java - 在 android 模拟器中运行 HelloListView 时出现问题

Question

你好，我正在尝试更好地理解 android 的观点
当我尝试运行该程序时出现错误
程序将运行，但不会显示任何内容
这是HelloListView.java

package com.HelloListView;

import android.R.string;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class HelloListView extends ListActivity {
    private string[] coun;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setListAdapter (new ArrayAdapter <string>(this, R.layout.list_item,coun));

        ListView lv = getListView();
        lv.setTextFilterEnabled(true);

        lv.setOnItemClickListener (new OnItemClickListener(){
            public void onItemClick(AdapterView<?> parent, View view, int position, long id){
                Toast.makeText (getApplicationContext(), null, Toast.LENGTH_SHORT).show();

            }

        });
        @SuppressWarnings("unused")
        final String[] coun = new String[] {
            "Afghanistan", "Albania", "Algeria", "American Samoa", "Andorra",
            "Angola", "Anguilla", "Antarctica", "Antigua and Barbuda", "Argentina",
            "Armenia", "Aruba", "Australia", "Austria", "Azerbaijan",
            "Bahrain", "Bangladesh", "Barbados", "Belarus", "Belgium",
            "Belize", "Benin", "Bermuda", "Bhutan", "Bolivia",
            "Bosnia and Herzegovina", "Botswana", "Bouvet Island", "Brazil", "British Indian Ocean Territory",
            "British Virgin Islands", "Brunei", "Bulgaria", "Burkina Faso", "Burundi",
            "Cote d'Ivoire", "Cambodia", "Cameroon", "Canada", "Cape Verde",
            "Cayman Islands", "Central African Republic", "Chad", "Chile", "China",
            "Christmas Island", "Cocos (Keeling) Islands", "Colombia", "Comoros", "Congo",
            "Cook Islands", "Costa Rica", "Croatia", "Cuba", "Cyprus", "Czech Republic",
            "Democratic Republic of the Congo", "Denmark", "Djibouti", "Dominica", "Dominican Republic",
            "East Timor", "Ecuador", "Egypt", "El Salvador", "Equatorial Guinea", "Eritrea",
            "Estonia", "Ethiopia", "Faeroe Islands", "Falkland Islands", "Fiji", "Finland",
            "Former Yugoslav Republic of Macedonia", "France", "French Guiana", "French Polynesia",
            "French Southern Territories", "Gabon", "Georgia", "Germany", "Ghana", "Gibraltar",
            "Greece", "Greenland", "Grenada", "Guadeloupe", "Guam", "Guatemala", "Guinea", "Guinea-Bissau",
            "Guyana", "Haiti", "Heard Island and McDonald Islands", "Honduras", "Hong Kong", "Hungary",
            "Iceland", "India", "Indonesia", "Iran", "Iraq", "Ireland", "Israel", "Italy", "Jamaica",
            "Japan", "Jordan", "Kazakhstan", "Kenya", "Kiribati", "Kuwait", "Kyrgyzstan", "Laos",
            "Latvia", "Lebanon", "Lesotho", "Liberia", "Libya", "Liechtenstein", "Lithuania", "Luxembourg",
            "Macau", "Madagascar", "Malawi", "Malaysia", "Maldives", "Mali", "Malta", "Marshall Islands",
            "Martinique", "Mauritania", "Mauritius", "Mayotte", "Mexico", "Micronesia", "Moldova",
            "Monaco", "Mongolia", "Montserrat", "Morocco", "Mozambique", "Myanmar", "Namibia",
            "Nauru", "Nepal", "Netherlands", "Netherlands Antilles", "New Caledonia", "New Zealand",
            "Nicaragua", "Niger", "Nigeria", "Niue", "Norfolk Island", "North Korea", "Northern Marianas",
            "Norway", "Oman", "Pakistan", "Palau", "Panama", "Papua New Guinea", "Paraguay", "Peru",
            "Philippines", "Pitcairn Islands", "Poland", "Portugal", "Puerto Rico", "Qatar",
            "Reunion", "Romania", "Russia", "Rwanda", "Sqo Tome and Principe", "Saint Helena",
            "Saint Kitts and Nevis", "Saint Lucia", "Saint Pierre and Miquelon",
            "Saint Vincent and the Grenadines", "Samoa", "San Marino", "Saudi Arabia", "Senegal",
            "Seychelles", "Sierra Leone", "Singapore", "Slovakia", "Slovenia", "Solomon Islands",
            "Somalia", "South Africa", "South Georgia and the South Sandwich Islands", "South Korea",
            "Spain", "Sri Lanka", "Sudan", "Suriname", "Svalbard and Jan Mayen", "Swaziland", "Sweden",
            "Switzerland", "Syria", "Taiwan", "Tajikistan", "Tanzania", "Thailand", "The Bahamas",
            "The Gambia", "Togo", "Tokelau", "Tonga", "Trinidad and Tobago", "Tunisia", "Turkey",
            "Turkmenistan", "Turks and Caicos Islands", "Tuvalu", "Virgin Islands", "Uganda",
            "Ukraine", "United Arab Emirates", "United Kingdom",
            "United States", "United States Minor Outlying Islands", "Uruguay", "Uzbekistan",
            "Vanuatu", "Vatican City", "Venezuela", "Vietnam", "Wallis and Futuna", "Western Sahara",
            "Yemen", "Yugoslavia", "Zambia", "Zimbabwe"
          };
    }


