ืคืื ืงืฆืื ืื ืชืืื ื ื ืืืืืื ืืื ืืืืืง ืื ืืืจืืืช 'ืืืืื' ืืืจืืืช ื ืืกืคืช ืื ืื. ืื ืืชื ืืืฉ ืืื, ืืืชืื ืฉืชืฉืชืืฉ ืื ืืื ืืืฆืื 'ืืืืช'. ืืื ืื ืื ืืฉืจืช ืืช ืืืืจื. ืืืืืจ ืื, ื ืชืืืืก ืืืฆื ื ืขืฉื ืฉืืืืฉ, ืืืฉืื ืฉื java.lang.String.contains() ืืืืื ืืจืืืื ืืืืืื ืืืืคืืข ืื ืื ื ืขืฉื ืฉืืืืฉ ืืืืจ.
ืืื ืฉืืืช contains()?
ืืชื ืืืื ืืืฉืชืืฉ ืืฉืืืช contains(String key) ืืื " ืืืฆืื " ืื ืืืจืืืช ืืกืืืืช " ืืคืชื " ืงืืืืช ืืชืื ืืืจืืืช ืืกืืืืช ืื ืื. ืื ื ืืฆื "ืืคืชื", "true" ืืืืืจ. ืืืจืช ืชืงืื "ืฉืงืจ".ืืืฉืื ืคื ืืื
ืฉืืื ืื ืืืจ ืืืืฉืืช ืขื ืืื java.lang.String . ืืชื ืื ืฆืจืื ืืืืฉื ืืช ืื ืืขืฆืื. ืื ื ืืกืืจ ืืืืจ ืขื ืื ืืืื ืชื.public class ContainsMethod
{
public boolean contains(CharSequence key)
{
return indexOf(key.toString()) > -1;
}
}
ืืกืืจ ืงืื
ืฉืืืช contains() ืืืงืืช CharSequence ืืคืจืืืจ ืงืื. ืืฉืจ ืืืืจ ืืืืืจ ืืืชืจ ื"ืืืจืืืช". ืื ืืืืืื ืืื ืืืืฉื indexOf(key.toString()) > -1; . ืืืืืจ, ืื ื"ืืคืชื" ืืื ื ืืฆื ืืืื ืืงืก ืืืฉืื ("0" ืื ืืืชืจ), ืื "true" ืืืืืจ. ืืื ืืืคืชื ืื ื ืืฆื, ืืื "ืฉืงืจ" ืืืืืจ.ืืืฆื ืืืฉืชืืฉ ืืฉืืืช contains()?
ืื ื ืืื ืืชื ืืืื ืืืฉืชืืฉ ืื.public class ContainsMethod {
public static void main(String[] args) {
String input = "A brown fox jumped over a lazy dog.";
// check the containing strings
System.out.println("input.contains(bro) = " + input.contains("bro"));
System.out.println("input.contains(brown) = " + input.contains("brown"));
System.out.println("input.contains(Brown) = " + input.contains("Brown"));
System.out.println("input.contains(fox) = " + input.contains("fox"));
System.out.println("input.contains(xof) = " + input.contains("xof"));
System.out.println("input.contains(dog) = " + input.contains("dog"));
System.out.println("input.contains(lazyy) = " + input.contains("lazyy"));
System.out.println("input.contains(jumping) = " + input.contains("jumping"));
}
}
ืชึฐืคืึผืงึธื
input.contains(bro) = true input.contains(brown) = true input.contains(Brown) = false // false ืื input.contains(fox) ืชืืื-ืจืืฉืืืช = true input.contains(xof) = false // false ืื ืืกืืจ ืฆืจืื ืืืืืช ืืื input.contains(dog) = true input.contains(lazyy) = false // false ืื ืื ื ืืฆืื ืชืช-ืืืจืืืช ืฉืืื input.contains(jumping) = false
ืืกืืจ ืงืื
ืฉืืื ืื, ืฉืืื ืื ืชืืืื ืืืืชืืืช ืืืืืืช ืขืืืจ ืคืจืืืจื ืงืื. ืื ืืงืืข ืื "ื, ืืชื ืืืื ืืจืืืช ืืืฉืจ ืืชื ืืืคืฉ "ืืื" ืืืืืจ true , ืืขืื ืฉ false ืืืืืจ ืขืืืจ "ืืื". ืืื ืื, ืชืงืื ืืืช ืื ืชืืฆื "ืคืืงืก" ื- false ืขืืืจ "xof" ืื "oxf" ืืืืืื ืฉืกืืจ ืืชืืืื ืฆืจืื ืืืืืช ืืื. ืืืกืืฃ, ืื ืชืืฆื "ืงืคืืฆื" ืื "ืงืคืืฆื" ืชืงืื ืืืช ืืืืืื ืฉืื ืืคืจืืืจ ืงืืื ืืืืจืืืช " ืงืื ". ืืขืื ืฉืื ืชืืืืง ืื ืืฉ "ืงืคืืฆื" ืืืืืจ false ืืืืืื ืฉืืืคืชื ืืืื ("ืงืคืืฆื") ืื ื ืืฆื.ืืืคืื ืืืจืืืื
ืฉืืืช java.lang.String.contains() ืืืจืืช ื-Null Pointer Exception ืื ืชืฉืื ืืืชืื ืืช ืืืจืืืช ืืคืจืืืจืื ืขื ืขืจื ืงืื ืงืจืื ืืืฉืื.public class ContainsMethod {
public static void main(String[] args) {
String input = "Here is a test string.";
String test = null;
// check what happens if you look for a null string
System.out.println("input.contains(test) = " + input.contains(test));
}
}
ืชึฐืคืึผืงึธื
Exception in thread "main" java.lang.NullPointerException
at java.lang.String.contains(String.java:2133)
at ContainsMethod.main(ContainsMethod.java:8)
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