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String variable interpolation Java [duplicate]
String building in Java confounds me. I abhore doing things like:
5 Answers
5
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PermGen elimination in JDK 8
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Fixed size at startup – difficult to tune.
Internal Hotspot types were Java objects : Could move with full GC, opaque, not strongly typed and hard to debug, needed meta-metadata.
Simplify full collections : Special iterators for metadata for each collector
Want to deallocate class data concurren...
String.format() to format double in java
...alFormat.setRoundingMode(RoundingMode.UP);
Here are the imports:
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.Locale;
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What's the best way to check if a String represents an integer in Java?
... (c < '0' || c > '9')... are the <= and >= operators faster in Java?
– Anonymous
Oct 26 '08 at 1:43
3
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Can overridden methods differ in return type?
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Java supports* covariant return types for overridden methods. This means an overridden method may have a more specific return type. That is, as long as the new return type is assignable to the return type of the method you ar...
Should I use Java's String.format() if performance is important?
...d + comes ahead of format. by a factor of 5 to 6.
Try it your self
import java.io.*;
import java.util.Date;
public class StringTest{
public static void main( String[] args ){
int i = 0;
long prev_time = System.currentTimeMillis();
long time;
for( i = 0; i< 100000; i++){
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Java optional parameters
How do I use optional parameters in Java? What specification supports optional parameters?
17 Answers
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Does Java casting introduce overhead? Why?
... casting is not feasible, JVM must throw a ClassCastException.
Taken from JavaWorld: The cost of casting
Casting is used to convert between
types -- between reference types in
particular, for the type of casting
operation in which we're interested
here.
Upcast operations (also cal...
Java: Class.this
I have a Java program that looks like this.
5 Answers
5
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Comparing boxed Long values 127 and 128
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TL;DR
Java caches boxed Integer instances from -128 to 127. Since you are using == to compare objects references instead of values, only cached objects will match. Either work with long unboxed primitive values or use .equals() to ...