java—从listview获取edittext值，进行double并进行计算

bvhaajcl  于 2021-07-09  发布在  Java
关注(0)|答案(2)|浏览(358)

我一直坚持我的密码。。
我已经用edittexts创建了一个arraylist，用户在其中填充，我试图从那些值（双倍值）中获取值，进行一些计算，并用textview将它们显示给另一个arraylist。
这是我第一次使用这个代码。。。

counter++;

EditText ed;
List<EditText> allEds = new ArrayList<EditText>();
TextView tv;
List<TextView> allTvs = new ArrayList<TextView>();

ed = new EditText(Main_5.this);
allEds.add(ed);
ed.setId(counter);
ed.setLayoutParams(new TableLayout.LayoutParams(0, ViewGroup.LayoutParams.WRAP_CONTENT, 0.5f));
linearLayout.addView(ed);
ed.setInputType(InputType.TYPE_CLASS_NUMBER| InputType.TYPE_NUMBER_FLAG_DECIMAL);

tv = new TextView(Main_5.this);
allTvs.add(tv);
tv.setId(counter);
tv.setLayoutParams(new TableLayout.LayoutParams(0, ViewGroup.LayoutParams.WRAP_CONTENT, 0.5f));
linearLayout.addView(tv);

直到此部件工作并在单击按钮时创建edittext和TextView。
对于检索并使字符串加倍，我有这样的想法，但它不起作用：(

Double[] doubles = new Double[allEds.size()];
String[] strings = new String[allEds.size()];

for(i=0;i<allEds.size();i++){

   strings[i] = allEds.get(i).getText().toString();
   doubles[i] = Double.parseDouble(strings[i]);
}

有人能帮我吗？？谢谢您！！

更新

更改后，如果有人能发现问题，我将发布我的代码。。
我的xml文件是：

< RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"<br/>
    xmlns:tools="http://schemas.android.com/tools" <br/>android:layout_width="match_parent"<br/>
    android:layout_height="match_parent" <br/>android:paddingLeft="@dimen/activity_horizontal_margin"<br/>
    android:paddingRight="@dimen/activity_horizontal_margin"<br/>
    android:paddingTop="@dimen/activity_vertical_margin"<br/>
    android:paddingBottom="@dimen/activity_vertical_margin" <br/>tools:context=".MainActivity"><br/>

<EditText
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:inputType="numberDecimal"
    android:ems="10"
    android:id="@+id/txtInput"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true" />

<EditText
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:inputType="numberDecimal"
    android:ems="10"
    android:id="@+id/txtInput2"
    android:layout_alignParentTop="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true" />

<EditText
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:inputType="numberDecimal"
    android:ems="10"
    android:id="@+id/txtInput3"
    android:layout_below="@+id/delete"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceMedium"
    android:id="@+id/textView"
    android:layout_alignBaseline="@+id/txtInput3"
    android:layout_alignBottom="@+id/txtInput3"
    android:layout_alignLeft="@+id/delete"
    android:layout_alignStart="@+id/delete"/>

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/txtInput3">

<LinearLayout
    android:id="@+id/linearLayout"
    android:layout_width="match_parent"
    android:orientation="vertical"
    android:layout_height="wrap_content"/>
 </ScrollView>

<Button
    android:id="@+id/add"
    android:layout_width="60dp"
    android:layout_height="60dp"
    android:text=""
    android:background="@android:drawable/ic_menu_add"
    android:tint="#91d1be"
    android:layout_marginRight="11dp"
    android:layout_marginEnd="11dp"
    android:layout_below="@+id/txtInput"
    android:layout_alignRight="@+id/txtInput3"
    android:layout_alignEnd="@+id/txtInput3"
     />

我的java文件是：

public class Main_5 extends Activity {

private LinearLayout mainLinearLayout;
int counter=0, i=0;

