Cách sử dụng đối tượng StringBuilder

Trong post này:

  • Lấy độ dài StringBuilder
  • Convert StringBuilder to String

1. Lấy độ dài StringBuilder

public class Main {
  public static void main(String[] args) {
    StringBuilder sb = new StringBuilder(200); // Capacity:200, length:0
    sb.append("Hello"); // Capacity:200, length:5
    int len = sb.length(); // len is assigned 5
    int capacity = sb.capacity(); // capacity is assigned 200
  }
}

2. Convert to String

public class Main {
  public static void main(String[] args) {
    // Create a String object
    String s1 = new String("Hello");
    // Create a StringBuilder from of the String object s1
    StringBuilder sb = new StringBuilder(s1);

    // Append " Java" to the StringBuilder's content
    sb.append(" Java"); // Now, sb contains "Hello Java"

    // Get a String from the StringBuilder
    String s2 = sb.toString(); // s2 contains "Hello Java"

  }
}

public class Main {
  public static void main(String[] args) {
    // Length is 5
    StringBuilder sb = new StringBuilder("Hello");

    // Now the length is 7 with last two characters as null character '\u0000'
    sb.setLength(7);

    // Now the length is 2 and the content is "He"
    sb.setLength(2);

  }
}

public class Main {
  public static void main(String[] args) {
    // Create an empty StringBuffer
    StringBuilder sb = new StringBuilder();
    printDetails(sb);

    // Append "good"
    sb.append("good");
    printDetails(sb);

    // Insert "Hi " in the beginning
    sb.insert(0, "Hi ");
    printDetails(sb);

    // Delete the first o
    sb.deleteCharAt(1);
    printDetails(sb);

    // Append " be with you"
    sb.append(" be with you");
    printDetails(sb);

    // Set the length to 3
    sb.setLength(3);
    printDetails(sb);

    // Reverse the content
    sb.reverse();
    printDetails(sb);
  }

  public static void printDetails(StringBuilder sb) {
    System.out.println("Content: \"" + sb + "\"");
    System.out.println("Length: " + sb.length());
    System.out.println("Capacity: " + sb.capacity());

    // Print an empty line to separate results
    System.out.println();
  }
}

5 (100%) 1 vote
Đinh Thế Hiển
 

Mình là người thích viết lách, chia sẻ các trải nghiệm trong cuộc sống. Thích thể thao đặc biệt là thể hình. Hãy kết nối với mình nhé.

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