String类常用功能
判断:
boolean equals(Object obj)
boolean equalsIgnoreCase(String str) //忽略大小写
boolean startsWith(String str) //是否以..开始
boolean endsWith(String str)
eg:
String s1="hello";
String s2="hello";
s1.equals(s2); //true
获取:
int length()
char charAt(int index) //索引获取字符
int indexOf(String str) //str第一次出现的索引
String substring(int start) // 从..开始截取字符串至结束
String substring(int start, int end)
转换:
char[] toCharArray()
String toLowerCase()
String toUpperCase()
eg:
String s="abcde";
char[] chs = s.toCharArray(); // chs={'a', 'b', 'c', 'd', 'e'}
去掉空格:
String trim() // 去除字符串两端的空格
字符串分割:
String[] split(String str)
StringBuilder常用功能:
字符串拼接:
StringBuilder append(任意类型)
字符串反转:
StringBuilder reverse()
类型转换:
String toString(StringBuilder sb)
StringBuilder(String s) // String转换为StringBuilder
Demo:
字符串反转:
String s="abcde";
StringBuilder sb = new StringBuilder(s);
sb.reverse();
s = sb.toString(); // s="edcba"
判断对称字符串
String s="abcba";
StringBuilder sb = new StringBuilder(s);
sb.reverse();
boolearn = s.equals(sb.toString); //true