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이해와 활용: 자바 문자열 클래스의 모든 것

이 문서에서는 자바의 문자열(String) 클래스에 대한 기본적인 이해와 다양한 활용 방법을 소개합니다. 문자열 클래스는 자바에서 매우 중요한 역할을 하며, 여러 유용한 메서드를 제공합니다. 이 글에서는 문자열의 생성, 자르기, 대소문자 변환, 연결, 비교 등 여러 기능을 코드 예제와 함께 설명합니다. 이를 통해 자바 프로그래밍에서 문자열을 효과적으로 사용할 수 있는 방법을 배울 수 있습니다.

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이해와 활용: 자바 문자열 클래스의 모든 것

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  1. การโปรแกรมเชิงวัตถุด้วยภาษา JAVA String Class มหาวิทยาลัยเนชั่น http://www.nation.ac.th บุรินทร์ รุจจนพันธุ์ . ปรับปรุง 21 มิถุนายน 2550

  2. ความหมายของ String String เป็น Class ที่ถูกเรียกเข้ามาใช้ในจาวาทันที มี Method ที่น่าใช้มากมาย และไม่ต้อง Import เข้าไปเหมือน Class อื่น เพราะ extends Object เข้ามา public final class String ข้อมูลจาก http://www.yonok.ac.th/pmy/j2sdk-1_4_2-doc.zip ข้อมูลจาก http://yn1.yonok.ac.th/burin/javadocs/api/java/lang/String.html

  3. ตัวอย่างการใช้ String DOS>java x aa class x { public static void main(String args[]){ System.out.println(args[0]); //aa } } class y { public static void main(String[] a){ System.out.println(a.length); } }

  4. String คือ Array of Character String x = "abc"; char data[] = {'a','b','c'}; String y = new String(data);

  5. การใช้ String 5 แบบอย่างง่าย 1. System.out.println("abc"); 2. String cde = "cde"; 3. System.out.println("abc" + cde); 4. String c = "abc".substring(2,3); 5. String d = cde.substring(1,2); First Started at 0 Last Started at 1

  6. พิมพ์ใหญ่ พิมพ์เล็ก และ Substring String z ="ThaiAll"; System.out.println("string = " + z); System.out.println(z.substring(0,4)); // Thai System.out.println(z.substring(2,5)); // aiA System.out.println(z.substring(4)); // All System.out.println(z.toUpperCase()); // THAIALL System.out.println(z.toLowerCase()); // thaiall

  7. พิมพ์ 1 ถึง 10 และ 10 ถึง 1 for(int I=1;I<=10;I++){ System.out.println(I); } for(int I=10;I>=1;I--){ System.out.println(I); }

  8. ตัดตัวอักษรออกมาจากข้อความ (subString) class x{ public static void main(String[] a){ String s = "abcd"; for(int I=0;I<s.length();I++){ System.out.print(s.substring(I,I+1)); } } } Output abcd

  9. String เป็น Array of Char (toCharArray) class x{ public static void main(String[] a){ String s = "abcd"; char ar[]; ar = s.toCharArray(); for(int I=0;I<ar.length;I++){ System.out.print(ar[I]); } } } Output abcd

  10. ตัดข้อความตามตำแหน่ง (subSequence) Returns a new character sequence that is a subsequence of this sequence. class x{ public static void main(String[] a){ String s = "burin and thaiall"; //17 int ln = s.length() - 3; System.out.println(s.subSequence(2,ln)); } } Output rin and thai

  11. แยกข้อความออกจากกัน (split) class x{ public static void main(String[] a){ String s = "cat dog boy"; String ar[] = s.split(" "); for(int I=0;I<ar.length;I++){ System.out.print(ar[I]); } } } Output catdogboy

  12. แทนที่ช่องว่างด้วยคอมม่า (replace) class x{ public static void main(String[] a){ String s = "cat dog boy"; String n = s.replace(' ',','); System.out.print(n); } } Output cat,dog,boy

  13. ต่อข้อความเข้าด้วยกัน (concat) class x{ public static void main(String[] a){ String s = "boy"; String n = s.concat("dog"); n = n + "cat"; System.out.print(n); } } Output boydogcat

  14. เปรียบเทียบ (equals) class x{ public static void main(String[] a){ String s = "cat"; if (s.equals("cat")) System.out.print(1); if (s.equalsIgnoreCase("CAT")) System.out.print(2); } } Output 12

  15. ดึงตัวอักษรจากข้อความ (charAt) class x{ public static void main(String[] a){ String s = "abcd"; char c = s.charAt(2); System.out.print(s.charAt(0)); System.out.print(s.charAt(1) + 0); System.out.print(c); } } Output a98c

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