小编anu*_*nuj的帖子

如果用户将edittext留空,则会发生错误java.lang.NumberFormatException:Invalid int:"".错误就行了

 if (a=="" && b=="")

并且也在线

 int result = Integer.parseInt(a) + Integer.parseInt(b);
 t1.setText(Integer.toString(result));

Calci.java

package com.example.calculator;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class Calci extends Activity {
    TextView t1;
    EditText e1, e2;
    Button add, sub, mul, div;
    Context c=this;

    String b, a;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_calci);
        e1 = (EditText) findViewById(R.id.EditText01);
        e2 = (EditText) findViewById(R.id.EditText02);
        add = (Button) findViewById(R.id.add);
        sub = …

我有一个专业的微调器(下拉列表),其中我有专业列表.我想显示默认值为"选择职业".在我的xml我输入android:prompt ="选择职业"但没有任何显示.我希望"Select Profession"能够在我标记为红色的地方展示

Spinner.XML

  <Spinner
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/sp_profession"
                    android:layout_weight="1"
                    style="@style/spinner"
                    android:prompt="Select Profession"
                    android:spinnerMode="dropdown"
                    android:layout_margin="2dp"></Spinner> 

我确实做过这样的事情但是我在prompt_text上得到了null值

profession_array = getResources ().getStringArray (R.array.Profession);
        profession_str = new ArrayAdapter<String> (c, R.layout.textview_spinner, profession_array);
        prompt_text.setText ("Select Profession");
        profession_str.setDropDownViewResource (android.R.layout.simple_dropdown_item_1line);

R.layout.textview_spinner

<?xml version="1.0" encoding="utf-8"?>
<TextView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:id="@+id/prompt_text"
    android:layout_height="wrap_content"
    android:paddingBottom="10dp"
    android:paddingLeft="10dp"
    android:paddingTop="10dp"
    android:minHeight="1dp"
    android:gravity="center"
    android:textSize="20sp"
    android:textColor="@android:color/white" />

我在我的values/strings.xml中有一个专业的字符串数组.我想按字母顺序对数组进行排序.我怎样才能实现它.

strings.xml中

<string-array name="Profession">

        <item>Caretaker</item>
        <item>Cook</item>
        <item>Driver</item>
        <item>Governess</item>
        <item>HouseKeeper</item>
        <item>Maid</item>
        <item>Watchman</item>
        <item>Washerman</item>
        <item>Paper Supplier</item>
        <item>Milkman</item>
        <item>Electrician</item>
        <item>Ration Supplier</item>
        <item>Gas Supplier</item>
        <item>Volunteer</item>
        <item>Nurse</item>
        <item>Other</item>
        <item>Carpenter</item>
        <item>Plumber</item>
        <item>Mason</item>
        <item>Delivery Boy</item>
        <item>Gardner</item>
        <item>Janitor</item>
        <item>Launderer</item>
        <item>Dhobi/Press</item>
        <item>Odd Jobs</item>
        <item>Vendor</item>
        <item>Shopkeeper </item>

    </string-array>

I have this t1 as a text view. I want to store the value of t1 in a variable but i am getting "Type mismatch: cannot convert from void to Integer" error

Integer res=t1.setText(Integer.toString(result));