Java StringBuffer ensureCapacity()用法及代碼示例

StringBuffer類的ensureCapacity()方法可確保容量至少等於指定的minimumCapacity。

如果當前容量為StringBuffer
如果minimumCapacity參數>舊容量的兩倍加2，則新容量等於minimumCapacity，否則新容量等於舊容量的兩倍加2。
如果minimumCapacity參數作為參數傳遞

用法:

public void ensureCapacity(int minimumCapacity)

參數：此方法采用一個參數minimumCapacity，它是最小所需容量。

返回值：此方法返回不返回任何內容。

下麵的程序演示StringBuffer類的ensureCapacity()方法

示例1:

// Java program to demonstrate 
// the ensureCapacity() Method. 
  
class GFG { 
    public static void main(String[] args) 
    { 
  
        // create a StringBuffer object 
        StringBuffer str = new StringBuffer(); 
  
        // print string capacity 
        System.out.println("Before ensureCapacity "
                           + "method capacity = "
                           + str.capacity()); 
  
        // apply ensureCapacity() 
        str.ensureCapacity(18); 
  
        // print string capacity 
        System.out.println("After ensureCapacity"
                           + " method capacity = "
                           + str.capacity()); 
    } 
}

輸出：

Before ensureCapacity method capacity = 16
After ensureCapacity method capacity = 34

示例2:

// Java program to demonstrate 
// the ensureCapacity() Method. 
  
class GFG { 
    public static void main(String[] args) 
    { 
  
        // create a StringBuffer object 
        StringBuffer 
            str 
            = new StringBuffer("Geeks For Geeks"); 
  
        // print string capacity 
        System.out.println("Before ensureCapacity "
                           + "method capacity = "
                           + str.capacity()); 
  
        // apply ensureCapacity() 
        str.ensureCapacity(42); 
  
        // print string capacity 
        System.out.println("After ensureCapacity"
                           + " method capacity = "
                           + str.capacity()); 
    } 
}

輸出：

Before ensureCapacity method capacity = 31
After ensureCapacity method capacity = 64

參考文獻：
https://docs.oracle.com/javase/10/docs/api/java/lang/StringBuffer.html#ensureCapacity(int)

相關用法

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