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How to create custom exceptions in Java? [closed]
How do we create custom exceptions in Java?
3 Answers
3
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Calculate size of Object in Java [duplicate]
...zes of data structures) and it seems like there is no method to do this in Java. Supposedly, C/C++ has sizeOf() method, but this is nonexistant in Java. I tried recording the free memory in the JVM with Runtime.getRuntime().freeMemory() before and after creating the object and then recording the...
Which is more efficient, a for-each loop, or an iterator?
...ew for loop syntax, compare the generated bytecodes from the following two Java snippets. First the for loop:
List<Integer> a = new ArrayList<Integer>();
for (Integer integer : a)
{
integer.toString();
}
// Byte code
ALOAD 1
INVOKEINTERFACE java/util/List.iterator()Ljava/util/Itera...
Get login username in java
How can I get the username/login name in Java?
8 Answers
8
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What causes java.lang.IncompatibleClassChangeError?
I'm packaging a Java library as a JAR, and it's throwing many java.lang.IncompatibleClassChangeError s when I try to invoke methods from it. These errors seem to appear at random. What kinds of problems could be causing this error?
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“java.lang.OutOfMemoryError : unable to create new native Thread”
We are getting "java.lang.OutOfMemoryError : unable to create new native Thread " on 8GB RAM VM after 32k threads (ps -eLF| grep -c java)
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Why do people still use primitive types in Java?
Since Java 5, we've had boxing/unboxing of primitive types so that int is wrapped to be java.lang.Integer , and so and and so forth.
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How to create empty folder in java? [duplicate]
...le you use the .mkdirs() method on a File object: http://www.roseindia.net/java/beginners/java-create-directory.shtml
// Create a directory; all non-existent ancestor directories are
// automatically created
success = (new File("../potentially/long/pathname/without/all/dirs")).mkdirs();
if (!succes...
replace String with another in java
...
Try this:
https://docs.oracle.com/javase/1.5.0/docs/api/java/lang/String.html#replace%28java.lang.CharSequence,%20java.lang.CharSequence%29
String a = "HelloBrother How are you!";
String r = a.replace("HelloBrother","Brother");
System.out.println(r);
This...
Exact difference between CharSequence and String in java [duplicate]
...you pasted: simply compile that, and have a look at the JVM bytecode using javap -v. There you will notice that both obj and str are references to the same constant object. As a String is immutable, this kind of sharing is all right.
The + operator of String is compiled as invocations of various St...