Question

我有一个应用程序，它使用3个单独的类将信息传递给主活动，它将信息传递给一个数组，然后在输入第一个字母时列出状态。编码似乎都在那里，理论上应该像它应该......但是当我尝试输入一个字母时，我得到的不是显示任何状态列表：

Click here to show what happens on the emulator, weird error

我很确定我需要在状态类中的某处添加一个getName（）方法，从我在尝试解决问题时看到的，然后将其调用到主要活动中，但我正在努力到哪里或如何，但我在多类中没有过多经验，并且def不习惯getName（）方法。或者，如果有人有另外一个关于如何传递名称而不是整个州级的建议（我认为这是造成问题的原因）我很乐意听到/看到它！

代码如下：

main.xml中：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/activity_main" tools:context=".MainActivity">

    <Spinner
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/spinner"
        android:layout_below="@+id/button"
        android:layout_alignParentEnd="true"
        android:textAlignment="center" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Look for States below"
        android:id="@+id/textView"
        android:textSize="30dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Search States"
        android:id="@+id/button"
        android:onClick="buttonOnClick"
        android:layout_below="@+id/searchBox"
        android:layout_centerHorizontal="true" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/searchBox"
        android:textSize="35dp"
        android:layout_centerHorizontal="true"
        android:paddingBottom="15dp"
        android:hint="Type a Letter"
        android:layout_below="@+id/textView" />


</RelativeLayout>

City.java

public class City {
    String name;
    int population;

    public City () {
}

public City(int pop, String city_name){

     name = city_name;
     population = pop;

}

public String getName(){

    return name;

}


}

capital.java

public class Capital extends City {

    public Capital(int pop,String name){
        super(pop, name);
    }
}

state.java

public class State {

    City capital;
    String name;

    public State (String stateName, String capitalName, int pop){

        name = stateName;

        Capital cap = new Capital(pop, capitalName);
        capital = cap;
    }


    public boolean startWith(char s)   {
        return s == name.charAt(0);

    }



}

最后是我的mainactivity.java

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Adapter;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.SearchView;
import android.widget.TextView;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    Button stateLook;
    Spinner spinner;
    ArrayAdapter<CharSequence> adapter;
    EditText searchBox;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        stateLook = (Button) findViewById(R.id.button);
        searchBox = (EditText) findViewById(R.id.searchBox);

    };



    public void buttonOnClick(View v) {
        Button button = (Button) v;
        Spinner spinner = (Spinner) findViewById(R.id.spinner);

        ArrayList states = new ArrayList();
        states.add(new State("Alabama", "Montgomery", 205764));
        states.add(new State("Alaska", "Juneau", 31275));
        states.add(new State("Arizona", "Phoenix", 1445632));
        states.add(new State("Arkansas", "Little Rock", 193524));
        states.add(new State("California", "Sacramento", 466488));
        states.add(new State("Colorado", "Denver", 600158));
        states.add(new State("Connecticut", "Hartford", 124775));
        states.add(new State("Delaware", "Dover", 36047));
        states.add(new State("Florida", "Tallahassee", 181412));
        states.add(new State("Georgia", "Atlanta", 420003));
        states.add(new State("Hawaii", "Honolulu", 337256));
        states.add(new State("Idaho", "Boise", 205671));
        states.add(new State("Illinois", "Springfield", 116250));
        states.add(new State("India", "Indianapolis", 829718));
        states.add(new State("Iowa", "Des Moines", 203433));
        states.add(new State("Kansas", "Topeka", 127473));




        char s;
        s = searchBox.getText().charAt(0);
        ArrayList stateArray = new ArrayList();
        if (searchBox.getText().length() == 1) {
            for (int i = 0; i < states.size(); i++) {

                State state = (State) states.get(i);

                ///char s1 = state.charAt(0);

                if (state.startWith(s)) {
                    stateArray.add(state);
                }
            }
        }




       ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_spinner_item, stateArray);
       adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);




    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        TextView myText = (TextView) view;
        Toast.makeText(this, "You Selected "+ myText.getText(), Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }
}

Answer 1

您看到的错误来自<div><pre>This is a save file for LevelUp. 07 10 20 31 41 59 26 53 54 97</pre><div> <span></span>方法。在您的类中重写此项以生成所需的输出。

或更改

toString

在面向对象的类中添加getName（）方法的位置

1 个答案: