In this article, we will discuss to check whether particular character sequence exists or not in the invoking string content/value
1. String’s contains(CharSequence str):
- This String method examines whether particular character sequence present in the invoking string content/value or NOT
- And respectively returns a boolean-value either true or false
1.1 Method Signature:
public boolean contains(CharSequence s);
1.2 Returns:
Returns a boolean value either true or false
- True –> if character sequence exists in the invoking-string
- False –> if character sequence is not exists in the invoking-string
1.3 Throws:
- String’s contains() method throws NullPointerException, if character sequence supplied/passed is NULL
2. Examples on String.contains() method:
2.1 Checking whether character sequence exists or NOT
StringContainsMethod.java
package in.bench.resources.string.methods;
public class StringContainsMethod {
public static void main(String[] args) {
String str1 = "Welcome to BenchResources.Net weblog";
// search 1: searching char-value present
boolean search1 = str1.contains("BenchRes");
// printing to console
System.out.println(search1);
// search 2: searching char-value not exists
boolean search2 = str1.contains("tech weblog");
// printing to console
System.out.println(search2);
}
}
Output:
true
false
2.2 Exception scenario by passing NULL value
StringContainsMethod.java
package in.bench.resources.string.methods;
public class StringContainsMethod {
public static void main(String[] args) {
String str1 = "Welcome to BenchResources.Net weblog";
// search 1: searching NULL value
boolean search1 = str1.contains(null);
// printing to console
System.out.println(search1);
}
}
Output:
Exception in thread "main" java.lang.NullPointerException
at java.lang.String.contains(String.java:2076)
at in.bench.resources.string.methods.StringContainsMethod
.main(StringContainsMethod.java:10)
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References:
- https://docs.oracle.com/javase/tutorial/essential/concurrency/immutable.html
- https://docs.oracle.com/javase/tutorial/essential/concurrency/imstrat.html
- https://docs.oracle.com/javase/tutorial/java/data/strings.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/String.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/class-use/String.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/StringBuffer.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html
Happy Coding !!
Happy Learning !!