EditText mEditText1,mEditText2,mEditText3;
TextView mTextView;
Button add,delete;
Double calculatedValue;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_5);

    mEditText1 = (EditText)findViewById(R.id.txtInput);
    mEditText2 = (EditText)findViewById(R.id.txtInput2);
    mEditText3 = (EditText)findViewById(R.id.txtInput3);
    mTextView = (TextView)findViewById(R.id.textView);

    add = (Button) findViewById(R.id.add);
    mainLinearLayout = (LinearLayout) findViewById(R.id.linearLayout);

    add.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if ((String.valueOf(mEditText1.getText()).length() == 0) ||
                    (String.valueOf(mEditText2.getText()).length() == 0) ||
                    (String.valueOf(mEditText3.getText()).length() == 0))
                Toast.makeText(getApplicationContext(), "Fill the fields", Toast.LENGTH_LONG).show();

            else {
                Double value1 = Double.parseDouble(String.valueOf(mEditText1.getText()));
                Double value2 = Double.parseDouble(String.valueOf(mEditText2.getText()));
                Double value3 = Double.parseDouble(String.valueOf(mEditText3.getText()));

                calculatedValue = (value2 / value3);
                mTextView.setText(calculatedValue.toString());

                counter++;

                LinearLayout linearLayout = new LinearLayout(Main_5.this);
                TableLayout.LayoutParams lp = new TableLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT, 1f);
                linearLayout.setLayoutParams(lp);
                linearLayout.setOrientation(LinearLayout.HORIZONTAL);

                EditText ed;
                List<EditText> allEds = new ArrayList<EditText>();
                TextView tv;
                List<TextView> allTvs = new ArrayList<TextView>();

                ed = new EditText(Main_5.this);
                allEds.add(ed);
                ed.setId(counter);
                ed.setLayoutParams(new TableLayout.LayoutParams(0, ViewGroup.LayoutParams.WRAP_CONTENT, 0.5f));
                linearLayout.addView(ed);
                ed.setInputType(InputType.TYPE_CLASS_NUMBER| InputType.TYPE_NUMBER_FLAG_DECIMAL);

                tv = new TextView(Main_5.this);
                allTvs.add(tv);
                tv.setId(counter);
                tv.setLayoutParams(new TableLayout.LayoutParams(0, ViewGroup.LayoutParams.WRAP_CONTENT, 0.5f));
                linearLayout.addView(tv);

                mainLinearLayout.addView(linearLayout);

                Double[] doubles = new Double[allEds.size()];
                String[] strings = new String[allEds.size()];
                Double[] results = new Double[allEds.size()];
                String[] resultStrings = new String[allTvs.size()];

                for(i=0;i<allEds.size();i++){

                    strings[i] = allEds.get(i).getText().toString();
                    if(strings[i].length()>0){
                        doubles[i] = Double.parseDouble(strings[i]);

                        results[i] = (doubles[i]*value2);

                        resultStrings[i] = Double.toString(results[i]);

                       allTvs.get(i).setText(String.valueOf(results[i]));

                    }}}}});}}

（为了减少空间，我一下子关上了门；（p）
有人能帮忙吗？？我的问题是我看不到文本视图的结果。。。
谢谢您！！

JavaandroidListView

2条答案

按热度按时间
3phpmpom

3phpmpom1#

这是由于 java.lang.NumberFormatException ，这意味着要将空字符串或非数字字符串转换为 Double .
在循环中转换之前过滤字符串，如下所示：，

Double[] doubles = new Double[allEds.size()];
String[] strings = new String[allEds.size()];

for(i=0;i<allEds.size();i++){

strings[i] = allEds.get(i).getText().toString();

//Say no to NumberFormatException
if(strings[i] == null) {
     doubles[i] = 0.0; 
  } else if(strings[i].trim().length < 1){
     doubles[i] = 0.0; 
 } else {
    doubles[i] = Double.parseDouble(strings[i]);
 }

 //now set the textview text
 allTvs.get(i).setText(doubles[i] + ""); //Yeah,  + ""

/* If the textView text didn't change for some reasons (which I don't know)
   then get the textView  and set its text then replace it with the one in 
   list
   e.g:/ 
 */

 TextView tv = allTvs.get(i);
 tv.setText(doubles[i] + "");
 allTvs.add(i, tv);
}
赞(0）分享  回复(0）举报  2021-07-09
cwdobuhd

cwdobuhd2#

我有你的问题。您正在尝试将空字符串转换为双值。这就是为什么你得到numberformatexception。您的代码应该是这样的：

Double[] doubles = new Double[allEds.size()];
String[] strings = new String[allEds.size()];

for(i=0;i<allEds.size();i++){

   strings[i] = allEds.get(i).getText().toString();
   if(strings[i].length()>0){
       doubles[i] = Double.parseDouble(strings[i]);
   }
}
赞(0）分享  回复(0）举报  2021-07-09
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