第二天，java之StringBuilder类

有些时候，需要由较短的字符串构建新的字符串，这时候可以用到StringBuilder类

package java20180708_1;

public class Test2018070803 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		StringBuilder stringBuilder = new StringBuilder();
		
		//向其中添加内容，append()
		//字符串
		stringBuilder.append("a");
		stringBuilder.append("b");
		stringBuilder.append("c");
		stringBuilder.append("d");
		
		//添加char类型
		stringBuilder.append('e');
		
		
		//虽然可以直接输出，但是最好用 toString()方法
		System.out.println(stringBuilder.toString());
		
		//void setCharAt(int i,char c)
		//将第i个代码单元设置为c
		stringBuilder.setCharAt(0, 'z');
		System.out.println(stringBuilder.toString());
		
		//StringBuilder insert(int offset,String str)
		//StringBuilder insert(int offset,char str)
		//在offset处插入
		stringBuilder.insert(5, "fg");
		System.out.println(stringBuilder.toString());
		
		stringBuilder.insert(7, 'h');
		System.out.println(stringBuilder.toString());
		
		
		//StringBuilder delete(int startIndex,int endIndex)
		//删除start到end-1
		stringBuilder.delete(0, 2);
		System.out.println(stringBuilder.toString());
		
		
		
	}

}

输出结果为：

abcde
zbcde
zbcdefg
zbcdefgh
cdefgh