1. Java 문자열 indexOf()
Java의 indexOf() 메소드는 주어진 문자열 내에서 문자 또는 하위 문자열이 처음 나타나는 위치를 반환한다. 문자나 부분 문자열을 찾을 수 없으면 메서드는 -1을 반환한다.
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| public int indexOf(int ch)
public int indexOf(int ch, int fromIndex)
public int indexOf(String str)
public int indexOf(String str, int fromIndex)
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2. 문자열에서 문자 위치 찾기
문자열에서 문자 ‘o’의 위치를 찾으려면 다음 코드를 사용한다.
1) indexOf(int ch)
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| public static void main(String[] args) {
String str = "Hello, world!";
int position = str.indexOf('o');
System.out.println("Position of 'o' in the string is: " + position);
}
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| Position of 'o' in the string is: 4
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2) indexOf(int ch, int fromIndex)
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| public static void main(String[] args) {
String str = "Hello, world!";
int position = str.indexOf('o');
while (position >= 0) {
System.out.println("'o' found at position " + position);
position = str.indexOf('o', position + 1);
}
}
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| 'o' found at position 4
'o' found at position 8
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3) indexOf(String str)
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| public static void main(String[] args) {
String str = "Java is a popular programming language";
int position = str.indexOf("programming");
System.out.println("Position of 'programming' in the string is: " + position);
}
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| Position of 'programming' in the string is: 18
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4) indexOf(String str, int fromIndex)
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| public static void main(String[] args) {
String str = "Java is a popular programming language. Java is widely used in web development.";
int position = -1;
while ((position = str.indexOf('a', position + 1)) != -1) {
System.out.println("Found 'a' at position: " + position);
}
while ((position = str.indexOf("Java", position + 1)) != -1) {
System.out.println("Found 'Java' at position: " + position);
}
}
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| Found 'a' at position: 1
Found 'a' at position: 3
Found 'a' at position: 8
Found 'a' at position: 15
Found 'a' at position: 23
Found 'a' at position: 31
Found 'a' at position: 35
Found 'a' at position: 41
Found 'a' at position: 43
Found 'Java' at position: 0
Found 'Java' at position: 40
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