Question

我正在尝试自学android并且我完全卡住了。我有一个包含9个按钮的数组，默认文本是“button”，还有一个TextView，其默认文本是“Hello World！”。

I can get the TextView's text to change to Lorem Ipsum, 
but I can't get the button array text to change to "Btn something"

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });
    rv = new RemoteViews(getPackageName(), R.layout.activity_main);
    int i = 0;
    bArr[i++] = (Button) findViewById(R.id.button1);
    bArr[i++] = (Button) findViewById(R.id.button2);
    bArr[i++] = (Button) findViewById(R.id.button3);
    bArr[i++] = (Button) findViewById(R.id.button4);
    bArr[i++] = (Button) findViewById(R.id.button5);
    bArr[i++] = (Button) findViewById(R.id.button6);
    bArr[i++] = (Button) findViewById(R.id.button7);
    bArr[i++] = (Button) findViewById(R.id.button8);
    bArr[i] = (Button) findViewById(R.id.button9);

    for(i = 0; i < 0; i++) {
        bArr[i].setText("Btn " + i); //Doesn't Work
        rv.setTextViewText(bArr[i].getId(), "Btn " + i); // Doesn't work
        bArr[i].setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Btn pressed", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }

    ((TextView)findViewById(R.id.text1)).setText("Lorem Ipsum"); // Works
}

XML文件：

<android.support.constraint.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:paddingLeft="16dp"
android:paddingRight="16dp"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="edu.csub.cs.cenri3390.MainActivity"
tools:showIn="@layout/activity_main"
tools:layout_editor_absoluteY="25dp"
tools:layout_editor_absoluteX="0dp">

<Button
    android:id="@+id/button7"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Button"
    tools:layout_constraintTop_creator="1"
    tools:layout_constraintRight_creator="1"
    app:layout_constraintRight_toRightOf="@+id/button4"
    android:layout_marginTop="11dp"
    app:layout_constraintTop_toBottomOf="@+id/button4"
    tools:layout_constraintLeft_creator="1"
    app:layout_constraintLeft_toLeftOf="@+id/button4" />
<!-- 8 more buttons.../>
<TextView
    android:id="@+id/text1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello World!"
    tools:layout_constraintRight_creator="1"
    tools:layout_constraintBottom_creator="1"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    tools:layout_constraintLeft_creator="1"
    android:layout_marginBottom="91dp"
    app:layout_constraintLeft_toLeftOf="parent" />

  </android.support.constraint.ConstraintLayout>

按钮出现故障，但这无关紧要，我希望如此。无论如何，它们被放置在正确的位置。

Answer 1

你的for循环在这里被不正确地实例化，它永远不会执行。你已设置i=0并告诉循环执行只要i<0，这当然是不正确的。

for(i = 0; i < 0; i++) {
    bArr[i].setText("Btn " + i); //Doesn't Work
    rv.setTextViewText(bArr[i].getId(), "Btn " + i); // Doesn't work
    bArr[i].setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Btn pressed", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });
}

如果您知道总有9个按钮，则可以for(i=0;i<9;i++)。

此外，只需提示，您可以使用layout.getChildCount()迭代按钮，并使用layout.getChildAt(i)分别访问它们。所以不要做

rv = new RemoteViews(getPackageName(), R.layout.activity_main);
int i = 0;
bArr[i++] = (Button) findViewById(R.id.button1);
...
bArr[i] = (Button) findViewById(R.id.button9);

你能够做到

for(i=0;i<layout.getChildCount();i++) {
    // Do something
    layout.getChildAt(i).setText('something');
}

Android新手，按钮文字不变

1 个答案: