Java String 字符串

equals
字符串比较

String str = "furong";
String str1 = new String("furong");
System.out.println(str.equals(str1));

true

length

String str = "furong";
System.out.println(str.length());

6

toCharArray
转换成数组

String str = "furong";
char data[] = str.toCharArray();
for(int i = 0; i < str.length(); i++){
    System.out.print(data[i] + " ");
}
System.out.println();

f u r o n g 

charAt
取出指定位置字符

String str = "furong";
System.out.println(str.charAt(4));

n

indexOf
指定字符位置

String str = "furong@QUANGE";
System.out.println(str.indexOf('@'));

6

trim
去掉字符串前后空格

String str = "  furong@QUANGE";
System.out.println(str.indexOf('@'));

furong@QUANGE

substring
取出指定字符串

String str = "furong@QUANGE";
System.out.println(str.substring(3, 9));

ong@QU

toLowerCase
小写转换

String str = "furong@QUANGE";
System.out.println(str.toLowerCase());

furong@quange

toUpperCase
大写转换

String str = "furong@QUANGE";
System.out.println(str.toUpperCase());

FURONG@QUANGE

startsWith
判断开头字符

String str = "furong";
System.out.println(str.startsWith("f"));

true

endsWith
判断结尾字符

String str = "furong";
System.out.println(str.endsWith("g"));

true

replace
字符替换

String str = "furong@QUANGE";
System.out.println(str.replace('@', '#'));

furong#QUANGE