/*
Java Search String using indexOf Example
This example shows how we can search a word within a String object using
indexOf method.
*/
public class SearchStringExample {
public static void main(String[] args) {
//declare a String object
String strOrig = "Hello world Hello World";
/*
To search a particular word in a given string use indexOf method.
indexOf method. It returns a position index of a word within the string
if found. Otherwise it returns -1.
*/
int intIndex = strOrig.indexOf("Hello");
if(intIndex == - 1){
System.out.println("Hello not found");
}else{
System.out.println("Found Hello at index " + intIndex);
}
/*
we can also search a word after particular position using
indexOf(String word, int position) method.
*/
int positionIndex = strOrig.indexOf("Hello",11);
System.out.println("Index of Hello after 11 is " + positionIndex);
/*
Use lastIndexOf method to search a last occurrence of a word within string.
*/
int lastIndex = strOrig.lastIndexOf("Hello");
System.out.println("Last occurrence of Hello is at index " + lastIndex);
}
}
/*
Output of the program would be :
Found Hello at index 0
Index of Hello after 11 is 12
Last occurrence of Hello is at index 12
*/
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/*
Java Reverse String Array Example
This Java Reverse String Array example shows how to find sort an array of
String in Java using Arrays and Collections classes.
*/
import java.util.Collections;
import java.util.List;
import java.util.Arrays;
public class ReverseStringArrayExample {
public static void main(String args[]){
//String array
String[] strDays = new String[]{"Sunday", "Monday", "Tuesday", "Wednesday"};
/*
* There are basically two methods, one is to use temporary array and
* manually loop through the elements of an Array and swap them or to use
* Arrays and Collections classes.
*
* This example uses the second approach i.e. without temp variable.
*
*/
//first create a list from String array
List<String> list = Arrays.asList(strDays);
//next, reverse the list using Collections.reverse method
Collections.reverse(list);
//next, convert the list back to String array
strDays = (String[]) list.toArray();
System.out.println("String array reversed");
//print the reversed String array
for(int i=0; i < strDays.length; i++){
System.out.println(strDays[i]);
}
}
}
/*
Output of above given Java Reverse String Array example would be
String array reversed
Wednesday
Tuesday
Monday
Sunday
*/
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import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Scanner;
/*
Java InputStream to String Example
This Java InputStream to String example shows how to convert InputStream to String in Java.
*/
public class ConvertInputStreamToStringExample {
public static void main(String args[]) throws IOException{
//get InputStream of a file
InputStream is = new FileInputStream("c:/data.txt");
String strContent;
/*
* There are several way to convert InputStream to String. First is using
* BufferedReader as given below.
*/
//Create BufferedReader object
BufferedReader bReader = new BufferedReader(new InputStreamReader(is));
StringBuffer sbfFileContents = new StringBuffer();
String line = null;
//read file line by line
while( (line = bReader.readLine()) != null){
sbfFileContents.append(line);
}
//finally convert StringBuffer object to String!
strContent = sbfFileContents.toString();
/*
* Second and one liner approach is to use Scanner class. This is only supported
* in Java 1.5 and higher version.
*/
strContent = new Scanner(is).useDelimiter("\\A").next();
}
}
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/*
Java Date to String Example
This Java Date to String example shows how to convert java.util.Date to
String in Java.
*/
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
public class ConvertDateToStringExample {
public static void main(String args[]){
//create new java.util.Date object
Date date = new Date();
/*
* To convert java.util.Date to String, use SimpleDateFormat class.
*/
/*
* crate new SimpleDateFormat instance with desired date format.
* We are going to use yyyy-mm-dd hh:mm:ss here.
*/
DateFormat dateFormat = new SimpleDateFormat("yyyy-mm-dd hh:mm:ss");
//to convert Date to String, use format method of SimpleDateFormat class.
String strDate = dateFormat.format(date);
System.out.println("Date converted to String: " + strDate);
}
}
/*
Output of above given java.util.Date to String example would be
Date converted to String: 2011-17-10 11:17:50
*/
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/*
Java Convert int Array To String Example
This Java Convert int Array To String example shows how to find convert an array of int
to a String in Java.
*/
import java.util.Arrays;
public class ConvertIntArrayToStringExample {
public static void main(String args[]){
//int array
int[] intNumbers = new int[]{1, 2, 3, 4, 5};
/*
* First approach is to loop through all elements of an int array
* and append them to StringBuffer object one by one. At the end,
* use toString method to convert it to String.
*/
//create new StringBuffer object
StringBuffer sbfNumbers = new StringBuffer();
//define the separator you want in the string. This example uses space.
String strSeparator = " ";
if(intNumbers.length > 0){
//we do not want leading space for first element
sbfNumbers.append(intNumbers[0]);
/*
* Loop through the elements of an int array. Please
* note that loop starts from 1 not from 0 because we
* already appended the first element without leading space.s
*/
for(int i=1; i < intNumbers.length; i++){
sbfNumbers.append(strSeparator).append(intNumbers[i]);
}
}
System.out.println("int array converted to String using for loop");
//finally convert StringBuffer to String using toString method
System.out.println(sbfNumbers.toString());
/*
* Second options is to use Arrays class as given below.
* Use Arrays.toString method to convert int array to String.
*
* However, it will return String like [1, 2, 3, 4, 5]
*/
String strNumbers = Arrays.toString(intNumbers);
System.out.println("String generated from Arrays.toString method: " + strNumbers);
//you can use replaceAll method to replace brackets and commas
strNumbers = strNumbers.replaceAll(", ", strSeparator).replace("[", "").replace("]", "");
System.out.println("Final String: " + strNumbers);
}
}
/*
Output of above given convert int array to String example would be
int array converted to String using for loop
1 2 3 4 5
String generated from Arrays.toString method: [1, 2, 3, 4, 5]
Final String: 1 2 3 4 5
*/
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/*
Java Char Array To String Example
This Java char array to String example shows how to convert char array to
String in Java.
*/
public class CharArrayToStringExample {
public static void main(String args[]){
//char array
char[] charArray = new char[]{'J','a','v','a'};
/*
* To convert char array to String in Java, use
* String(Char[] ch) constructor of Java String class.
*/
String str = new String(charArray);
System.out.println("Char array converted to String: " + str);
}
}
/*
Output of above given char array to String example would be
Char array converted to String: Java
*/
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/*
Java ArrayList to String Array Example
This Java ArrayList to String Array example shows how to convert ArrayList to String array
in Java.
*/
import java.util.ArrayList;
import java.util.Arrays;
public class ArrayListToStringArrayExample {
public static void main(String args[]){
//ArrayList containing string objects
ArrayList<String> aListDays = new ArrayList<String>();
aListDays.add("Sunday");
aListDays.add("Monday");
aListDays.add("Tuesday");
/*
* To convert ArrayList containing String elements to String array, use
* Object[] toArray() method of ArrayList class.
*
* Please note that toArray method returns Object array, not String array.
*/
//First Step: convert ArrayList to an Object array.
Object[] objDays = aListDays.toArray();
//Second Step: convert Object array to String array
String[] strDays = Arrays.copyOf(objDays, objDays.length, String[].class);
System.out.println("ArrayList converted to String array");
//print elements of String array
for(int i=0; i < strDays.length; i++){
System.out.println(strDays[i]);
}
}
}
/*
Output of above given ArrayList to String Array example would be
ArrayList converted to String array
Sunday
Monday
Tuesday
*/
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