java - 在 TextView 中显示数组元素

Question

****我对 Java 和 android studio 非常陌生，每次单击按钮时，我都试图将数组的单个元素显示到我的 textView wordTextView 中。当我单击模拟器上的按钮时，没有显示任何内容。我也尝试使用 for 循环，但我似乎也无法让它工作。任何帮助将不胜感激****

public class MainActivity extends AppCompatActivity {

    int i = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void nextWord(View view) { //nextWord is the onclick of the button
        i = i++;
    }

    public void getNextWord(String string) {
        String [] array = {"Noun", "Adjective", "Proper Noun", "Name"};
        TextView wordTextView = findViewById(R.id.wordTextView);
        wordTextView.setText(array[i]);    
    }
}

这是 .xml 文件

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:onClick="nextWord"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/wordTextView"
        android:layout_width="155dp"
        android:layout_height="153dp"
        android:layout_marginTop="84dp"
        android:gravity="center"
        android:textSize="30sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/enterEditText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="280dp"
        android:ems="10"
        android:hint="Something"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/wordTextView" />

    <Button
        android:id="@+id/nextButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="180dp"
        android:onClick="nextWord"
        android:text="Next"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/enterEditText"
        app:layout_constraintVertical_bias="0.0" />
</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

你可以这样做:

public class MainActivity extends AppCompatActivity {

    int i = 0;

    TextView wordTextView; // declare your textView here

    // no need to create array again in "getNextWord" method
    String[] array = {"Noun", "Adjective", "Proper Noun", "Name"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); 

        // initialise text view here
        wordTextView = findViewById(R.id.wordTextView);
    }

    public void nextWord(View view) { //nextWord is the onclick of the button
        i = i++;
        getNextWord() // call this method here, without passing string
    }

    public void getNextWord() {
        // you need to check the value of "i", it should not be greater than "array" size.
        // you can simply do 
        // i = i% array.length
        // or you can check index with if-condition
        // otherwise you will get "ava.lang.ArrayIndexOutOfBoundsException" if i >= array.length
        wordTextView.setText(array[i]);    
    }
}