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Java Articles
Page 442 of 450
Differences between & and && operators in Java.
& is a bitwise operator and compares each operand bitwise.It is a binary AND Operator and copies a bit to the result if it exists in both operands.Assume integer variable A holds 60 and variable B holds 13 then (A & B) will give 12 which is 0000 1100.Whereas && is a logical AND operator and operates on boolean operands. If both the operands are true, then the condition becomes true otherwise it is false. Assume boolean variable A holds true and variable B holds false then (A && B) is false.& is to be used during bitwise operations and && is useful during logical operations.
Read Morehow to convert Object array to String array in java
As list.toArray() returns an Object[], it can be converted to String array by passing the String[] as parameter. See the example below.import java.util.ArrayList; import java.util.List; public class Tester { public static void main(String[] args) { List data = new ArrayList(); data.add("A"); data.add("B"); data.add("C"); //Object[] objects = data.toArray(); String[] strObjects = data.toArray(new String[0]); for(String obj: strObjects) { System.out.println(obj); } } }OutputA B C
Read Moreremove null value from a String array in Java
Following program creates an array with null values. Convert it a list with not-null values only and then get the array of that list.Exampleimport java.util.ArrayList; import java.util.List; public class Tester { public static void main(String[] args) { String[] array = {"I", null, "love", null, "Java" }; List values = new ArrayList(); for(String data: array) { if(data != null) { values.add(data); } } String[] target = values.toArray(new String[values.size()]); for(String data: target) { System.out.println(data + " "); } } }OutputI love Java
Read MoreHow to convert List<Integer> to int[] in Java?
You can simply iterate through list and fill the array as shown below −import java.util.ArrayList; import java.util.List; public class Tester { public static void main(String[] args) { List list = new ArrayList(); list.add(new Integer(1)); list.add(new Integer(2)); list.add(new Integer(3)); list.add(new Integer(4)); int[] array = new int[list.size()]; for(int i=0;i
Read MoreJava string concat() method vs "+" operator
The notable differences between concat() method and +operator are:concat() method+operatorYou cannot concat a null value to a String using the concat() method.You can concat null value using the ‘+’ operator.Using the concat() method you can concat only two String variables.Using the ‘+’ operator you can concat multiple values.Using the concat() method you can concat only String type of arguments.Using the ‘+’ operator you can concat any type of arguments.
Read MoreWhat is string constant pool in Java?
When you store a String asString str1 = "Hello";directly, then JVM creates a String object with the given value in a separate block of memory known as String constant pool.And whenever we try to create another String asString str2 = "Hello";JVM verifies whether any String object with the same value exists in the String constant pool, if so, instead of creating a new object JVM assigns the reference of the existing object to the new variable.And when we store String asString str = new String("Hello");using the new keyword, a new object with the given value is created irrespective of the ...
Read MoreChecking for Null or Empty or White Space Only String in Java.
We can verify whether the given string is empty using the isEmpty() method of the String class. This method returns true only if length() is 0. Example import java.lang.*; public class StringDemo { public static void main(String[] args) { String str = "tutorialspoint"; // prints length of string System.out.println("length of string = " + str.length()); // checks if the string is empty or not System.out.println("is this string empty? = " + str.isEmpty()); } } Output length of string = 14 is this string empty? = false
Read MoreConstructors of StringBuilder class in Java.
The StringBuilder class of the java.lang package is a mutable sequence of characters. This provides an API compatible with StringBuffer, but with no guarantee of synchronization. Following are the list of constructors provided by the StringBuilder class.S.N.Constructor & Description1StringBuilder()This constructs a string builder with no characters in it and an initial capacity of 16 characters.2StringBuilder(CharSequence seq)This constructs a string builder that contains the same characters as the specified CharSequence.3StringBuilder(int capacity)This constructs a string builder with no characters in it and an initial capacity specified by the capacity argument.4StringBuilder(String str)This constructs a string builder initialized to the contents of the specified string. ...
Read MoreDifference between StringBuffer and StringBuilder.
The StringBuffer and StringBuilder classes are used when there is a necessity to make a lot of modifications to Strings of characters.Unlike Strings, objects of type StringBuffer and String builder can be modified over and over again without leaving behind a lot of new unused objects.The StringBuilder class was introduced as of Java 5 and the main difference between the StringBuffer and StringBuilder is that StringBuilder’s methods are not thread safe (not synchronized).It is recommended to use StringBuilder whenever possible because it is faster than StringBuffer. However, if the thread safety is necessary, the best option is StringBuffer objects.
Read MoreConstructors of StringTokenizer class in Java.
Following are the important constructors of the StringTokenizer class.Sr.No.Constructor & Description1StringTokenizer(String str)This constructor a string tokenizer for the specified string.2StringTokenizer(String str, String delim)This constructor constructs string tokenizer for the specified string.3StringTokenizer(String str, String delim, boolean returnDelims)This constructor constructs a string tokenizer for the specified string.
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