Android 监听 EditText 使 Button 是否能可用工具类

如图最近接手一个项目很多这种未输入按钮不可用的界面，所以把这种功能封装了一下

使用：

@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
public class MainActivity extends AppCompatActivity {

    private EditText editPhone,editPwd,editVerify;
    private Button btnRegister;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
    }


    private void init(){
        editPhone = (EditText) findViewById(R.id.edit_phone);
        editPwd = (EditText) findViewById(R.id.edit_pwd);
        editVerify = (EditText) findViewById(R.id.edit_verification);
        btnRegister = (Button) findViewById(R.id.btn_register);
        //setBtn对应的是按钮 addEditView可多个
        BtnToEditListenerUtils.getInstance()
                .setBtn(btnRegister)
                .addEditView(editPhone)
                .addEditView(editPwd)
                .addEditView(editVerify)
                .build();

        btnRegister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(getApplicationContext(),"Register",Toast.LENGTH_SHORT).show();
            }
        });
    }
}

BtnToEditListenerUtils

@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
public class BtnToEditListenerUtils {

    private List<EditText> editTextList = new ArrayList<>();

    private Button btn;

    public static BtnToEditListenerUtils getInstance(){
        return new BtnToEditListenerUtils();
    }

    public BtnToEditListenerUtils setBtn(Button btn){
        this.btn = btn;
        btn.setEnabled(false);
        return this;
    }

    public BtnToEditListenerUtils addEditView(EditText editText){
        editTextList.add(editText);
        return this;
    }

    public void build(){
            setWatcher();
    }

    /**
     * 给每一个EditText设置Watcher监听，当前的EditText文本不为空时遍历每一个EditText，
     * 只有都不为空时 tag为true
     */
    private void setWatcher(){

        for (int i = 0; i < editTextList.size(); i++) {
            editTextList.get(i).addTextChangedListener(new TextWatcher() {
                @Override
                public void beforeTextChanged(CharSequence s, int start, int count, int after) {

                }

                @Override
                public void onTextChanged(CharSequence s, int start, int before, int count) {

                }

                @Override
                public void afterTextChanged(Editable s) {
                    if (s.length() == 0) {
                        setBtnUnavailable();
                        return;
                    }

                    boolean tag = false;

                    for (int i = 0; i < editTextList.size(); i++) {
                        if (editTextList.get(i).getText().length() != 0) {
                            tag = true;
                        }else{
                            tag = false;
                            break;
                        }
                    }

                    if (tag) {
                        setBtnAvailable();
                    }else{
                        setBtnUnavailable();
                    }
                }
            });
        }


    }

    private void setBtnAvailable(){
        btn.setBackground(ContextCompat.getDrawable(App.getAppContext(), R.drawable.main_color_btn_round_bg));
        btn.setEnabled(true);
    }
    private void setBtnUnavailable(){
        btn.setBackground(ContextCompat.getDrawable(App.getAppContext(), R.drawable.gray_btn_round_bg));
        btn.setEnabled(true);
    }

源码
代码逻辑不难，都有注释。
end！