Java自学-数字与字符串 操纵字符串
Java常见字符串方法
示例 1 : 获取字符
charAt(int index)获取指定位置的字符
package character;
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);
}
}
示例 2 : 获取对应的字符数组
toCharArray()
获取对应的字符数组
package character;
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
System.out.println(sentence.length() == cs.length);
}
}
示例 3 : 截取子字符串
subString
截取子字符串
package character;
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";
//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);
}
}
示例 4 : 分隔
split
根据分隔符进行分隔
package character;
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";
//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);
}
}
}
示例 5 : 去掉首尾空格
trim
去掉首尾空格
package character;
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 ";
System.out.println(sentence);
//去掉首尾空格
System.out.println(sentence.trim());
}
}
示例 6 : 大小写
toLowerCase 全部变成小写
toUpperCase 全部变成大写
package character;
public class TestString {
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());
}
}
示例 7 : 定位
indexOf 判断字符或者子字符串出现的位置
contains 是否包含子字符串
package character;
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";
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"
}
}
示例 8 : 替换
replaceAll 替换所有的
replaceFirst 只替换第一个
package character;
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";
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);
}
}
练习: 间隔大写小写模式
把 lengendary 改成间隔大写小写模式,即 LeNgEnDaRy
答案:
package character;
public class TestString {
public static void main(String[] args) {
// 把 lengendary 改成间隔大写小写模式,即 LeNgEnDaRy
String s = "lengendary";
char[] cs =s.toCharArray();
int count= 0;
for (int i = 0; i < cs.length; i++) {
if(0==i%2)
cs[i] = Character.toUpperCase(cs[i]);
}
String result = new String(cs);
System.out.printf(result);
}
}
练习: 单词首字母大写
Nature has given us that two ears, two eyes, and but one tongue, to the end that we should hear and see more than we speak
把最后一个two单词首字母大写
答案:
package character;
public class TestString {
public static void main(String[] args) {
// 把最后一个two单词首字母大写
String s = "Nature has given us that two ears, two eyes, and but one tongue, to the end that we should hear and see more than we speak";
int index = s.lastIndexOf(" two ");
char[] cs = s.toCharArray();
cs[index +1] = Character.toUpperCase(cs[index+1]);
String result = new String(cs);
System.out.printf(result);
}
}
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