Question

有大小写字母的字符串和一个查找字符，使用类String方法indexOf（）来判断在该字符串中该字符出现的次数

Answer 1

public class TestIndexOf {
public static void main(String[] args) {
int i=(new TestIndexOf()).f();
System.out.println(i);
}
int f() {
char c='H';
String str="dhdisHIHkdsjfHiodfHHlkIFH";
int i=str.indexOf(c);
//System.out.println(i);调试用
if(i==-1) {
return 0;
}
int count=1;
while(true) {
i=str.indexOf(c,i+1);
if(i!=-1) {
count++;
}
else break;
}
return count;
}
}

Answer 2

String s = "suAERGHjavahahahahJavasFSDSnhahAibmsunjavajavahahajava";
String ToFind = "java";
int index = 0;
int count = 0;

while (index != -1) {
index = s.indexOf(ToFind);
if (index != -1) {
s = s.substring(index + ToFind.length());
count++;
}
}
System.out.println("一共有" + count + "个" + ToFind);

Answer 3

有现成的类库可以利用啊。。。

private void matchCount(String metaString, String regex) {
Pattern p = Pattern.compile(regex);
Matcher m = p.matcher(metaString);
int count = 0;
int pos = 0;
while (m.find(pos)) {
count++;
pos = m.start() + 1;
}
System.out.println("count = " + count);
}