TextChanged侦听器

Question

我仍然是Android开发的新手，我想要做的是创建一个监听器，它将包含两个TextView对象，这些对象包含区域和周边。宽度和高度是EditText对象。输入宽度和高度后，应根据calcArea和calcPerimeter方法实时显示周长和面积的值。用于侦听器的代码是基于我在这里找到的一个示例编写的。我的代码：

    package com.jtryon.rectanglecalc;

    import android.support.v7.app.ActionBarActivity;
    import android.support.v7.app.ActionBar;
    import android.support.v4.app.Fragment;
    import android.text.Editable;
    import android.text.TextWatcher;
    import android.os.Bundle;
    import android.view.LayoutInflater;
    import android.view.Menu;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.EditText;
    import android.widget.TextView;
    import android.os.Build;

    public class MainActivity extends ActionBarActivity {

        // fields in the class
        // variables that are global to this file   
        double width;
        double height;
        double area;
        double perimeter;

        // "handles" to the objects from the XML
        EditText widthEdit;
        EditText heightEdit;
        TextView areaText;
        TextView perimText;

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

            // set up handles
            widthEdit = (EditText)findViewById(R.id.width_edit);
            heightEdit = (EditText)findViewById(R.id.height_edit);
            areaText = (TextView)findViewById(R.id.area_value);
            perimText = (TextView)findViewById(R.id.perim_value);

            widthEdit.addTextChangedListener(
                    new TextWatcher() {

                        @Override
                        public void afterTextChanged(Editable arg0) {
                            // TODO Auto-generated method stub

                            // read the width out of widthEdit
                            String widthString = widthEdit.getText().toString();

                            // convert the String into a double
                            if (widthString.length() > 0) {
                                width = Double.parseDouble(widthString);
                            }

                            // read the height out of heightEdit
                            String heightString = heightEdit.getText().toString();

                            if (heightString.length() > 0) {
                                height = Double.parseDouble(heightString);
                            }


                            // calculate area
                            double area = calcArea();

                        // calculate perimeter
                        double perim = calcPerim();

                        // set the label for areaText
                        areaText.setText(Double.toString(area));

                        // set the label for perimText  
                        perimText.setText(Double.toString(perim));

                    }

                    @Override
                    public void beforeTextChanged(CharSequence s, int start,
                            int count, int after) {
                        // TODO Auto-generated method stub

                    }

                    @Override
                    public void onTextChanged(CharSequence s, int start,
                            int before, int count) {
                        // TODO Auto-generated method stub

                    }
                }
        );
    }

    double calcArea() 
    {
        return width * height;
    }

    double calcPerim()
    {
        return 2 * width * height;
    }
}

​

​

Answer 1

在onCreate中的编辑文本中定义了这一点。

  youredittext.addTextChangedListener(new TextWatcher()
    {
        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count)
        {

        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int aft )                                                                          
        {

        }

        @Override
        public void afterTextChanged(Editable s)
        {

            //call your function here of calculation here 
             yourfunctioname();

        }
    });

Answer 2

试试这个密码-

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="width" />

    <EditText
        android:id="@+id/edit_width"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="0" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="height" />

    <EditText
        android:id="@+id/edit_height"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="0" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="area" />

    <TextView
        android:id="@+id/edit_area"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="0" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="perimeter" />

    <TextView
        android:id="@+id/edit_perimeter"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="0" />

</LinearLayout>

MainActivity.java -

public class MainActivity extends ActionBarActivity {

    EditText edit_width, edit_height;
    TextView edit_area, edit_perimeter;

    double width;
    double height;
    double area;
    double perimeter;

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

        edit_area = (TextView) findViewById(R.id.edit_area);
        edit_height = (EditText) findViewById(R.id.edit_height);
        edit_width = (EditText) findViewById(R.id.edit_width);
        edit_perimeter = (TextView) findViewById(R.id.edit_perimeter);

        edit_width.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence s, int start, int before,
                    int count) {
                // TODO Auto-generated method stub

            }

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count,
                    int after) {
                // TODO Auto-generated method stub



            }

            @Override
            public void afterTextChanged(Editable s) {
                // TODO Auto-generated method stub


                String widthString = edit_width.getText().toString();

                // convert the String into a double
                if (widthString.length() > 0) {
                    width = Double.parseDouble(widthString);
                }

                // read the height out of heightEdit
                String heightString = edit_height.getText().toString();

                if (heightString.length() > 0) {
                    height = Double.parseDouble(heightString);
                }

                // calculate area
                double area = calcArea();

                // calculate perimeter
                double perim = calcPerim();

                // set the label for areaText
                edit_area.setText(Double.toString(area));

                // set the label for perimText
                edit_perimeter.setText(Double.toString(perim));

            }
        });

        edit_height.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence s, int start, int before,
                    int count) {
                // TODO Auto-generated method stub

            }

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count,
                    int after) {
                // TODO Auto-generated method stub

            }

            @Override
            public void afterTextChanged(Editable s) {
                // TODO Auto-generated method stub

                String widthString = edit_width.getText().toString();

                // convert the String into a double
                if (widthString.length() > 0) {
                    width = Double.parseDouble(widthString);
                }

                // read the height out of heightEdit
                String heightString = edit_height.getText().toString();

                if (heightString.length() > 0) {
                    height = Double.parseDouble(heightString);
                }

                // calculate area
                double area = calcArea();

                // calculate perimeter
                double perim = calcPerim();

                // set the label for areaText
                edit_area.setText(Double.toString(area));

                // set the label for perimText
                edit_perimeter.setText(Double.toString(perim));

            }
        });

    }

    double calcArea() {
        return width * height;
    }

    double calcPerim() {
        return 2 * width * height;
    }

}

希望这对你有帮助！

如果不起作用，请告诉我，我会尽力帮你更多。

Answer 3

你能澄清一下你试图在一个侦听器中用两个文本视图完成什么吗？我的第一个建议是创建一个接受文本视图作为参数的回调。然后让您的类接受由这两个类创建的两个回调。不确定这个问题。