大家都知道Rxjava神通广大，无所不能，并有效避免Call Hell(回调地狱）模式，使大量的监听事件clickListener变换成流式编程，提高代码阅读性，提升代码维护成本。今天我通过例子详解Rxjava中的RxTextview详解，让你一举搞懂Rxjava用法，语法以及操作实例（明白 简单掌握）。

实际用户场景举例

根据用户输入的价格（价格范围0.-1)、输入的数量(10-无限）计算出总预计收入，如果写错了（举例价格范围错误、数量不对）卖出按钮无效（disable).
如果用传统的edittext.setOnChangeListner要加两个，动态计算较为难以理解。用Rxjava 则合并两个动态计算的Observable，最后动态算出结果，代码如下。

  Observable<CharSequence> priceObservable = RxTextView.textChanges(priceEdit.getEditText());
        Observable<CharSequence> countObservable = RxTextView.textChanges(countEdit.getEditText());
        sellBtnSubscription = Observable.combineLatest(priceObservable, countObservable,
                (priceSequence, countSequence) -> {
                    if (priceSequence.toString().startsWith(".")) {
                        priceSequence = "0" + priceSequence;
                        priceEdit.setText("0.");
                        priceEdit.getEditText().setSelection(priceEdit.getText().length());
                    }
                    double inputPrice = StringUtils.isEmpty(priceSequence.toString()) ? 0 : Double.parseDouble(priceSequence.toString());
                    int inputCount = StringUtils.isEmpty(countSequence.toString()) ? 0 : Integer.parseInt(countSequence.toString());
                    return inputPrice > 0 && inputCount > 0;
                }).subscribe(new Observer<Boolean>() {
            @Override
            public void onCompleted() {

            }

            @Override
            public void onError(Throwable e) {
                e.printStackTrace();
            }

            @Override
            public void onNext(Boolean isSellBtnEnable) {
                sellBtn.setEnabled(isSellBtnEnable);
                String handFeetStr = "（含手续费）";
                if (isSellBtnEnable) {
                    double predictedIncome = Double.parseDouble(priceEdit.getText().toString()) * Integer.parseInt(countEdit.getText());
                    predictedIncomeTv.setText(FormatUtil.formatMoney(predictedIncome) + "元");        //卖出联豆的预计收入（没有去除手续费的预估收入）
                    //（ 含手续费 ）
                    if (predictedIncome == 0) {
                        predictedIncomeTv.setText(FormatUtil.formatMoney(predictedIncome) + "元");        //卖出联豆的预计收入（没有去除手续费的预估收入）
                    } else {
                        predictedIncomeTv.setText(FormatUtil.formatMoney(predictedIncome) + "元" + handFeetStr);        //卖出联豆的预计收入（没有去除手续费的预估收入）
                    }
                } else {
                    predictedIncomeTv.setText(FormatUtil.formatMoney(0) + "元");        //卖出联豆的预计收入
                }
            }
        });
    }

简单详解：

获得两个EditText的 可被观察对象

获得两个edittext的可被观察的（observable<CharSequence>对象

        Observable<CharSequence> priceObservable =
RxTextView.textChanges(priceEdit.getEditText());
        Observable<CharSequence> countObservable = 
RxTextView.textChanges(countEdit.getEditText());

综合运算

动态算出 价格、数量是否合理

 sellBtnSubscription = Observable.combineLatest(priceObservable, countObservable,
                (priceSequence, countSequence) -> {
                    if (priceSequence.toString().startsWith(".")) {
                        priceSequence = "0" + priceSequence;
                        priceEdit.setText("0.");
                        priceEdit.getEditText().setSelection(priceEdit.getText().length());
                    }
                    double inputPrice = StringUtils.isEmpty(priceSequence.toString()) ? 0 : Double.parseDouble(priceSequence.toString());
                    int inputCount = StringUtils.isEmpty(countSequence.toString()) ? 0 : Integer.parseInt(countSequence.toString());
                    return inputPrice > 0 && inputCount > 0;
                }).subscribe(new Observer<Boolean>() {
            @Override
            public void onCompleted() {

            }

            @Override
            public void onError(Throwable e) {
                e.printStackTrace();
            }

            @Override
            public void onNext(Boolean isSellBtnEnable) {
                sellBtn.setEnabled(isSellBtnEnable);
                String handFeetStr = "（含手续费）";
                if (isSellBtnEnable) {
                    double predictedIncome = Double.parseDouble(priceEdit.getText().toString()) * Integer.parseInt(countEdit.getText());
                    predictedIncomeTv.setText(FormatUtil.formatMoney(predictedIncome) + "元");        //卖出XX币的预计收入（没有去除手续费的预估收入）
                    //（ 含手续费 ）
                    if (predictedIncome == 0) {
                        predictedIncomeTv.setText(FormatUtil.formatMoney(predictedIncome) + "元");        //卖出XX币的预计收入（没有去除手续费的预估收入）
                    } else {
                        predictedIncomeTv.setText(FormatUtil.formatMoney(predictedIncome) + "元" + handFeetStr);        //卖出XX币的预计收入（没有去除手续费的预估收入）
                    }
                } else {
                    predictedIncomeTv.setText(FormatUtil.formatMoney(0) + "元");        //卖出联豆的预计收入
                }
            }
        });