使用java替换字符串中的字符

String str = "Hello World";
String newStr = str.replace('o', 'a');
System.out.println(newStr);  // 输出结果为 "Hella Warld"

String str = "Hello World";
StringBuilder sb = new StringBuilder(str);
for (int i = 0; i < sb.length(); i++) {
    if (sb.charAt(i) == 'o') {
        sb.setCharAt(i, 'a');
    }
}
String newStr = sb.toString();
System.out.println(newStr);  // 输出结果为 "Hella Warld"

String str = "Hello World";
String newStr = str.replaceAll("o", "a");
System.out.println(newStr);  // 输出结果为 "Hella Warld"