Strings are used for storing text.
A String variable contains a collection of characters surrounded by double quotes:
String greeting = "Hello";
A String in Java is actually an object, which contain methods that can perform certain operations on strings. For example, the length of a string can be found with the length() method:
String txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
System.out.println("The length of the txt string is: " + txt.length());
There are many string methods available, for example toUpperCase() and toLowerCase()
String txt = "Hello World";
System.out.println(txt.toUpperCase()); // Outputs "HELLO WORLD"
System.out.println(txt.toLowerCase()); // Outputs "hello world"
The indexOf() method returns the index (the position) of the first occurrence of a specified text in a string (including whitespace)
String txt = "Please locate where 'locate' occurs!";
System.out.println(txt.indexOf("locate")); // Outputs 7
String Concatenation
package com.java.basic;
public class Ch5StringConcatenation {
public static void main(String[] args) {
// TODO Auto-generated method stub
String s1 = "1" + "2";
System.out.println(s1); //prints 12
String s2 = "1" + 2;
System.out.println(s2); //prints 12
String s3 = "1" + 2 + 3;
System.out.println(s3); //prints 123
String s4 = "ABC" + "DEF" + "GHI";
System.out.println(s4); //prints ABCDEFGHI
}
}
Special Character in Strings
The sequence \" inserts a double quote in a string
String txt = "We are the so-called \"Vikings\" from the north.";
The sequence \' inserts a single quote in a string:
String txt = "It\'s alright.";
The sequence \\ inserts a single backslash in a string:
String txt = "The character \\ is called backslash.";
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