์๋ฐ์์ ๋ฌธ์์ด ์์ฑ ๋ฐฉ๋ฒ 2๊ฐ์ง
String str1 = "Hello";
String str2 = new String("Hello");
๋ฌธ์์ด ๋ถ์ด๋ ๋ฐฉ๋ฒ
String result = str1 + " " + str2;
System.out.println(result);
**** ๋ฌธ์์ด์ ์ซ์๋ก ๋ฐ๊พธ๋ ๋ฐฉ๋ฒ ****
String str3 = "317";
int a = Integer.valueOf(str3).intValue(); //๋ฐฉ๋ฒ 1
System.out.println(a + 10);
a = Integer.parseInt(str3); //๋ฐฉ๋ฒ 2
System.out.println(a + 10);
String str4 = "3.17";
double b = Double.valueOf(str4).doubleValue(); //๋ฐฉ๋ฒ 1
System.out.println(b + 10);
b = Double.parseDouble(str4); //๋ฐฉ๋ฒ 2
System.out.println(b + 10);
**** ์ซ์๋ฅผ ๋ฌธ์์ด๋ก ๋ฐ๊พธ๋ ๋ฐฉ๋ฒ ****
int k = 365;
String data = String.valueOf(k); // ๋ฐฉ๋ฒ 1
double j = 3;
data = String.valueOf(j);
System.out.println("" + k); //๋ฐฉ๋ฒ 2 ๋น์ด์๋ ๋ฌธ์์ด์ ๋ถ์ฌ์ฃผ๊ธฐ
System.out.println("" + j);
๋ฌธ์์ด ๊ด๋ จ ํจ์๋ค
String data1 = "abc";
๋ฌธ์์ด์ ํฉ์ณ์ฃผ๋ ํจ์ .concat()
System.out.println(data1.concat("hello"));
๋ฌธ์์ด ๊ธธ์ด ๊ตฌํ๋ ํจ์ .length()
System.out.println(data1.length());
๋ฌธ์์ด ์ฌ๋ผ์ด์ฑ ํ๋ ํจ์ .substring()
// 7๋ฒ์งธ ๋ถํฐ 10๋ฒ์งธ ๊น์ง ๊ฐ์ ธ์ค์์ค
data1 = "hello world";
System.out.println(data1.substring(6, 9+1));
๋ฌธ์์ด์ ๋ถ๋ฆฌํ๋ ํจ์ .split()
data1 = "red, blue, white";
String[] strArray = data1.split(", "); //ํ์ด์ฌ์ ๋ฆฌ์คํธ๋ก ์ฃผ์ง๋ง, ์๋ฐ์ ๊ธฐ๋ณธ์ ๋ฐฐ์ด์ด๋ค.
๋ฌธ์์ด์ ์ผ์ชฝ ๋์ด๋ ์ค๋ฅธ์ชฝ ๋์ ๋ถ์ด์๋ ๊ณต๋ฐฑ ์ ๊ฑฐํ๋ ํจ์ .trim()
data1 = " abc@naver.com";
String data2 = "abc@naver.com";
System.out.println(data1 == data2); //False
System.out.println(data1.trim());
๋ชจ๋ ๋๋ฌธ์๋ก ๋ณํ .toUpperCase()
System.out.println(data2.toUpperCase());
๋ชจ๋ ์๋ฌธ์๋ก ๋ณํ .toLowerCase()
System.out.println(data2.toLowerCase());
ํน์ ๋ฌธ์์ด์ด ์ด๋์ ์๋์ง(์ธ๋ฑ์ค) ์๋ ค์ฃผ๋ ํจ์ .indexOf()
String data2 = "abc@naver.com";
System.out.println(data2.indexOf("@"));
System.out.println(data2.indexOf("naver"));
System.out.println(data2.toUpperCase().indexOf("NAVER"));
๋ฌธ์์ด์ ํฌ๊ธฐ ๋น๊ต! (์๋, ๊ฐ๋, ํฌ๋) .compareTo , compareToignoreCase (๋์๋ฌธ์ ๊ฐ๋ฆฌ์ง์๊ณ ๋น๊ต)
- ์์ด๋ ์ํ๋ฒณ์, ํ๊ธ์ ใฑใดใท์!
String data2 = "abc@naver.com";
if ( data2.compareTo("aba") < 0 ) {
System.out.println("์๋ค");
} else if ( data2.compareTo("aba") == 0 ) {
System.out.println("๊ฐ๋ค");
} else {
System.out.println("ํฌ๋ค");
}
๋ฌธ์์ด์ด ์๋ก ๊ฐ์์ง๋ง ํ์ธํ๋ ํจ์ .equals ํจ์ , equalsIgnoreCase (๋์๋ฌธ์ ๋ฌด์ํ๊ณ ํ์ธ)
System.out.println(data2.equals("abc@naver.com"));
System.out.println(data2.equalsIgnoreCase("aBc@Naver.com"));
if(data1.trim().equals(data2)) {
System.out.println("๋ก๊ทธ์ธ ์ฑ๊ณต");
} else {
System.out.println("์ด๋ฉ์ผ ์ฃผ์๊ฐ ๋ค๋ฆ
๋๋ค");
}