Java StringBuffer ensureCapacity()方法

java.lang.StringBuffer.ensureCapacity() 方法确保了容量至少等于指定的最小值。如果当前容量小于参数，那么一个新的内部数组分配较大的容量。

1 语法

public void ensureCapacity(int minimumCapacity)

2 参数

minimumCapacity ： 这是最低所需量。

3 返回值

此方法不返回任何值。

4 示例 

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java StringBuffer ensureCapacity()方法
 */
import java.lang.*;

public class StringBufferDemo {

  public static void main(String[] args) {
  
    StringBuffer buff1 = new StringBuffer("tuts point");
    System.out.println("buffer1 = " + buff1);

    // returns the current capacity of the string buffer 1
    System.out.println("Old Capacity = " + buff1.capacity());
    /* increases the capacity, as needed, to the specified amount in the 
    given string buffer object */
    // returns twice the capacity plus 2
    buff1.ensureCapacity(28);
    System.out.println("New Capacity = " + buff1.capacity());

    StringBuffer buff2 = new StringBuffer("compile online");
    System.out.println("buffer2 = " + buff2);
    // returns the current capacity of string buffer 2
    System.out.println("Old Capacity = " + buff2.capacity());
    /* returns the old capacity as the capacity ensured is less than the
    old capacity */
    buff2.ensureCapacity(29);
    System.out.println("New Capacity = " + buff2.capacity());
  }
}

输出结果为：

buffer1 = tuts point
Old Capacity = 26
New Capacity = 54
buffer2 = compile online
Old Capacity = 30
New Capacity = 30