[英]How to loop with runnable in Android
我正在做一个必须显示图片序列的应用程序:该序列如下:
X
必须显示大约400毫秒; EditText
出空间。 EditText
用于获取用户数据。
这是我的代码:
public class Step1Training extends Activity {
ImageFragment myImageFragment;
InputFragment myInputFragment;
Drawable cross;
ImageView myImageView;
EditText myEditText;
int i, length;
String rating;
Handler handler;
boolean continueTask;
int[] screenshots = {
R.drawable.googleplaybooks2,
R.drawable.aldiko1,
R.drawable.chaton2,
R.drawable.cinetrailer1,
R.drawable.fanpage1
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.step1_training);
handler = new Handler();
i = 0;
length = screenshots.length;
initUI();
startThread();
}
private void initUI(){
myImageFragment = (ImageFragment)getFragmentManager().findFragmentById(R.id.imageFragment);
myInputFragment = (InputFragment)getFragmentManager().findFragmentById(R.id.inputFragment);
myImageView = (ImageView)myImageFragment.getView().findViewById(R.id.screenshotImageView);
myImageView.setImageResource(R.drawable.cross300x300);
myEditText = (EditText)myInputFragment.getView().findViewById(R.id.ratingEditText);
myEditText.setVisibility(View.GONE);
}
private void startThread(){
while(i<length){
handler.postDelayed(new TaskScreenshot(i), 250);
handler.postDelayed(new TaskNoise(), 750);
handler.postDelayed(new TaskEditText(), 1000);
myEditText.setOnKeyListener(new View.OnKeyListener(){
public boolean onKey(View v, int keyCode, KeyEvent event) {
if((keyCode == KeyEvent.KEYCODE_ENTER)) {
if(myEditText.getText().toString().equals("")){
Toast.makeText(getApplicationContext(), "Inserire un numero da 1 a 9", Toast.LENGTH_SHORT).show();
return false;
} else if (Integer.parseInt(myEditText.getText().toString()) >= 1 &&
Integer.parseInt(myEditText.getText().toString()) <= 9){
return true;
}
}
return false;
}
});
System.out.println(i);
i++;
}
}
@Override
public void onBackPressed() {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Attenzione")
.setMessage("Sei sicuro/a di voler uscire dall'applicazione?\n" +
"Confermando uscirai dall'applicazione e perderai \n" +
"tutti i dati raccolti finora.")
.setCancelable(false)
.setNegativeButton("No",new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
})
.setPositiveButton("Si", new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int whichButton)
{
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
});
AlertDialog alert = builder.create();
alert.show();
}
class TaskScreenshot implements Runnable{
int j;
public TaskScreenshot(int _i){
this.j = _i;
}
@Override
public void run() {
System.out.println("Screenshot");
myEditText.setVisibility(View.GONE);
myImageFragment.getView().setVisibility(View.VISIBLE);
myImageView.setImageResource(screenshots[j]);
myImageView.getLayoutParams().width = LayoutParams.MATCH_PARENT;
myImageView.getLayoutParams().height = LayoutParams.MATCH_PARENT;
}
}
class TaskNoise implements Runnable{
@Override
public void run() {
System.out.println("Noise");
myImageView.setImageResource(R.drawable.noise);
myImageView.getLayoutParams().width = LayoutParams.MATCH_PARENT;
myImageView.getLayoutParams().height = LayoutParams.MATCH_PARENT;
}
}
class TaskEditText implements Runnable{
@Override
public void run() {
System.out.println("EditText");
myEditText.setVisibility(View.VISIBLE);
myImageFragment.getView().setVisibility(View.GONE);
}
}
}
当我运行此活动时,它显示红色X
,数组的最后一个屏幕截图和“噪波”图像。 Logcat显示以下内容:
0
1
2
3
4
Screenshot
Screenshot
Screenshot
Screenshot
Screenshot
Noise
Noise
Noise
Noise
Noise
EditText
EditText
EditText
EditText
EditText
在此循环中我在做什么错? 而且,如何在用户放入数据之前停止循环?
更新1:
我已经按照用户Groco的建议更改了代码:
private void startThread(final int i){
if(i < length){
handler.postDelayed(new TaskScreenshot(i), 250);
handler.postDelayed(new TaskNoise(), 750);
handler.postDelayed(new TaskEditText(), 1000);
myEditText.setOnKeyListener(new View.OnKeyListener(){
public boolean onKey(View v, int keyCode, KeyEvent event) {
if((keyCode == KeyEvent.KEYCODE_ENTER)) {
if(myEditText.getText().toString().equals("")){
Toast.makeText(getApplicationContext(), "Inserire un numero da 1 a 9", Toast.LENGTH_SHORT).show();
return false;
} else if (Integer.parseInt(myEditText.getText().toString()) >= 1 &&
Integer.parseInt(myEditText.getText().toString()) <= 9){
System.out.println(i);
startThread(i+1);
return true;
}
}
return false;
}
});
}
}
但是,当我运行它时,应用程序显示的是1°,3°和5°屏幕截图(索引0、2、4),而不是全部。 我在索引上做错了吗?
使用用户交互的结果重新启动一个周期:
private void startThread(int i){
if (i<length){
handler.postDelayed(new TaskScreenshot(i), 250);
handler.postDelayed(new TaskNoise(), 750);
handler.postDelayed(new TaskEditText(), 1000);
myEditText.setOnKeyListener(new View.OnKeyListener(){
public boolean onKey(View v, int keyCode, KeyEvent event) {
if((keyCode == KeyEvent.KEYCODE_ENTER)) {
if(myEditText.getText().toString().equals("")){
Toast.makeText(getApplicationContext(), "Inserire un numero da 1 a 9", Toast.LENGTH_SHORT).show();
return false;
} else if (Integer.parseInt(myEditText.getText().toString()) >= 1 &&
Integer.parseInt(myEditText.getText().toString()) <= 9){
System.out.println(i);
i++;
startThread(i);
}
}
return false;
}
});
}
return false;
}
尝试这个:
private void startThread(){
while(i<length){
handler.postDelayed(new TaskScreenshot(i), 250);
myEditText.setOnKeyListener(new View.OnKeyListener(){
....
}
}
class TaskScreenshot implements Runnable{
int j;
public TaskScreenshot(int _i){
this.j = _i;
}
@Override
public void run() {
...
handler.postDelayed(new TaskNoise(), 500);
}
}
class TaskNoise implements Runnable{
@Override
public void run() {
...
handler.postDelayed(new TaskEditText(), 250);
}
}
class TaskEditText implements Runnable{
@Override
public void run() {
...
myImageFragment.getView().setVisibility(View.GONE);
}
}
希望这会有所帮助
关于第二个问题,为什么用户输入数据后不启动循环?
您的循环安排了一系列事件同时发生。 您可能希望在延迟计算中包括i,例如:
handler.postDelayed(new TaskScreenshot(i), i*1500 + 250);
...
更好的方法可能是为每个阶段安排下一个阶段。 我还注意到,您的startThread()函数实际上并未启动新线程。 一切都发生在主线程上,这是正确的。
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