De Java String-klasse vervangen() methode retourneert een tekenreeks die alle oude char of CharSequence vervangt door een nieuwe char of CharSequence.
Sinds JDK 1.5 is een nieuwe Replace()-methode geïntroduceerd waarmee we een reeks char-waarden kunnen vervangen.
Handtekening
Er zijn twee typen Replace()-methoden in de Java String-klasse.
public String replace(char oldChar, char newChar) public String replace(CharSequence target, CharSequence replacement)
De tweede methode Replace() is toegevoegd sinds JDK 1.5.
Parameters
oudChar : oud karakter
nieuwChar : nieuw karakter
doel : doelreeks karakters
vervanging : vervangende reeks tekens
Geeft terug
vervangen string
Uitzondering gooit
NullPointerException: als de vervanging of het doel gelijk is aan nul.
Interne implementatie
public String replace(char oldChar, char newChar) { if (oldChar != newChar) { int len = value.length; int i = -1; char[] val = value; /* avoid getfield opcode */ while (++i <len) { if (val[i]="=" oldchar) break; } (i < len) char buf[]="new" char[len]; for (int j="0;" i; j++) buf[j]="val[j];" while c="val[i];" buf[i]="(c" =="oldChar)" ? newchar : c; i++; return new string(buf, true); this; pre> <pre> public String replace(CharSequence target, CharSequence replacement) { return Pattern.compile(target.toString(), Pattern.LITERAL).matcher( this).replaceAll(Matcher.quoteReplacement(replacement.toString())); } </pre> <h2>Java String replace(char old, char new) method example</h2> <p> <strong>FileName:</strong> ReplaceExample1.java</p> <pre> public class ReplaceExample1{ public static void main(String args[]){ String s1='javatpoint is a very good website'; String replaceString=s1.replace('a','e');//replaces all occurrences of 'a' to 'e' System.out.println(replaceString); }} </pre> <span> Test it Now </span> <p> <strong>Output:</strong> </p> <pre> jevetpoint is e very good website </pre> <h2>Java String replace(CharSequence target, CharSequence replacement) method example</h2> <p> <strong>FileName:</strong> ReplaceExample2.java</p> <pre> public class ReplaceExample2{ public static void main(String args[]){ String s1='my name is khan my name is java'; String replaceString=s1.replace('is','was');//replaces all occurrences of 'is' to 'was' System.out.println(replaceString); }} </pre> <span> Test it Now </span> <p> <strong>Output:</strong> </p> <pre> my name was khan my name was java </pre> <h2>Java String replace() Method Example 3</h2> <p> <strong>FileName:</strong> ReplaceExample3.java</p> <pre> public class ReplaceExample3 { public static void main(String[] args) { String str = 'oooooo-hhhh-oooooo'; String rs = str.replace('h','s'); // Replace 'h' with 's' System.out.println(rs); rs = rs.replace('s','h'); // Replace 's' with 'h' System.out.println(rs); } }</pre> <p> <strong>Output:</strong> </p> <pre>oooooo-ssss-oooooo oooooo-hhhh-oooooo </pre> <h2>Java String replace() Method Example 4</h2> <p>The replace() method throws the NullPointerException when the replacement or target is null. The following example confirms the same.</p> <p> <strong>FileName:</strong> ReplaceExample4.java</p> <pre> public class ReplaceExample4 { // main method public static void main(String argvs[]) { String str = 'For learning Java, JavaTpoint is a very good site.'; int size = str.length(); System.out.println(str); String target = null; // replacing null with JavaTpoint. Hence, the NullPointerException is raised. str = str.replace(target, 'JavaTpoint '); System.out.println(str); } } </pre> <p> <strong>Output:</strong> </p> <pre> For learning Java, JavaTpoint is a very good site. Exception in thread 'main' java.lang.NullPointerException at java.base/java.lang.String.replace(String.java:2142) at ReplaceExample4.main(ReplaceExample4.java:12) </pre> <hr></len)> Voorbeeld van Java String Replace(char old, char new)-methode
Bestandsnaam: VervangVoorbeeld1.java
public class ReplaceExample1{ public static void main(String args[]){ String s1='javatpoint is a very good website'; String replaceString=s1.replace('a','e');//replaces all occurrences of 'a' to 'e' System.out.println(replaceString); }} Test het nu Uitgang:
jevetpoint is e very good website
Voorbeeld van de methode Java String Replace (CharSequence-doel, CharSequence-vervanging).
Bestandsnaam: VervangVoorbeeld2.java
wat betekent xdxd
public class ReplaceExample2{ public static void main(String args[]){ String s1='my name is khan my name is java'; String replaceString=s1.replace('is','was');//replaces all occurrences of 'is' to 'was' System.out.println(replaceString); }} Test het nu Uitgang:
my name was khan my name was java
Java-tekenreeks vervangen() Methode Voorbeeld 3
Bestandsnaam: VervangVoorbeeld3.java
public class ReplaceExample3 { public static void main(String[] args) { String str = 'oooooo-hhhh-oooooo'; String rs = str.replace('h','s'); // Replace 'h' with 's' System.out.println(rs); rs = rs.replace('s','h'); // Replace 's' with 'h' System.out.println(rs); } } Uitgang:
oooooo-ssss-oooooo oooooo-hhhh-oooooo
Java-tekenreeks vervangen() Methode Voorbeeld 4
De methode Replace() genereert de NullPointerException wanneer de vervanging of het doel null is. Het volgende voorbeeld bevestigt hetzelfde.
Bestandsnaam: VervangVoorbeeld4.java
public class ReplaceExample4 { // main method public static void main(String argvs[]) { String str = 'For learning Java, JavaTpoint is a very good site.'; int size = str.length(); System.out.println(str); String target = null; // replacing null with JavaTpoint. Hence, the NullPointerException is raised. str = str.replace(target, 'JavaTpoint '); System.out.println(str); } } Uitgang:
For learning Java, JavaTpoint is a very good site. Exception in thread 'main' java.lang.NullPointerException at java.base/java.lang.String.replace(String.java:2142) at ReplaceExample4.main(ReplaceExample4.java:12)