ต้องการเช็คจำนวนรหัสไปรษณีย์ว่าให้กรอกได้แค่ 5 ตัว ต้องเขียนเช็คค่ายังไงค่ะ

 private void fn_btn_get_addr(){

        ImageButton btn1 = (ImageButton)findViewById(R.id.btnconfirm);
        btn1.setOnClickListener(new Button.OnClickListener() {
            public void onClick(View v) {


                String House_No, Alley, Road, Sub_District, District_Name, Province, Post_Code, Guidance;


                EditText txt1 = (EditText) findViewById(R.id.editadd);
                House_No = txt1.getText().toString();

                EditText txt2 = (EditText) findViewById(R.id.editalley);
                Alley = txt2.getText().toString();

                EditText txt3 = (EditText) findViewById(R.id.editroad);
                Road = txt3.getText().toString();

                EditText txt4 = (EditText) findViewById(R.id.editdis);
                Sub_District = txt4.getText().toString();

                EditText txt5 = (EditText) findViewById(R.id.editsub);
                District_Name = txt5.getText().toString();

                EditText txt6 = (EditText) findViewById(R.id.editpro);
                Province = txt6.getText().toString();

                EditText txt7 = (EditText) findViewById(R.id.editpost);
                Post_Code = txt7.getText().toString();

                EditText txt8 = (EditText) findViewById(R.id.editgui);
                Guidance = txt8.getText().toString();


                if (House_No.equals("")) {
                    msbox("Japanese Food", "กรุณากรอกเลขที่บ้าน");
                    txt1.requestFocus();
                } else if (Alley.equals("")) {
                    msbox("Japanese Food", "กรุณากรอกซอย");
                    txt2.requestFocus();
                }   else if (Road.equals("")) {
                    msbox("Japanese Food", "กรุณากรอกถนน");
                    txt3.requestFocus();
                }   else if (Sub_District.equals("")) {
                    msbox("Japanese Food", "กรุณากรอกแขวง");
                    txt4.requestFocus();
                }   else if (District_Name.equals("")) {
                    msbox("Japanese Food", "กรุณากรอกเขต");
                    txt5.requestFocus();
                }   else if (Province.equals("")) {
                    msbox("Japanese Food", "กรุณากรอกจังหวัด");
                    txt6.requestFocus();
                }   else if (Post_Code.equals("")) {
                    msbox("Japanese Food", "กรุณากรอกรหัสไปรษณีย์");
                    txt7.requestFocus();
                }   else if (Guidance.equals("")) {
                    msbox("Japanese Food", "กรุณากรอกแนะนำเส้นทาง");
                    txt8.requestFocus();
                } else {

                    selectDB(House_No, Alley, Road, Sub_District, District_Name, Province, Post_Code, Guidance, GlobalVar1.Member_ID_Ref);

                    ChangPage1();
                }