise.
* I believe it is desirable to use relatively the same code for each implementation.
* Hence if trim is made more efficient, rtrim and ltrim may also gain.
* But they too will need to be changed. Given the shortness of these methods,
* it is questionable that the syncronization process would be cumbersome.
*
* This java.lang.String was modified against:
* jdk-6-rc-bin-b64-linux-i586-15_dec_2005.bin
*
* and also executed on a Suse Linux 7.3 distribution.
*
* Brian Harry
* xxxxx@xxxxx
* Dec 22, 2005
*
*
*/
UNIFIED DIFF:
--- /home/brihar/nstuff/java6/jdk1.6.0/java/lang/String.java Thu Dec 15 02:16:40 2005
+++ /home/brihar/javarefs/java/lang/String.java Thu Dec 22 10:33:57 2005
@@ -2545,6 +2545,87 @@
}
/**
+ * Returns a copy of the string, with trailing whitespace
+ * omitted.
+ * <p>
+ * If this <code>String</code> object represents an empty character
+ * sequence, or the last characters of character sequence
+ * represented by this <code>String</code> object both have codes
+ * greater than <code>'\u0020'</code> (the space character), then a
+ * reference to this <code>String</code> object is returned.
+ * <p>
+ * Otherwise, if there is no character with a code greater than
+ * <code>'\u0020'</code> in the string, then a new
+ * <code>String</code> object representing an empty string is created
+ * and returned.
+ * <p>
+ * Otherwise, let <i>m</i> be the index of the last character in the string whose code
+ * is greater than <code>'\u0020'</code>. A new <code>String</code>
+ * object is created, representing the substring of this string that
+ * begins with the character at index <i>0</i> and ends with the
+ * character at index <i>m</i>-that is, the result of
+ * <code>this.substring( 0, <i>m</i>+1)</code>.
+ * <p>
+ * This method may be used to trim whitespace (as defined above) from
+ * the end of a string.
+ *
+ * @return A copy of this string with trailing white
+ * space removed, or this string if it has no
+ * trailing white space.
+ */
+ public String rtrim(){
+
+ int off = offset;
+ int i = off + count - 1;
+ char[] val = value;
+
+ while( i >= off && val[ i ] <= ' ' ) i--;
+
+ return i != off + count -1 ? substring( 0, i + 1 - off ): this;
+
+ }
+
+ /**
+ * Returns a copy of the string, with leading whitespace
+ * omitted.
+ * <p>
+ * If this <code>String</code> object represents an empty character
+ * sequence, or the leading characters of character sequence
+ * represented by this <code>String</code> object both have codes
+ * greater than <code>'\u0020'</code> (the space character), then a
+ * reference to this <code>String</code> object is returned.
+ * <p>
+ * Otherwise, if there is no character with a code greater than
+ * <code>'\u0020'</code> in the string, then a new
+ * <code>String</code> object representing an empty string is created
+ * and returned.
+ * <p>
+ * Otherwise, let <i>m</i> be the index of the starting character in the string whose code
+ * is greater than <code>'\u0020'</code>. A new <code>String</code>
+ * object is created, representing the substring of this string that
+ * begins with the character at index <i>m</i>, the result of this
+ * <code>this.substring( <i>m</i> )</code>.
+ * <p>
+ * This method may be used to trim whitespace (as defined above) from
+ * the start of a string.
+ *
+ * @return A copy of this string with leading white
+ * space removed, or this string if it has no
+ * trailing white space.
+ */
+ public String ltrim(){
+
+ int len = count;
+ int i = 0;
+ char[] val = value;
+
+ while( i < len && val[ i ] <= ' ' ) i++;
+
+ return i != 0 ? substring( i ): this;
+
+ }
+
+ /**
* This object (which is already a string!) is itself returned.
*
* @return the string itself.
JUnit TESTCASE :
import junit.framework.TestCase;
import junit.textui.TestRunner;
import static java.lang.System.out;
/**
* BUG/RFE ID: 4074696 add rtrim and ltrim
* RATIONALE:
* String has trim(), which is useful in many cases. Yet it is common to
* want to remove the whitespace from only one end of the String.
* There does not appear an obvious way of acheiving this in the String interface
* at this time. The simplest one line solution Ive come up with is to do
* replaceFirst targeting the whitespace of the end or start of the text.
