Java StringBuffer ensureCapacity()用法及代码示例

StringBuffer类的ensureCapacity()方法可确保容量至少等于指定的minimumCapacity。

如果当前容量为StringBuffer
如果minimumCapacity参数>旧容量的两倍加2，则新容量等于minimumCapacity，否则新容量等于旧容量的两倍加2。
如果minimumCapacity参数作为参数传递

用法:

public void ensureCapacity(int minimumCapacity)

参数：此方法采用一个参数minimumCapacity，它是最小所需容量。

返回值：此方法返回不返回任何内容。

下面的程序演示StringBuffer类的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()); 
    } 
}

输出：

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()); 
    } 
}

输出：

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

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

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注：本文由纯净天空筛选整理自AmanSingh2210大神的英文原创作品 StringBuffer ensureCapacity() method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。