常用api
(1) char charAt(int index)
(2) char[] toCharArray()
(3) boolean equals(String)
(4) String substring(int start, int end)
(5) String substring(int start)
(6) boolean startsWith(String)
– 从offset位置开始, 是否以指定字符串打头
(7) boolean startsWith(String, int offset)
(8) boolean endsWith(String)
(9) int indexOf(char)
int indexOf(String)
– 从fromIndex开始往后, 第一次出现char的位置
int indexOf(char, int fromIndex)
int indexOf(String, int fromIndex)
int length()
(10)boolean equalsIgnoreCase(String)
– 去掉字符串左右两边的空白字符
(11) String trim()
public class Num6 {
public static void main(String args[]) {
String s = "www.runoob.com";
char result = s.charAt(6);
//输出结果为"n"
System.out.println(result);
}
}
import java.util.Arrays;
public class Num03 {
public static void main(String[] args) {
String s="+88 hello .com";
//1.获得某一个下标对应的字符-->charAt()
char c=s.charAt(0);
System.out.println(c);
String s1=new String();
//2.字符串不能用s==s1类比较--->equals();
boolean b=s1.equals(s);//s.equals(s1)
System.out.println("equals: "+b);
//忽略大小写比较--->equalsIgnoreCase();
boolean b1=s1.equalsIgnoreCase(s);
//3.将字符串s转换成字符数组--->toCharArray();
char[] chs=s.toCharArray();
System.out.println("toCharArray: "+ Arrays.toString(chs));
//4统计字符串的字符个数,长度--->length();
int length =s.length();
System.out.println("length: "+length);
//5.判断是否以xx开头--->startsWith();
boolean b11=s.startsWith("+88");
System.out.println("startWith: "+b11);
//6.判断是否以xx结尾---->endsWith();
boolean b2=s.endsWith(".com");
System.out.println("endsWith: "+b2);
//7.获得字符串中指定字符首次出现的位置
int index=s.indexOf('@');
System.out.println("indexOf: "+index);
//8.截取字符串,s本身没变
String sub=s.substring(0,5);
System.out.println("substring: "+sub);
//-- 去掉字符串左右两边的空白字符--->String trim()
String s3=(" sfbds ");
String s31=s3.trim();
System.out.println(s31);
}
}
输出结果如下:
+
equals: false
toCharArray: [+, 8, 8, , h, e, l, l, o, , ., c, o, m]
length: 14
startWith: true
endsWith: true
indexOf: -1
substring: +88 h
sfbds]