* This probably is not desirable in code that requires high performance.
*
* In Python with a string, you have strip which is equivilent with trim.
* But in Python you also have rstrip and lstrip. These three are simple
* to remember and use.
*
* Hence comes rtrim and ltrim. Their implementations are derived from trim.
* This means that they follow the implementation of trim in their own
* implementation. Being able to work with the char array directly makes
* their implementatins fairly simple.
*
* It should be noted that this BUG ID was closed because it the case was
* not compelling enough for its addition to the API. From my individual usage
* standpoint rtrim and ltrim are compelling to be added.
*
* Ramifications of change:
* 2 new methods added.
* Does not alter any internals in the implementation, calling
* rtrim and ltrim should be safe to call.
* String is final, there will be no subclasses fo String out there.
* To acheive a subclass or modification the user will need to use
* an extralinguistic mechanism. This violates the contract, let them suffer.
* More work in keeping trim, rtrim and ltrim in sync implementation wise.
* I believe it is desirable to use relatively the same code for each implementation.
* Hence if trim is made more efficient, rtrim and ltrim may also gain.
* But they too will need to be changed. Given the shortness of these methods,
* it is questionable that the syncronization process would be cumbersome.
*
* This java.lang.String was modified against:
* jdk-6-rc-bin-b64-linux-i586-15_dec_2005.bin
*
* and also executed on a Suse Linux 7.3 distribution.
*
* Brian Harry
* xxxxx@xxxxx
* Dec 22, 2005
*
*
*/
public class StringTrimTest extends TestCase{
public StringTrimTest( String test ){
super( test );
}
public void testRtrim(){
out.println();
out.println( "Testing rtrim. expecting one failure" );
String test1 = " GGGG V ";
String shouldbe1 = " GGGG V";
assertEquals( "RtrimTest not equal", test1.rtrim() , shouldbe1 );
String test2 = " ";
String shouldbe2 = "";
assertEquals( "RtrimTest2 not equal", test2.rtrim(), shouldbe2 );
String test3 = "";
String shouldbe3 = "";
assertEquals( "RtrimTest3 not equal", test3.rtrim(), shouldbe3 );
String test4 = "\t\t\t";
String shouldbe4 = "";
assertEquals( "RtrimTest4 not equal", test4.rtrim(), shouldbe4 );
String test5 = "\t\t\t\t ";
String shouldbe5 = "";
assertEquals( "RtrimTest5 not equal", test5.rtrim(), shouldbe5 );
/// should always fail:
out.println( "THIS NEXT TEST IN RTRIM SHOULD FAIL!" );
String test6 = "\t\t\t ";
String shouldbe6 = " ";
assertEquals( "RtrimTest6 not equal", test6.rtrim(), shouldbe6 );
}
public void testLtrim(){
out.println();
out.println( "Testing ltrim. expecting one failure" );
String test1 = " GGGG V ";
String shouldbe1 = "GGGG V ";
assertEquals( "LtrimTest not equal", test1.ltrim() , shouldbe1 );
String test2 = " ";
String shouldbe2 = "";
assertEquals( "LtrimTest2 not equal", test2.ltrim(), shouldbe2 );
String test3 = "";
String shouldbe3 = "";
assertEquals( "LtrimTest3 not equal", test3.ltrim(), shouldbe3 );
String test4 = "\t\t\t";
String shouldbe4 = "";
assertEquals( "LtrimTest4 not equal", test4.ltrim(), shouldbe4 );
String test5 = "\t\t\t\t ";
String shouldbe5 = "";
assertEquals( "LtrimTest5 not equal", test5.ltrim(), shouldbe5 );
/// should always fail:
out.println( "THIS NEXT TEST IN LTRIM SHOULD FAIL!" );
String test6 = "\t\t\t ";
String shouldbe6 = " ";
assertEquals( "LtrimTest6 not equal", test6.ltrim(), shouldbe6 );
}
public static void main( String[] args ){
out.println( "Testing rtrim..." );
TestRunner.run( new StringTrimTest( "testRtrim" ) );
out.println( "Testing ltrim..." );
TestRunner.run( new StringTrimTest( "testLtrim" ) );
}
}
FIX FOR BUG NUMBER:
4074696
Posted Date : 2005-12-23 02:26:28.0
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