Java基礎(2)String常用操作

1、字母大小寫轉換

String s1 = "dataPro";
String upperCase = s1.toUpperCase(); 
String lowerCase = upperCase.toLowerCase();
String s1 = "dataPro";
String subBefore = s1.substring(0, s1.indexOf("P"));
String subAfter2 = s1.substring(subBefore.length() + 1, s1.length());
String subAfter1 = s1.substring(s1.indexOf("P") + 1, s1.length());
String s1 = "  dataPro ";
String trim = s1.trim();
4、字符串轉字符數組
String s1 = "dataPro";char[] charArray = s1.toCharArray();for (char c : charArray) {     System.out.print(c);
}
5、字符串中是否包含另一字符(串)
String s1 = "dataPro";boolean re = s1.contains("ata");System.out.println(re);
6、獲取指定字符第一次/最後一次新出現的索引
String s1 = "dataPro";
int first = s1.indexOf("a"); int last = s1.lastIndexOf("a"); 
System.out.println(first); System.out.println(last); 
7、去除指定字符split (注意返回值)
String s1 = "dataPro";
String[] split = s1.split("a"); 
for (String string : split) {     System.out.println(string);   }
8、比較字符串內容是否相同
String s1 = "dataPro";String s2 = "dataPro";
boolean re = s2.equals(s1);System.out.println(re); 
9、忽略大小寫比較字符串內容是否相同（大小寫不敏感）
String s1 = "dataPro";String s2 = "dataPro";
boolean re = s2.equalsIgnoreCase(s1);System.out.println(re); 
10、判斷字符串是否以指定字符開頭/結尾
String s1 = "dataPro";
boolean re = s1.startsWith("a"); boolean re = s1.startsWith("d"); 
boolean re = s1.endsWith("o"); boolean re = s1.endsWith("P"); 
11、判斷字符串中某索引位置是否有某字符
String s1 = "dataPro";boolean re = s1.startsWith("a", 1); boolean re = s1.startsWith("d", 0); 
12、字符數組轉字符串
char[] a = {'d', 'a', 't', 'a', 'P', 'r', 'o'};
String string = new String(a);System.out.println(string); 
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