单击按钮时如何在TextView中显示ArrayList？

Question

我是Android编程的新手，过去3个月一直在观看youtube视频，试图通过反复试验来学习。我被卡住了。

我试图做的就是显示我的＆＃34; JokeList.java＆＃34;单击屏幕上的按钮后，在TextView（robotJoke）中。有人可以帮助我吗？

这是我的MainActivity.java文件

package com.example.wdoty.comedianrobot;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import java.lang.String;
import java.util.ArrayList;

public class MainActivity extends Activity{

ArrayList<String> jokeList;
TextView robotJoke;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    robotJoke = (TextView) findViewById(R.id.robotJoke);

}

public void buttonClicked(){
    printJoke();
}

public void printJoke(){
    String jokeString = jokeList.toString();
    robotJoke.setText(jokeString);
}


}

这是我的ArrayList.java（JokeList.java）

package com.example.wdoty.comedianrobot;
import java.util.*;



public class JokeList extends MainActivity{

public void jokes(){

    ArrayList<String> jokeList = new ArrayList<String>();

    jokeList.add("Why couldn't the bicycle stand up?"+
            "Because it was two tired");
    jokeList.add("What do you call a cheese that isn't yours?"+
            "Nacho Cheese!");
    jokeList.add("Before I criticize a man, I like to walk a mile in his shoes."+
            "That way, when I do criticize him, I'm a mile away and I have his shoes.");
    jokeList.add("What do you call a fish with no eye?"+
            "Fssshh");
    jokeList.add("Have you heard the one about the Corduroy pillow?"+
            "It's making HEADLINES!");
    jokeList.add("What's red and bad for your teeth?"+
            "A brick.");
    jokeList.add("Why didn't the melons get married?"+
            "Because they cantaloupe!");
    jokeList.add("What did the cobbler say when a cat wandered into his shop?"+
            "Shoe!");
    jokeList.add("What did the Buddhist say to the hot dog vendor?"+
            "Make me one with everything!");
    jokeList.add("The face of a child can say it all"+
            "especially the mouth part of the face.");
    jokeList.add("Why did the cookie go to the hospital?"+
            "Because he felt crummy.");
    jokeList.add("I intend to live forever..."+
            "So far, so good.");

}

}

这是我的activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity">

<ImageView
    android:layout_width="120dp"
    android:layout_height="120dp"
    android:id="@+id/imageView"
    android:src="@drawable/android"
    android:layout_centerHorizontal="true"/>

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/robotText"
    android:text="Hello. My name is Andy the Android I like telling jokes. Click the button below if you would like for me to tell you 1."
    android:layout_below="@+id/imageView"
    android:paddingTop="10dp" />
<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/button"
    android:layout_below="@id/robotText"
    android:paddingTop="15dp"
    android:text="Button"
    android:layout_centerHorizontal="true"
    android:onClick="buttonClicked" />
<TextView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/robotJoke"
    android:layout_below="@id/button"
    android:paddingTop="30dp"/>

</RelativeLayout>

Answer 1

您应循环遍历列表并逐个附加列表元素。

public void printJoke(){
    StringBuilder jokeStringBuilder = new StringBuilder();
    for (String s : jokeList) {
        jokeStringBuilder.append(s + "\n");
    }
    robotJoke.setText(jokeStringBuilder.toString());
}

另一个错误是您需要将buttonClicked()函数中的视图传递给buttonClicked(View v)

Answer 2

首先定义textview，而不是从ArrayList中获取所有数据并设置textview，就像这个例子一样

ready

Answer 3

您的JokeList不需要扩展MainActivity。 添加构造函数来填充数组。

public class JokeList{
private ArrayList<String> jokeList;
public JokeList(){

    jokeList = new ArrayList<String>();

    jokeList.add("Why couldn't the bicycle stand up?"+
            "Because it was two tired");
    jokeList.add("What do you call a cheese that isn't yours?"+
            "Nacho Cheese!");
    jokeList.add("Before I criticize a man, I like to walk a mile in his shoes."+
            "That way, when I do criticize him, I'm a mile away and I have his shoes.");
    jokeList.add("What do you call a fish with no eye?"+
            "Fssshh");
    jokeList.add("Have you heard the one about the Corduroy pillow?"+
            "It's making HEADLINES!");
    jokeList.add("What's red and bad for your teeth?"+
            "A brick.");
    jokeList.add("Why didn't the melons get married?"+
            "Because they cantaloupe!");
    jokeList.add("What did the cobbler say when a cat wandered into his shop?"+
            "Shoe!");
    jokeList.add("What did the Buddhist say to the hot dog vendor?"+
            "Make me one with everything!");
    jokeList.add("The face of a child can say it all"+
            "especially the mouth part of the face.");
    jokeList.add("Why did the cookie go to the hospital?"+
            "Because he felt crummy.");
    jokeList.add("I intend to live forever..."+
            "So far, so good.");