}  

这里是list_view.xml

<?xml version="1.0" encoding="utf-8">
<TextView
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:padding="10dp"
 android:textSize="16sp">
</TextView>

感谢您的帮助，如果我需要发布其他内容，请告诉我
谢谢，
计算机科学

这是我的新 HelloListView.java

公共(public)类HelloListView扩展ListActivity { 私有(private)字符串[]计数；

public class HelloListView extends ListActivity
{
    private string[] coun = new String[] {
            "Afghanistan", "Albania", "Algeria", "American Samoa", "Andorra",
            "Angola", "Anguilla", "Antarctica", "Antigua and Barbuda", "Argentina",
            "Armenia", "Aruba", "Australia", "Austria", "Azerbaijan",
            "Bahrain", "Bangladesh", "Barbados", "Belarus", "Belgium",
            "Belize", "Benin", "Bermuda", "Bhutan", "Bolivia",
            "Bosnia and Herzegovina", "Botswana", "Bouvet Island", "Brazil", "British Indian Ocean Territory",
            "British Virgin Islands", "Brunei", "Bulgaria", "Burkina Faso", "Burundi",
            "Cote d'Ivoire", "Cambodia", "Cameroon", "Canada", "Cape Verde",
            "Cayman Islands", "Central African Republic", "Chad", "Chile", "China",
            "Christmas Island", "Cocos (Keeling) Islands", "Colombia", "Comoros", "Congo",
            "Cook Islands", "Costa Rica", "Croatia", "Cuba", "Cyprus", "Czech Republic",
            "Democratic Republic of the Congo", "Denmark", "Djibouti", "Dominica", "Dominican Republic",
            "East Timor", "Ecuador", "Egypt", "El Salvador", "Equatorial Guinea", "Eritrea",
            "Estonia", "Ethiopia", "Faeroe Islands", "Falkland Islands", "Fiji", "Finland",
            "Former Yugoslav Republic of Macedonia", "France", "French Guiana", "French Polynesia",
            "French Southern Territories", "Gabon", "Georgia", "Germany", "Ghana", "Gibraltar",
            "Greece", "Greenland", "Grenada", "Guadeloupe", "Guam", "Guatemala", "Guinea", "Guinea-Bissau",
            "Guyana", "Haiti", "Heard Island and McDonald Islands", "Honduras", "Hong Kong", "Hungary",
            "Iceland", "India", "Indonesia", "Iran", "Iraq", "Ireland", "Israel", "Italy", "Jamaica",
            "Japan", "Jordan", "Kazakhstan", "Kenya", "Kiribati", "Kuwait", "Kyrgyzstan", "Laos",
            "Latvia", "Lebanon", "Lesotho", "Liberia", "Libya", "Liechtenstein", "Lithuania", "Luxembourg",
            "Macau", "Madagascar", "Malawi", "Malaysia", "Maldives", "Mali", "Malta", "Marshall Islands",
            "Martinique", "Mauritania", "Mauritius", "Mayotte", "Mexico", "Micronesia", "Moldova",
            "Monaco", "Mongolia", "Montserrat", "Morocco", "Mozambique", "Myanmar", "Namibia",
            "Nauru", "Nepal", "Netherlands", "Netherlands Antilles", "New Caledonia", "New Zealand",
            "Nicaragua", "Niger", "Nigeria", "Niue", "Norfolk Island", "North Korea", "Northern Marianas",
            "Norway", "Oman", "Pakistan", "Palau", "Panama", "Papua New Guinea", "Paraguay", "Peru",
            "Philippines", "Pitcairn Islands", "Poland", "Portugal", "Puerto Rico", "Qatar",
            "Reunion", "Romania", "Russia", "Rwanda", "Sqo Tome and Principe", "Saint Helena",
            "Saint Kitts and Nevis", "Saint Lucia", "Saint Pierre and Miquelon",
            "Saint Vincent and the Grenadines", "Samoa", "San Marino", "Saudi Arabia", "Senegal",
            "Seychelles", "Sierra Leone", "Singapore", "Slovakia", "Slovenia", "Solomon Islands",
            "Somalia", "South Africa", "South Georgia and the South Sandwich Islands", "South Korea",
            "Spain", "Sri Lanka", "Sudan", "Suriname", "Svalbard and Jan Mayen", "Swaziland", "Sweden",
            "Switzerland", "Syria", "Taiwan", "Tajikistan", "Tanzania", "Thailand", "The Bahamas",
            "The Gambia", "Togo", "Tokelau", "Tonga", "Trinidad and Tobago", "Tunisia", "Turkey",
            "Turkmenistan", "Turks and Caicos Islands", "Tuvalu", "Virgin Islands", "Uganda",
            "Ukraine", "United Arab Emirates", "United Kingdom",
            "United States", "United States Minor Outlying Islands", "Uruguay", "Uzbekistan",
            "Vanuatu", "Vatican City", "Venezuela", "Vietnam", "Wallis and Futuna", "Western Sahara",
            "Yemen", "Yugoslavia", "Zambia", "Zimbabwe"
          };

