1, StringBuffer add functionality
-
public StringBuffer append(String str):
-
Any type of data can be added to the string inside the buffer, and returns the string buffer itself
-
-
public StringBuffer insert(int offset,String str):
-
In the specified position to insert any type of data string buffer inside, and returns the string buffer itself
-
public class Demo2_StringBuffer {
/**
* * A:StringBuffer的添加功能
* public StringBuffer append(String str):
* 可以把任意类型数据添加到字符串缓冲区里面,并返回字符串缓冲区本身
* public StringBuffer insert(int offset,String str):
* 在指定位置把任意类型的数据插入到字符串缓冲区里面,并返回字符串缓冲区本身
StringBuffer是字符串缓冲区,当new的时候是在堆内存创建了一个对象,底层是一个长度为16的字符数组
当调用添加的方法时,不会再重新创建对象,在不断向原缓冲区添加字符
*/
public static void main(String[] args) {
//demo1();
StringBuffer sb = new StringBuffer("1234");
sb.insert(3, "heima"); //在指定位置添加元素,如果没有指定位置的索引就会报索引越界异常
System.out.println(sb);
}
private static void demo1() {
StringBuffer sb = new StringBuffer();
StringBuffer sb2 = sb.append(true);
StringBuffer sb3 = sb.append("heima");
StringBuffer sb4 = sb.append(100);
System.out.println(sb.toString()); //StringBuffer类中重写了toString方法,显示的是对象中的属性值
System.out.println(sb2.toString());
System.out.println(sb3.toString());
System.out.println(sb4.toString());
}
}
结果。trueheima100