手机中间四位为***** 138*****580

private String fomatPhone(String phone){
			String no="";
			if(!TextUtils.isEmpty(phone)){
				for(int i=0;i<phone.length();i++){
					char c=mUserInfo.phone.charAt(i);
					if(i>2 && i<phone.length()-4){
						no+="*";
					}else{
						no+=c;
					}
				}
			}
			return no;
		}

不过我之前还想到一种，就是用分割：
private String phone="13816175809";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String str1=phone.substring(0, 2);
String str2=phone.substring(phone.length()-4,phone.length());
((Button)findViewById(R.id.btn)).setText(str1+"****"+str2);