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setListAdapter (new ArrayAdapter <string>(this, R.layout.list_item,coun));

        ListView lv = getListView();
        lv.setTextFilterEnabled(true);

        lv.setOnItemClickListener (new OnItemClickListener(){
            public void onItemClick(AdapterView<?> parent, View view, int position, long id){
                Toast.makeText (getApplicationContext(), null, Toast.LENGTH_SHORT).show();

            }

        });
    }


}

Answer 1

这是什么？

@SuppressWarnings("unused")
final String[] coun = new String[] {
    "Afghanistan", "Albania", "Algeria", "American Samoa", "Andorra",
    "Angola", "Anguilla", "Antarctica", "Antigua and Barbuda", "Argentina",
    ...

删除此数组并将所有值放入“private string[] coun;”中变量。

public class HelloListView extends ListActivity {
    private String[] coun = new String[] {
    "Afghanistan", "Albania", "Algeria", "American Samoa", "Andorra",
    "Angola", "Anguilla", "Antarctica", "Antigua and Barbuda", "Argentina",
    ...

编辑:

这是你应该做的:

package com;

import android.R.string;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class HelloListView extends ListActivity
{
    private String[] coun = new String[] {
            "Afghanistan", "Albania", "Algeria", "American Samoa", "Andorra",
            "Angola", "Anguilla", "Antarctica", "Antigua and Barbuda", "Argentina",
            "Armenia", "Aruba", "Australia", "Austria", "Azerbaijan",
            "Bahrain", "Bangladesh", "Barbados", "Belarus", "Belgium",
            "Belize", "Benin", "Bermuda", "Bhutan", "Bolivia",
            "Bosnia and Herzegovina", "Botswana", "Bouvet Island", "Brazil", "British Indian Ocean Territory",
            "British Virgin Islands", "Brunei", "Bulgaria", "Burkina Faso", "Burundi",
            "Cote d'Ivoire", "Cambodia", "Cameroon", "Canada", "Cape Verde",
            "Cayman Islands", "Central African Republic", "Chad", "Chile", "China",
            "Christmas Island", "Cocos (Keeling) Islands", "Colombia", "Comoros", "Congo",
            "Cook Islands", "Costa Rica", "Croatia", "Cuba", "Cyprus", "Czech Republic",
            "Democratic Republic of the Congo", "Denmark", "Djibouti", "Dominica", "Dominican Republic",
            "East Timor", "Ecuador", "Egypt", "El Salvador", "Equatorial Guinea", "Eritrea",
            "Estonia", "Ethiopia", "Faeroe Islands", "Falkland Islands", "Fiji", "Finland",
            "Former Yugoslav Republic of Macedonia", "France", "French Guiana", "French Polynesia",
            "French Southern Territories", "Gabon", "Georgia", "Germany", "Ghana", "Gibraltar",
            "Greece", "Greenland", "Grenada", "Guadeloupe", "Guam", "Guatemala", "Guinea", "Guinea-Bissau",
