java - "setView must have been called"- 自定义类扩展按钮

Question

所以我有一个 12 x 9 的“按钮”网格，称为“图 block ”。Tile.java 扩展了小部件“按钮”。

不过，我现在遇到了一个问题，我正在尝试让按钮显示一个 toast，它可以记忆起按下的按钮的 ID。

网格是动态添加的，我希望它保持这种状态。

这是来自 GameBoardActivity.java 的代码:

这会生成 12x9 的“方 block ”网格并为每个方 block 添加一个监听器。

    public void gridRowButtons(int iterations){
    final Tile[] gridSpaces = new Tile[12];
    LinearLayout.LayoutParams buttonParams = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT, 1.0f);
    for (int i = 0; i < 12; i++) {
        String idString = String.valueOf(aToI[iterations]) + String.valueOf(i + 1);
        final int id = getResources().getIdentifier(idString, "id", getPackageName());
        gridSpaces[i] = new Tile(getApplicationContext());
        gridSpaces[i].setText("");
        gridSpaces[i].setHeight(40);
        gridSpaces[i].setWidth(40);
        gridSpaces[i].setLayoutParams(buttonParams);
        gridSpaces[i].setId(id);
        OnClickListener showID = new OnClickListener(){
            public void onClick(View view){                 
                TextView text = (TextView) findViewById(R.id.tileIDText);
                String tileID = getApplicationContext().getResources().getResourceEntryName(id);
                text.setText(tileID);
                Tile clickedTile = (Tile) findViewById(id);
                clickedTile.tileClick(0, tileID);
            }
        };
        gridSpaces[i].setOnClickListener(showID);
    }
    LinearLayout buttonRow = new LinearLayout(getApplicationContext());
    buttonRow.setOrientation(LinearLayout.HORIZONTAL);
    buttonRow.setLayoutParams(buttonParams);
    LinearLayout boardSpace = (LinearLayout) this.findViewById(R.id.boardLayout);
    for (int i = 0; i < gridSpaces.length; i++) {
        buttonRow.addView(gridSpaces[i]);
    }
    boardSpace.addView(buttonRow);
}

这里是上面提到的 tileClick 方法:

    public void tileClick(int action, String tileID) {
    switch(action) {
        case 1 :
            //action 1
        case 2 :
            //action 2
        default :
            Context context = getContext();
            Toast toast = new Toast(context);
            Toast.makeText(context, tileID, Toast.LENGTH_SHORT);
            toast.show();
    }
}

LogCat 显示以下内容:

02-22 20:45:14.623: E/AndroidRuntime(7868): FATAL EXCEPTION: main
02-22 20:45:14.623: E/AndroidRuntime(7868): java.lang.RuntimeException: setView must have been called
02-22 20:45:14.623: E/AndroidRuntime(7868):     at android.widget.Toast.show(Toast.java:103)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at com.jneal.ecquire.Tile.tileClick(Tile.java:51)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at com.jneal.ecquire.GameBoardActivity$1.onClick(GameBoardActivity.java:55)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at android.view.View.performClick(View.java:3627)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at android.view.View$PerformClick.run(View.java:14329)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at android.os.Handler.handleCallback(Handler.java:605)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at android.os.Handler.dispatchMessage(Handler.java:92)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at android.os.Looper.loop(Looper.java:137)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at android.app.ActivityThread.main(ActivityThread.java:4511)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at java.lang.reflect.Method.invokeNative(Native Method)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at java.lang.reflect.Method.invoke(Method.java:511)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:976)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:743)
02-22 20:45:14.623: E/AndroidRuntime(7868):     at dalvik.system.NativeStart.main(Native Method)

这是怎么回事？我在我的 MainActivity.java 中获得了几乎完全相同的用于显示 toast 的代码，并且可以毫无问题地执行。是因为我扩展了 Button 并且它不知道 View 已经是什么了吗？此外，Eclipse 出于某种原因不允许我添加 setView() 。我确定我这里有封装问题，但我对它们是什么感到困惑。提前感谢您的帮助。杰拉德

Answer 1

将下面的代码行更改为以下代码行:

        Toast toast = new Toast(context);
        Toast.makeText(context, tileID, Toast.LENGTH_SHORT);
        toast.show();

更改为:

    Toast toast = Toast.makeText(context, tileID, Toast.LENGTH_SHORT);
    toast.show();       

从源码可以看出，只有当mNextView为null时才会抛出该异常。函数“makeText”应该设置它，它确实设置了它，但是您的原始代码没有捕获对它构建的 Toast 的引用。相反，您的原始代码创建了两个 Toast，并尝试“显示”尚未设置其 View 的那个。

public void show() {
    if (mNextView == null) {
        throw new RuntimeException("setView must have been called");
    }

....

public static Toast makeText(Context context, CharSequence text, int duration) {
    Toast result = new Toast(context);

    LayoutInflater inflate = (LayoutInflater)
            context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View v = inflate.inflate(com.android.internal.R.layout.transient_notification, null);
    TextView tv = (TextView)v.findViewById(com.android.internal.R.id.message);
    tv.setText(text);

    result.mNextView = v;
    result.mDuration = duration;

    return result;
}