Foreword:
There are some defined methods in the String class that are provided for us to use. After mastering these methods, it will be very convenient in the process of string manipulation.
Get the character at the specified position: charAt (int index)
public class TestString {
public static void main(String[] args) {
String sentence = "盖伦,在进行了连续8次击杀后,获得了 超神 的称号";
char c = sentence.charAt(0);
System.out.println(c);
}
}Get the corresponding character array: toCharArray()
public class TestString {
public static void main(String[] args) {
String sentence = "盖伦,在进行了连续8次击杀后,获得了超神 的称号";
char[] cs = sentence.toCharArray(); //获取对应的字符数组
}
}Intercept string: subString()
public static void main(String[] args) {
String sentence = "盖伦,在进行了连续8次击杀后,获得了 超神 的称号";
//截取从第3个开始的字符串 （基0）
String subString1 = sentence.substring(3);
System.out.println(subString1);
//截取从第3个开始的字符串 （基0）
//到5-1的位置的字符串
//左闭右开
String subString2 = sentence.substring(3,5);
System.out.println(subString2);
}Separate the string according to the separator: split()
public static void main(String[] args) {
String sentence = "盖伦,在进行了连续8次击杀后,获得了 超神 的称号";
//根据,进行分割，得到3个子字符串
String subSentences[] = sentence.split(",");
for (String sub : subSentences) {
System.out.println(sub);
}
}Delete the spaces at the beginning and end of the string: trim()
public static void main(String[] args) {
String sentence = " 盖伦,在进行了连续8次击杀后,获得了 超神 的称号 ";
System.out.println(sentence);
//去掉首尾空格
System.out.println(sentence.trim());
}Case conversion of string: toLowerCase()/toUpperCase()
public static void main(String[] args) {
String sentence = "Garen";
//全部变成小写
System.out.println(sentence.toLowerCase());
//全部变成大写
System.out.println(sentence.toUpperCase());
}Position the characters in the string: inDexOf()
Whether to include a substring: contains()
public static void main(String[] args) {
String sentence = "盖伦,在进行了连续8次击杀后,获得了超神 的称号";
System.out.println(sentence.indexOf('8')); //字符第一次出现的位置
System.out.println(sentence.indexOf("超神")); //字符串第一次出现的位置
System.out.println(sentence.lastIndexOf("了")); //字符串最后出现的位置
System.out.println(sentence.indexOf(',',5)); //从位置5开始，出现的第一次,的位置
System.out.println(sentence.contains("击杀")); //是否包含字符串"击杀"
}Replace all: replaceAll()
replaces only the first one: replaceFist()
public static void main(String[] args) {
String sentence = "盖伦,在进行了连续8次击杀后,获得了超神 的称号";
String temp = sentence.replaceAll("击杀", "被击杀"); //替换所有的
temp = temp.replaceAll("超神", "超鬼");
System.out.println(temp);
temp = sentence.replaceFirst(",","");//只替换第一个
System.out.println(temp);
}