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authorAndrew Gallasch <andrewgallasch@gmail.com>2016-10-27 09:50:16 +1030
committerGitHub <noreply@github.com>2016-10-27 09:50:16 +1030
commitbb504b97ca06322cc131105647943f0140d6e313 (patch)
tree99bdab9b3887d2c8cd36748ec9f5d060aab29dce
parenta0978c90d62156ed4bb062a4e84a6f9df16527de (diff)
Add StringBuilder usage tip
-rw-r--r--java.html.markdown15
1 files changed, 14 insertions, 1 deletions
diff --git a/java.html.markdown b/java.html.markdown
index 6487d862..6753b358 100644
--- a/java.html.markdown
+++ b/java.html.markdown
@@ -190,7 +190,20 @@ public class LearnJava {
builderConcatenated.append("the StringBuilder class.");
System.out.println(builderConcatenated.toString()); // only now is the string built
// Output: You can use the StringBuilder class.
-
+
+ // StringBuilder is efficient when the fully constructed String is not required until the end of some processing.
+ StringBuilder stringBuilder = new StringBuilder();
+ String inefficientString = "";
+ for(int i = 0 ; i < 10; i++){
+ stringBuilder.append(i).append(" ");
+ inefficientString += i + " ";
+ }
+ System.out.println(inefficientString);
+ System.out.println(stringBuilder.toString());
+ // inefficientString requires a lot more work to produce, as it generates a String on every loop iteration.
+ // Simple concatenation with + is compiled to a StringBuilder and toString()
+ // Avoid string concatenation in loops.
+
// #3 - with String formatter
// Another alternative way to create strings. Fast and readable.
String.format("%s may prefer %s.", "Or you", "String.format()");