            "Guyana", "Haiti", "Heard Island and McDonald Islands", "Honduras", "Hong Kong", "Hungary",
            "Iceland", "India", "Indonesia", "Iran", "Iraq", "Ireland", "Israel", "Italy", "Jamaica",
            "Japan", "Jordan", "Kazakhstan", "Kenya", "Kiribati", "Kuwait", "Kyrgyzstan", "Laos",
            "Latvia", "Lebanon", "Lesotho", "Liberia", "Libya", "Liechtenstein", "Lithuania", "Luxembourg",
            "Macau", "Madagascar", "Malawi", "Malaysia", "Maldives", "Mali", "Malta", "Marshall Islands",
            "Martinique", "Mauritania", "Mauritius", "Mayotte", "Mexico", "Micronesia", "Moldova",
            "Monaco", "Mongolia", "Montserrat", "Morocco", "Mozambique", "Myanmar", "Namibia",
            "Nauru", "Nepal", "Netherlands", "Netherlands Antilles", "New Caledonia", "New Zealand",
            "Nicaragua", "Niger", "Nigeria", "Niue", "Norfolk Island", "North Korea", "Northern Marianas",
            "Norway", "Oman", "Pakistan", "Palau", "Panama", "Papua New Guinea", "Paraguay", "Peru",
            "Philippines", "Pitcairn Islands", "Poland", "Portugal", "Puerto Rico", "Qatar",
            "Reunion", "Romania", "Russia", "Rwanda", "Sqo Tome and Principe", "Saint Helena",
            "Saint Kitts and Nevis", "Saint Lucia", "Saint Pierre and Miquelon",
            "Saint Vincent and the Grenadines", "Samoa", "San Marino", "Saudi Arabia", "Senegal",
            "Seychelles", "Sierra Leone", "Singapore", "Slovakia", "Slovenia", "Solomon Islands",
            "Somalia", "South Africa", "South Georgia and the South Sandwich Islands", "South Korea",
            "Spain", "Sri Lanka", "Sudan", "Suriname", "Svalbard and Jan Mayen", "Swaziland", "Sweden",
            "Switzerland", "Syria", "Taiwan", "Tajikistan", "Tanzania", "Thailand", "The Bahamas",
            "The Gambia", "Togo", "Tokelau", "Tonga", "Trinidad and Tobago", "Tunisia", "Turkey",
            "Turkmenistan", "Turks and Caicos Islands", "Tuvalu", "Virgin Islands", "Uganda",
            "Ukraine", "United Arab Emirates", "United Kingdom",
            "United States", "United States Minor Outlying Islands", "Uruguay", "Uzbekistan",
            "Vanuatu", "Vatican City", "Venezuela", "Vietnam", "Wallis and Futuna", "Western Sahara",
            "Yemen", "Yugoslavia", "Zambia", "Zimbabwe"
          };

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setListAdapter (new ArrayAdapter <String>(this, R.layout.list_item,coun));

        ListView lv = getListView();
        lv.setTextFilterEnabled(true);

        lv.setOnItemClickListener (new OnItemClickListener(){
            public void onItemClick(AdapterView<?> parent, View view, int position, long id){
                Toast.makeText (getApplicationContext(), null, Toast.LENGTH_SHORT).show();

            }
        });
    }
}