}
 public ArrayList<String> jokes(){
     return jokeList;
}


}

您的活动： 创建一个JokeList对象并向他询问ArrayList。

public class MainActivity extends Activity{

ArrayList<String> jokeList;
JokeList myJokes;
TextView robotJoke;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    robotJoke = (TextView) findViewById(R.id.robotJoke);
    myJokes = new JokeList();

}

public void buttonClicked(){
    printJoke();
}

public void printJoke(){
    jokeList = myJokes.jokes();
    String jokeString = jokeList.toString();
    robotJoke.setText(jokeString);
}


}

Answer 4

好的，我们有点不同......

package com.example.wdoty.comedianrobot;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import java.lang.String;
import java.util.ArrayList;

public class MainActivity extends Activity{

ArrayList<String> jokeList;
TextView robotJoke;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    robotJoke = (TextView) findViewById(R.id.robotJoke);
    jokeList = jokes();
}

public void buttonClicked(){
    printJoke();
}

public void printJoke(){
    Random jokeNumber = new Random();
    String jokeString = jokeList.get(jokeNumber.nextInt() % jokeList.size()).toString();
    robotJoke.setText(jokeString);
}

public ArrayList<String> jokes(){

ArrayList<String> jokeList = new ArrayList<String>();

jokeList.add("Why couldn't the bicycle stand up?"+
        "Because it was two tired");
jokeList.add("What do you call a cheese that isn't yours?"+
        "Nacho Cheese!");
jokeList.add("Before I criticize a man, I like to walk a mile in his shoes."+
        "That way, when I do criticize him, I'm a mile away and I have his shoes.");
jokeList.add("What do you call a fish with no eye?"+
        "Fssshh");
jokeList.add("Have you heard the one about the Corduroy pillow?"+
        "It's making HEADLINES!");
jokeList.add("What's red and bad for your teeth?"+
        "A brick.");
jokeList.add("Why didn't the melons get married?"+
        "Because they cantaloupe!");
jokeList.add("What did the cobbler say when a cat wandered into his shop?"+
        "Shoe!");
jokeList.add("What did the Buddhist say to the hot dog vendor?"+
        "Make me one with everything!");
jokeList.add("The face of a child can say it all"+
        "especially the mouth part of the face.");
jokeList.add("Why did the cookie go to the hospital?"+
        "Because he felt crummy.");
jokeList.add("I intend to live forever..."+
        "So far, so good.");

return jokeList;
}

}

Answer 5

public class MainActivity extends Activity{

ArrayList<String> jokeList;
TextView robotJoke;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    robotJoke = (TextView) findViewById(R.id.robotJoke);

}

public void buttonClicked(View v){ // Missing View paramter
    printJoke();
}

public void printJoke(){
//from @Ahmed Hegazy
    StringBuilder jokeStringBuilder = new StringBuilder();
    for (String s : jokeList) {
        jokeStringBuilder.append(s + "\n");
    }
    robotJoke.setText(jokeStringBuilder.toString());
}


}

Answer 6

试用此代码：

package com.example.wdoty.comedianrobot;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import java.lang.String;
import java.util.ArrayList;

public class MainActivity extends Activity{

ArrayList<String> jokeList;
TextView robotJoke;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        robotJoke = (TextView) findViewById(R.id.robotJoke);    
    }

    public void buttonClicked(View view){
        jokes();
        printJoke();
    }

    public void printJoke(){        
        String jokeString = jokeList.toString();
        robotJoke.setText(jokeString);
    }  

    public void jokes(){    
        jokeList = new ArrayList<String>();    
        jokeList.add("Why couldn't the bicycle stand up?"+
                "Because it was two tired");
        jokeList.add("What do you call a cheese that isn't yours?"+
                "Nacho Cheese!");
        jokeList.add("Before I criticize a man, I like to walk a mile in his shoes."+
                "That way, when I do criticize him, I'm a mile away and I have his shoes.");
        jokeList.add("What do you call a fish with no eye?"+
                "Fssshh");
        jokeList.add("Have you heard the one about the Corduroy pillow?"+
                "It's making HEADLINES!");
        jokeList.add("What's red and bad for your teeth?"+
                "A brick.");
        jokeList.add("Why didn't the melons get married?"+
                "Because they cantaloupe!");
        jokeList.add("What did the cobbler say when a cat wandered into his shop?"+
                "Shoe!");
        jokeList.add("What did the Buddhist say to the hot dog vendor?"+
                "Make me one with everything!");
        jokeList.add("The face of a child can say it all"+
                "especially the mouth part of the face.");
        jokeList.add("Why did the cookie go to the hospital?"+
                "Because he felt crummy.");
        jokeList.add("I intend to live forever..."+
                "So far, so good.");
        String jokeString = jokeList.toString();
        Log.d("JOKES",jokeString);    
    }