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Export Preferences to XML file in Java

Krantik Chavan
Krantik Chavan
Updated on 25-Jun-2020 847 Views

In order to export preferences to an XML file in Java, we need to use the exportSubtree() method. This method emits an XML document showing all of the preferences contained in this node and all of its descendants. This XML document provides an offline backup of the subtree rooted at the node.Declaration − The java.util.prefs.Preferences.exportSubtree method is declared as follows −public abstract void exportSubtree(OutputStream os) throws IOException, BackingStoreExceptionLet us see a program to export preferences to an XML file in Java −import java.io.FileOutputStream; import java.util.prefs.Preferences; public class Example {    public static void main(String args[]) throws Exception {    Preferences ...

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Moving a file from one directory to another using Java

George John
George John
Updated on 25-Jun-2020 6K+ Views

We can use Files.move() API to move file from one directory to another. Following is the syntax of the move method.public static Path move(Path source, Path target, CopyOption... options) throws IOExceptionWheresource − Source path of file to be movedtarget − Target path of file to be movedoptions − options like REPLACE_EXISTING, ATOMIC_MOVEExampleimport java.io.IOException; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; public class Tester {    public static void main(String[] args) {       //move file from D:/temp/test.txt to D:/temp1/test.txt       //make sure that temp1 folder exists       moveFile("D:/temp/test.txt", "D:/temp1/test.txt");    }    private static void moveFile(String ...

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Object Serialization with inheritance in Java

George John
George John
Updated on 25-Jun-2020 3K+ Views

In Serialization when inheritance is introduced then on the basis of superclass and subclass certain cases have been defined which make the understanding of Serialization in each case much simpler. The fundamental rules which should be followed are as below.1. When super class is implements Serializable interface and subclass is not.In this case the object of subclass get serialized by default when superclass get serialize, even if subclass doesn't implements Serializable interface.Examplepublic class TestSerialization {    public static void main(String[] args) throws IOException, ClassNotFoundException {       B obj = new B();       FileOutputStream fos = new ...

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High-level file operations in Python (shutil)

Chandu yadav
Chandu yadav
Updated on 25-Jun-2020 1K+ Views

A number of functions for hgh level operations on files and directories have been defined in shutil module of Python’s standard library.copy()This function copies a file to a specified file in same or other directory. First parameter to the function is a string representation of existing file. Second argument is either name of resultant file or directory. If it is a directory, the file is coped in it with same name. The metadata of original file is not maintained.>>> import shutil >>> shutil.copy("hello.py", "newdir/") 'newdir/hello.py'copy2()This function is similar to copy() function except for the fact that it retains metadata of ...

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POJI in Java

Ankith Reddy
Ankith Reddy
Updated on 25-Jun-2020 611 Views

POJI is an acronym for Plain Old Java Interface which corresponds to a Java standard interface which means that these interfaces are in the context of providing services in JEE. For example, OSGI service is offered through POJI in JEEIn other terms we can say that POJI is an ordinary interface without any specialty that is not inherited from any of the technology API specific interfaces or framework interfaces.Exampleinterface myCustomInterface {    public void myMethod(); } interface mySecondCustomInterface extends myCustomInterface {    public void mySecondMethod(); }Both interfaces would be called as POJI as they do not inherit any technology specific ...

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POJO vs Java Beans

George John
George John
Updated on 25-Jun-2020 5K+ Views

As we know that in Java POJO refers to the Plain old Java object.POJO and Bean class in Java shares some common features which are as follows −Both classes must be public i.e accessible to all.Properties or variables defined in both classes must be private i.e. can't be accessed directly.Both classes must have default constructor i.e no argument constructor.Public Getter and Setter must be present in both the classes in order to access the variables/properties.The only difference between both the classes is Java make java beans objects serialized so that the state of a bean class could be preserved in ...

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Primitive Wrapper Classes are Immutable in Java

Arjun Thakur
Arjun Thakur
Updated on 25-Jun-2020 2K+ Views

In Java Immutable class is a class which once created and it's contents can not be changed.On same concept Immutable objects are the objects whose state can not be changed once constructed.Wrapper classes are made to be immutable due to following advantages −Since the state of the immutable objects can not be changed once they are created they are automatically synchronized.Immutable objects are automatically thread-safe, the overhead caused due to use of synchronisation is avoided.Once created the state of the wrapper class immutable object can not be changed so there is no possibility of them getting into an inconsistent state.The ...

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File and Directory Comparisons in Python

George John
George John
Updated on 25-Jun-2020 6K+ Views

Python’s standard library has filecmp module that defines functions for comparison of files and directories. This comparison takes into consideration the properties of files in addition to data in them.Example codes in this article use following file and directory structure.Two directories dir1 and dir2 are first created under current working directory. They contain following files.--dir1/newfile.txt-- This is a file in dir1 --dir1/file1.txt-- Hello Python --dir1/file2.txt-- Python Standard Library --dir2/file1.txt-- Hello Python --dir2/file2.txt-- Python LibraryLet us now describe various comparison functions in filecmp module.filecmp.cmp(f1, f2, shallow=True)This function compares the two files and returns True if they are identical, False otherwise. The ...

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Prefix sum array in python using accumulate function

karthikeya Boyini
karthikeya Boyini
Updated on 25-Jun-2020 603 Views

Given an array and we have to do the prefix sum array using accumulate function.itertools.accumulate(iterable[, func]) module functions all construct and return iterators. So they should only be accessed by functions or loops that truncate the stream. Make an iterator that returns accumulated sums. Elements may be any addable type including Decimal or Fraction. If the optional function argument is supplied, it should be a function of two arguments and it will be used instead of addition.ExampleInput Data = [1, 0, 2, 3, 5] >>> list(accumulate(data)) # running summation Output [1, 1, 3, 6, 11]AlgorithmStep 1: Create list. Step 2: ...

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How to close or hide the virtual keyboard on Android?

Chandu yadav
Chandu yadav
Updated on 25-Jun-2020 5K+ Views

In Android there are some situations, we should close android default keyboard forcefully. For that this example is help for you.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml.             Step 3Add the following code to src/MainActivity.javaimport android.app.ProgressDialog; import android.os.Build; import android.os.Bundle; import android.os.Handler; import android.support.annotation.RequiresApi; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.view.inputmethod.InputMethodManager; import android.widget.Button; import android.widget.EditText; import android.widget.ProgressBar; public class MainActivity extends AppCompatActivity implements View.OnClickListener {    Handler mHandler;   ...

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