[英]How to loop with runnable in Android
我正在做一個必須顯示圖片序列的應用程序:該序列如下:
X
必須顯示大約400毫秒; EditText
出空間。 EditText
用於獲取用戶數據。
這是我的代碼:
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);
}
}
}
當我運行此活動時,它顯示紅色X
,數組的最后一個屏幕截圖和“噪波”圖像。 Logcat顯示以下內容:
0
1
2
3
4
Screenshot
Screenshot
Screenshot
Screenshot
Screenshot
Noise
Noise
Noise
Noise
Noise
EditText
EditText
EditText
EditText
EditText
在此循環中我在做什么錯? 而且,如何在用戶放入數據之前停止循環?
更新1:
我已經按照用戶Groco的建議更改了代碼:
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,當我運行它時,應用程序顯示的是1°,3°和5°屏幕截圖(索引0、2、4),而不是全部。 我在索引上做錯了嗎?
使用用戶交互的結果重新啟動一個周期:
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;
}
嘗試這個:
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);
}
}
希望這會有所幫助
關於第二個問題,為什么用戶輸入數據后不啟動循環?
您的循環安排了一系列事件同時發生。 您可能希望在延遲計算中包括i,例如:
handler.postDelayed(new TaskScreenshot(i), i*1500 + 250);
...
更好的方法可能是為每個階段安排下一個階段。 我還注意到,您的startThread()函數實際上並未啟動新線程。 一切都發生在主線程上,這是正確的。
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