String中常见API的使用(二)
4.去掉字符串两边的空格
package com.tedu.String;
public class TrimDeno {
public static void main(String[] args) {
String str = " a b c d ";
System.out.println("|" + str + "|");
str = str.trim();
System.out.println("|" + str + "|");
}
}
5.获取指定位置的字符
package com.tedu.String;
public class CharAtDemo {
public static void main(String[] args) {
String str1 = "this is Java";
char c = str1.charAt(5);
System.out.println(c);
String str2 = "上海自来水来自海上";
boolean b = true;
for(int i=0; i<str2.length()/2; i++) {
if(str2.charAt(i) != str2.charAt(str2.length()-i-1)) {
b=false;
break;
}
}
if(b) {
System.out.println("是回文");
} else {
System.out.println("不是回文");
}
}
}
6.判断当前字符串是否为给定的字符结尾
package com.tedu.String;
public class StartWithDemo {
public static void main(String[] args) {
String str = "this is Java";
boolean start = str.startsWith("this");
System.out.println(start);
boolean end = str.endsWith("java");
System.out.println(end);
}
}
7.将给出的字符串转换为全大写或者全小写
package com.tedu.String;
public class ToUpperCaseDemo {
public static void main(String[] args) {
String str = "你好,Wrolde!";
String upper = str.toUpperCase();
String lower = str.toLowerCase();
System.out.println(upper);
System.out.println(lower);
System.out.println(str);
}
}
8.将基本类型转换为字符串类型
package com.tedu.String;
public class ValueOfDemo {
public static void main(String[] args) {
int a = 123;
String s1 = String.valueOf(a);
System.out.println(s1);
double d = 12.456;
String s2 = String.valueOf(d);
System.out.println(s2);
String s3 = "" + (int)123;
System.out.println(s3);
}
}