[자바] 기본개념 학습하기(append, StringBuilder, StringBuffer, insert, substring)

 

append

public class Main {
    public static void main(String[] args) {
        // append
        StringBuffer sb = new StringBuffer();
        sb.append("hello");
        sb.append(" ");
        sb.append("Jump to Java");
        String result = sb.toString();
        System.out.println(result);
	}
}

 

 

 

 

**

public class Main {
    public static void main(String[] args) {
        String result = "";
        result += "hello";
        result += " ";
        result += "jump to java";
        System.out.println(result);
	}
}

 

 

 

 

---

StringBuilder, StringBuffer

public class Main {
    public static void main(String[] args) {
        // StringBuilder StringBuffer 비슷한 자료형
        StringBuilder sb = new StringBuilder();
        sb.append("hello");
        sb.append(" ");
        sb.append("jump to java");
        String result = sb.toString();
        System.out.println(result);
	}
}

 

 

 

---

insert

public class Main {
    public static void main(String[] args) {
        // insert
        StringBuffer sb = new StringBuffer();
        sb.append("jump to java");
        sb.insert(0, "hello ");
        System.out.println(sb.toString());
	}
}

 

 

 

---

substring

public class Main {
    public static void main(String[] args) {
        // substring
        StringBuffer sb = new StringBuffer();
        sb.append("Hello jump to java");
        System.out.println(sb.substring(0,4));
	}
}