1，String的替换功能及案例演示
-
String replace(char old,char new)
-
String replace(String old,String new)
2，String的去除字符串两空格及案例演示
-
String trim()
3，String的按字典顺序比较两个字符串
-
int compareTo(String str)
-
int compareToIgnoreCase(String str)
public class Demo7_StringMethod {
/**
* * A:String的替换功能及案例演示
* String replace(char old,char new)
* String replace(String old,String new)
* B:String的去除字符串两空格及案例演示
* String trim()
* C:String的按字典顺序比较两个字符串及案例演示
* int compareTo(String str)(暂时不用掌握)
* int compareToIgnoreCase(String str)(了解)
*
*/
public static void main(String[] args) {
//demo1();
//demo2();
String s1 = "a";
String s2 = "aaaa";
int num = s1.compareTo(s2); //按照码表值比较
System.out.println(num);
String s3 = "黑";
String s4 = "马";
int num2 = s3.compareTo(s4);
System.out.println('黑' + 0); //查找的是unicode码表值
System.out.println('马' + 0);
System.out.println(num2);
String s5 = "heima";
String s6 = "HEIMA";
int num3 = s5.compareTo(s6);
System.out.println(num3);
int num4 = s5.compareToIgnoreCase(s6);
System.out.println(num4);
/*
* public int compare(String s1, String s2) {
int n1 = s1.length();
int n2 = s2.length();
int min = Math.min(n1, n2);
for (int i = 0; i < min; i++) {
char c1 = s1.charAt(i);
char c2 = s2.charAt(i);
if (c1 != c2) {
c1 = Character.toUpperCase(c1); //将c1字符转换成大写
c2 = Character.toUpperCase(c2); //将c2字符转换成大写
if (c1 != c2) {
c1 = Character.toLowerCase(c1); //将c1字符转换成小写
c2 = Character.toLowerCase(c2); //将c2字符转换成小写
if (c1 != c2) {
// No overflow because of numeric promotion
return c1 - c2;
}
}
}
}
return n1 - n2;
*/
}
private static void demo2() {
String s = " hei ma ";
String s2 = s.trim();
System.out.println(s2);
}
private static void demo1() {
String s = "heima";
String s2 = s.replace('i', 'o'); //用o替换i
System.out.println(s2);
String s3 = s.replace('z', 'o'); //z不存在,保留原字符不改变
System.out.println(s3);
String s4 = s.replace("ei", "ao");
System.out.println(s4);
}
}