January 2018

Java String contains() method explained with examples

//This will print "true" because "Game" is present in the given String
System.out.println(str.contains("Game"));

/* This will print "false" because "aGme" is not present, the characters
 * must be present in the same sequence as specified in the contains method
 */
System.out.println(str.contains("aGme"));</pre>
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Syntax of contains() method</h2>
<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">public boolean contains(CharSequence str)</pre>
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The return type is boolean which means this method returns true or false. When the character sequence found in the given string then this method returns true else it returns false.</div>
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If the CharSequence is null then this method throws NullPointerException. For example: calling this method like this would throw NullPointerException.</div>
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<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">str.contains(null);</pre>
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Java String contains() method Example</h2>
<div style="background-color: white; box-sizing: border-box; color: #222426; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif; font-size: 17px; margin-bottom: 26px; padding: 0px;">
The second print statement displayed false because the contains() method is case sensitive. You can also use the contains() method for case insensitive check, I have covered this at the end of this tutorial.</div>
<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">class Example{ 
 public static void main(String args[]){ 
 String str = "Do you like watching Game of Thrones"; 
 System.out.println(str.contains("like"));
 
 /* this will print false as the contains() method is
 * case sensitive. Here we have mentioned letter "l" 
 * in upper case and in the actual string we have this
 * letter in the lower case. 
 */
 System.out.println(str.contains("Like")); 
 System.out.println(str.contains("Game")); 
 System.out.println(str.contains("Game of")); 
 }
}</pre>
<div style="background-color: white; box-sizing: border-box; color: #222426; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif; font-size: 17px; margin-bottom: 26px; padding: 0px;">
Output:</div>
<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">true
false
true
true</pre>
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Example 2: Using Java String contains() method in the if-else statement</h2>
<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">class Example{ 
 public static void main(String args[]){ 
 String str = "This is an example of contains()"; 
 /* Using the contains() method in the if-else statements, since
 * this method returns the boolean value, it can be used
 * in the if else conditions whenever needed.
 */
 if(str.contains("example")){
 System.out.println("The word example is found in given string");
 }
 else{
 System.out.println("The word example is not found in the string");
 }
 }
}</pre>
<div style="background-color: white; box-sizing: border-box; color: #222426; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif; font-size: 17px; margin-bottom: 26px; padding: 0px;">
Output:</div>
<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">The word example is found in given string</pre>
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Java String contains() method for case insensitive check</h2>
<div style="background-color: white; box-sizing: border-box; color: #222426; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif; font-size: 17px; margin-bottom: 26px; padding: 0px;">
We have seen above that the contains() method is case sensitive, however with a little trick, you can use this method for case insensitive checks. Lets take an example to understand this:</div>
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Here we are using the <a href="https://beginnersbook.com/2013/12/java-string-tolowercase-method-example/" style="box-sizing: border-box; color: #7dc246; font-weight: bold !important; text-decoration-line: none; transition: all 0.1s ease-in-out;">toLowerCase() method</a> to convert both the strings to lowercase so that we can perform case insensitive check using contains() method. We can also use toUpperCase() method for this same purpose as shown in the example below.</div>
<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">class Example{ 
 public static void main(String args[]){ 
 String str = "Just a Simple STRING"; 
 String str2 = "string";
 //Converting both the strings to lower case for case insensitive checking
 System.out.println(str.toLowerCase().contains(str2.toLowerCase()));
 
 //You can also use the upper case method for the same purpose.
 System.out.println(str.toUpperCase().contains(str2.toUpperCase()));
 }
}</pre>
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Output:</div>
<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">true
true</pre>
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Reference:</h4>
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<a href="https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#contains(java.lang.CharSequence)" rel="noopener" style="box-sizing: border-box; color: #7dc246; font-weight: bold !important; text-decoration-line: none; transition: all 0.1s ease-in-out;" target="_blank">String Contains() method – JavaDoc</a></div>
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Java String contains() method explained with examples

Java String contains() method checks whether a particular string is a part of another string or not. This method returns true if a specif...

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Java – String indexOf() Method Example

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The method <code style="background-color: #eeeeee; box-sizing: border-box; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif;">indexOf()</code> is used for finding out the index of the specified character or substring in a particular String. There are 4 variations of this method: <code style="background-color: #eeeeee; box-sizing: border-box; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif;">int indexOf(int ch)</code>: It returns the index of the first occurrence of character ch in a String. <code style="background-color: #eeeeee; box-sizing: border-box; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif;">int indexOf(int ch, int fromIndex)</code>: It returns the index of first occurrence if character ch, starting from the specified index “fromIndex”. <code style="background-color: #eeeeee; box-sizing: border-box; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif;">int indexOf(String str)</code>: Returns the index of string str in a particular String. <code style="background-color: #eeeeee; box-sizing: border-box; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif;">int indexOf(String str, int fromIndex)</code>: Returns the index of string str, starting from the specified index “fromIndex”.</div>
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All the above variations returns -1 if the specified char/substring is not found in the particular <code style="background-color: #eeeeee; box-sizing: border-box; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif;">String</code>.</div>
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Example</h3>
<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">public class IndexOfExample{
 public static void main(String args[]) {
 String str1 = new String("This is a BeginnersBook tutorial");
 String str2 = new String("Beginners");
 String str3 = new String("Book");
 String str4 = new String("Books");
 System.out.println("Index of B in str1: "+str1.indexOf('B'));
 System.out.println("Index of B in str1 after 15th char:"+str1.indexOf('B', 15));
 System.out.println("Index of B in str1 after 30th char:"+str1.indexOf('B', 30));
 System.out.println("Index of string str2 in str1:"+str1.indexOf(str2));
 System.out.println("Index of str2 after 15th char"+str1.indexOf(str2, 15));
 System.out.println("Index of string str3:"+str1.indexOf(str3));
 System.out.println("Index of string str4"+str1.indexOf(str4));
 System.out.println("Index of harcoded string:"+str1.indexOf("is"));
 System.out.println("Index of hardcoded string after 4th char:"+str1.indexOf("is", 4));
 }
}</pre>
<div style="background-color: white; box-sizing: border-box; color: #222426; font-family: "PT Sans", Arial, "Helvetica Neue", Helvetica, sans-serif; font-size: 17px; margin-bottom: 26px; padding: 0px;">
Output:</div>
<pre class="prettyprint prettyprinted" style="background-color: #eeeeee; box-sizing: border-box; clear: both; color: #222426; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-size: 13px; overflow: auto; padding: 2px;">Index of B in str1: 10
Index of B in str1 after 15th char:19
Index of B in str1 after 30th char:-1
Index of string str2 in str1:10
Index of str2 after 15th char-1
Index of string str3:19
Index of string str4-1
Index of harcoded string:2
Index of hardcoded string after 4th char:5</pre>
</div>

Java – String indexOf() Method Example

The method indexOf() is used for finding out the index of the specified character or substring in a particular String. There are 4 varia...

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ORA-01552: cannot use system rollback segment for non-system tablespace

ORA-01552: cannot use system rollback segment for non-system tablespace

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