基于edittext字段的数学计算已更改

Question

我有3个edittext字段。 （数量，单位成本和总数）。当第一个（数量）被填充时，如果接下来输入单位成本，它会自动计算总数，或者如果输入总数，它会自动计算单位成本。个别地，功能正常。然而，当我将它们组合时，我得到了堆栈溢出错误

JAVA代码：

unit.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) {

            String qty = quantity.getText().toString();
            if (qty.matches("")) {

            } else {
                total.setEnabled(false);
                total.setFocusable(false);
                int totalcost = Integer.parseInt(qty) * Integer.parseInt(unit.getText().toString());
                total.setText(Integer.toString(totalcost));
            }

        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });

    total.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) {
            String qty = quantity.getText().toString();
            if(qty.matches("")){

            } else{
                unit.setEnabled(false);
                unit.setFocusable(false);
                int unitcost = Integer.parseInt(total.getText().toString()) / Integer.parseInt(qty) ;
                unit.setText(Integer.toString(unitcost));

            }

        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });

logcat的：

07-31 03:39:47.640    1623-1623/com.example.Prototype E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.Prototype, PID: 1623
java.lang.StackOverflowError
        at android.text.method.ReplacementTransformationMethod$ReplacementCharSequence.getChars(ReplacementTransformationMethod.java:151)
        at android.text.TextUtils.getChars(TextUtils.java:79)
        at android.text.TextUtils.indexOf(TextUtils.java:112)
        at android.text.StaticLayout.generate(StaticLayout.java:182)
        at android.text.DynamicLayout.reflow(DynamicLayout.java:284)
        at android.text.DynamicLayout.<init>(DynamicLayout.java:170)
        at android.widget.TextView.makeSingleLayout(TextView.java:6134)
        at android.widget.TextView.makeNewLayout(TextView.java:6032)
        at android.widget.TextView.checkForRelayout(TextView.java:6571)
        at android.widget.TextView.setText(TextView.java:3813)
        at android.widget.TextView.setText(TextView.java:3671)
        at android.widget.EditText.setText(EditText.java:80)
        at android.widget.TextView.setText(TextView.java:3646)
        at com.example.Prototype.productsFragmentTab$3.onTextChanged(productsFragmentTab.java:79)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.setText(TextView.java:3816)
        at android.widget.TextView.setText(TextView.java:3671)
        at android.widget.EditText.setText(EditText.java:80)
        at android.widget.TextView.setText(TextView.java:3646)
        at com.example.Prototype.productsFragmentTab$4.onTextChanged(productsFragmentTab.java:105)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.setText(TextView.java:3816)
        at android.widget.TextView.setText(TextView.java:3671)
        at android.widget.EditText.setText(EditText.java:80)
        at android.widget.TextView.setText(TextView.java:3646)
        at com.example.Prototype.productsFragmentTab$3.onTextChanged(productsFragmentTab.java:79)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.setText(TextView.java:3816)
        at android.widget.TextView.setText(TextView.java:3671)
        at android.widget.EditText.setText(EditText.java:80)
        at android.widget.TextView.setText(TextView.java:3646)
        at com.example.Prototype.productsFragmentTab$4.onTextChanged(productsFragmentTab.java:105)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.setText(TextView.java:3816)
        at android.widget.TextView.setText(TextView.java:3671)
        at android.widget.EditText.setText(EditText.java:80)
        at android.widget.TextView.setText(TextView.java:3646)
        at com.example.Prototype.productsFragmentTab$3.onTextChanged(productsFragmentTab.java:79)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.setText(TextView.java:3816)
        at android.widget.TextView.setText(TextView.java:3671)
        at android.widget.EditText.setText(EditText.java:80)
        at android.widget.TextView.setText(TextView.java:3646)
        at com.example.Prototype.productsFragmentTab$4.onTextChanged(productsFragmentTab.java:105)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.setText(TextView.java:3816)
        at android.widget.TextView.setText(TextView.java:3671)
        at android.widget.EditText.setText(EditText.java:80)
        at android.widget.TextView.setText(TextView.java:3646)
        at com.example.Prototype.productsFragmentTab$3.onTextChanged(productsFragmentTab.java:79)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.setText(TextView.java:3816)
        at android.widget.TextView.setText(TextView.java:3671)
        at android.widget.EditText.setText(EditText.java:80)
        at android.widget.TextView.setText(TextView.java:3646)
        at com.example.Prototype.productsFragmentTab$4.onTextChanged(productsFragmentTab.java:105)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.setText(TextView.java:3816)
        at android.widget.TextView.setText(TextView.java:3671)
        at android.widget.EditText.setText(EditText.java:80)
        at android.widget.TextView.setText(TextView.java:3646)
        at com.example.Prototype.productsFragmentTab$3.onTextChanged(productsFragmentTab.java:79

Answer 1

尝试使用其他变量来定义此值更改来自代码。例如：

    void yourMethod(){
        unit.addTextChangedListener(new TextWatcher() {
            boolean isChangingByCode = false;
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {


            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                if (isChangingByCode){
                    return;
                }
                String qty = quantity.getText().toString();
                if (qty.matches("")) {

                } else {
                    total.setEnabled(false);
                    total.setFocusable(false);
                    int totalcost = Integer.parseInt(qty) * Integer.parseInt(unit.getText().toString());
                    isChangingByCode = true;
                    total.setText(Integer.toString(totalcost));
                    isChangingByCode = false;
                }

            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

        total.addTextChangedListener(new TextWatcher() {
            boolean isChangingByCode = false;  
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                if (isChangingByCode){
                    return;
                }
                String qty = quantity.getText().toString();
                if(qty.matches("")){

                } else{
                    unit.setEnabled(false);
                    unit.setFocusable(false);
                    int unitcost = Integer.parseInt(total.getText().toString()) / Integer.parseInt(qty) ;
                    isChangingByCode = true;
                    unit.setText(Integer.toString(unitcost));
                    isChangingByCode = false;
                }

            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });
    }

Answer 2

设置TextView上 内TextWatcher的文字可以保证召唤无限循环。发生这种情况是因为只要更改了TextView上的文本，就会调用已注册的TextWatcher，然后再调用onTextChanged()实现文本再次设置，等等。

要解决此问题，只需在修改文本之前删除TextWatcher，然后再重新添加。这是一个例子：

@Override
public void afterTextChanged(Editable text) {

    ...

    total.removeTextChangedListener(this);
    // Modify text here
    total.addTextChangedListener(this);

    ...

}

Answer 3

尝试在int变量中保存值。

然后将其插入新的unitprice变量。

Int a =在这里获得价格;

Int b = get quntity;

Int totatl = b * a;

显示屏幕：总计

String是一个复杂的处理操作，然后你想避免在Parse操作中进行计算。将计算作为类型本身。