java中String类常用方法、属性等

package Head18;

public class java09 {

    public static void main(String[] args) {
        String s="hello,where are you from? "
                + "Are you American? do you from china?"
                + " no,I am from Australian";
        //统计空格和"re"字符串
        int n=0,n1=0;
        String s1="";
        for (int i=0;i<s.length()-2;i++){
            String r=s.substring(i, i+2);
            if (r.equals("re")){
                n++;
            }
        }
        for (int i=0;i<s.length()-1;i++){
            String r=s.substring(i, i+1);
            if (r.equals(" ")){
                n1++;
            }
        }
        //替换文本
        String s3=s;
        s3=s3.replaceAll("om", "en");
        System.out.println(s3);

        //分割字符
        String a[]=s.split("\\?");
        for (int i =0; i <a.length;i++){
            System.out.println(a[i]);
        }

        //A和a字母调换
        String s11[]=new String[s.length()];
        String s2="";
        for (int i=0;i<s.length()-1;i++){
            s11[i]=s.substring(i,i+1);
            if (s11[i].equals("A")){
                s11[i]="a";
            }else if (s11[i].equals("a")) {
                s11[i]="A";
            }
            s2=s2+s11[i];
        }

        System.out.println(s2);
        System.out.println(n);
        System.out.println(n1);

    }

}