当我点击操作栏项目时，我会打开一个Webview。 所以我有积分和帮助，当我点击它关闭应用程序。现在，我希望它不要关闭应用程序，但要回到主屏幕（就像应用程序启动） 这是我的主要活动
package com.CPTeam.VselCalc;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import com.actionbarsherlock.app.ActionBar;
import com.actionbarsherlock.app.SherlockActivity;
import com.actionbarsherlock.view.Menu;
import com.actionbarsherlock.view.MenuInflater;
import com.actionbarsherlock.view.MenuItem;
import crakeron.vsel.calctest.R;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.webkit.WebView;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;
public class VselcalculatortestActivity extends SherlockActivity {
private EditText freqbox1;
private EditText freqbox2;
private EditText freqbox3;
private EditText freqbox4;
private EditText freqbox5;
private EditText voltbox1;
private EditText voltbox2;
private EditText voltbox3;
private EditText voltbox4;
private EditText voltbox5;
private Spinner spinner;
public int freq1;
public int freq2;
public int freq3;
public int freq4;
public int freq5;
public int volt1;
public int volt2;
public int volt3;
public int volt4;
public int volt5;
public boolean stop=false;
public boolean freq4ornot=false;
public boolean freq5ornot=false;
//public String path;
/** Called when the activity is first created. */
private AutoUpdateApk aua;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
aua = new AutoUpdateApk(getApplicationContext());
ActionBar actionBar = getSupportActionBar();
//could be used to modify actionbar if needed
ChangeLog cl = new ChangeLog(this);
if (cl.firstRun())
cl.getLogDialog().show();
//cl.getFullLogDialog().show(); for testing
freqbox1 = (EditText) findViewById(R.id.freq1);
freqbox2 = (EditText) findViewById(R.id.freq2);
freqbox3 = (EditText) findViewById(R.id.freq3);
freqbox4 = (EditText) findViewById(R.id.freq4);
freqbox5 = (EditText) findViewById(R.id.freq5);
voltbox1 = (EditText) findViewById(R.id.volt1);
voltbox2 = (EditText) findViewById(R.id.volt2);
voltbox3 = (EditText) findViewById(R.id.volt3);
voltbox4 = (EditText) findViewById(R.id.volt4);
voltbox5 = (EditText) findViewById(R.id.volt5);
spinner = (Spinner) findViewById(R.id.spinner1);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.spinner_choices, android.R.layout.simple_spinner_item);
// Specify the layout to use when the list of choices appears
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// Apply the adapter to the spinner
spinner.setAdapter(adapter);
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener(){
public void onItemSelected(AdapterView <?> adapter, View v, int pos, long lng) {
if (pos==0){
freq4ornot=false;
freq5ornot=false;
hide_row4();
hide_row5();
}
if (pos==1){
freq4ornot=true;
freq5ornot=false;
show_row4();
hide_row5();
}
if (pos==2){
freq4ornot=true;
freq5ornot=true;
show_row4();
show_row5();
}
}
public void onNothingSelected(AdapterView <?> arg0) {
//nothing FTM
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getSupportMenuInflater();
inflater.inflate(R.menu.menu, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.Changelog:
new ChangeLog(this).getFullLogDialog().show();;
return true;
case R.id.Help:
WebView webview = new WebView(this);
setContentView(webview);
webview.loadUrl("file:///android_res/raw/help.html");
return true;
case R.id.Credits:
WebView webview1 = new WebView(this);
setContentView(webview1);
webview1.loadUrl("file:///android_res/raw/credits.html");
return true;
}
return true;
}
public void show_row4(){
freqbox4.setVisibility(View.VISIBLE);
findViewById(R.id.textView8).setVisibility(View.VISIBLE);
findViewById(R.id.TextView03).setVisibility(View.VISIBLE);
voltbox4.setVisibility(View.VISIBLE);
Log.d("VselCalc", "Showing row 4");
}
public void hide_row4(){
freqbox4.setVisibility(View.INVISIBLE);
findViewById(R.id.textView8).setVisibility(View.INVISIBLE);
findViewById(R.id.TextView03).setVisibility(View.INVISIBLE);
voltbox4.setVisibility(View.INVISIBLE);
Log.d("VselCalc", "Hiding row 4");
}
public void show_row5(){
freqbox5.setVisibility(View.VISIBLE);
findViewById(R.id.textView9).setVisibility(View.VISIBLE);
findViewById(R.id.TextView04).setVisibility(View.VISIBLE);
voltbox5.setVisibility(View.VISIBLE);
Log.d("VselCalc", "Showing row 5");
}
public void hide_row5(){
freqbox5.setVisibility(View.INVISIBLE);
findViewById(R.id.textView9).setVisibility(View.INVISIBLE);
findViewById(R.id.TextView04).setVisibility(View.INVISIBLE);
voltbox5.setVisibility(View.INVISIBLE);
Log.d("VselCalc", "Hiding row 5");
}
public void button_pressed(View button) {
voltbox1.setText("");
voltbox2.setText("");
voltbox3.setText("");
voltbox4.setText("");
voltbox5.setText("");
stop=false;
// 1. Grab values in textboxes freq1,2,3 (and 4 and 5, depending on Spinner value?) and store their values
grab_values(freq4ornot, freq5ornot);
// 2. Call calculate function with 3 (or 5) arguments
calculate(freq1, freq2, freq3, freq4, freq4ornot, freq5ornot);
// 3. call function to display each result in correct box, if stop=true, then all boxes will be displayed empty
display_volt(freq4ornot, freq5ornot);
if(stop==true) error_empty();
}
public void grab_values(boolean freq4ornot, boolean freq5ornot){
String freq1Value = freqbox1.getText().toString();//fetch what's in edittextbox and store it in a string
if(freq1Value.length()!=0){
freq1 = Integer.parseInt(freq1Value);//transform the string into an int and store it in our variable
}
if(freq1Value.length()==0){
stop=true;
freq1=0;
}
String freq2Value = freqbox2.getText().toString();
if(freq2Value.length()!=0){
freq2 = Integer.parseInt(freq2Value);//transform the string into an int and store it in our variable
}
if(freq2Value.length()==0){//check if user entered a value in box, otherwise causes crash
stop=true;
freq2=0;
}
String freq3Value = freqbox3.getText().toString();
if(freq3Value.length()!=0){
freq3 = Integer.parseInt(freq3Value);
}
if(freq3Value.length()==0){
stop=true;
freq3=0;
}
if (freq4ornot==true){
String freq4Value = freqbox4.getText().toString();
if(freq4Value.length()!=0){
freq4 = Integer.parseInt(freq4Value);
}
if(freq4Value.length()==0){
stop=true;
freq4=0;
}
if (freq5ornot==true){
String freq5Value = freqbox5.getText().toString();
if(freq5Value.length()!=0){
freq5 = Integer.parseInt(freq5Value);
}
if(freq5Value.length()==0){
stop=true;
freq5=0;
}
}}
}
public void calculate(int freq1,int freq2, int freq3, int freq4, boolean freq4ornot, boolean freq5ornot){
volt1 = formula(freq1);
volt2 = formula(freq2);
volt3 = formula(freq3);
if (freq4ornot==true){volt4 = formula(freq4);}
if (freq5ornot==true){volt5 = formula(freq5);}
}
public int formula(int freq){
int volt = ((freq/20)+2);
return volt;
}
public void display_volt (boolean freq4ornot,boolean freq5ornot){
if(stop==false){
voltbox1.setText(String.valueOf(volt1));
voltbox2.setText(String.valueOf(volt2));
voltbox3.setText(String.valueOf(volt3));
if(freq4ornot==true){voltbox4.setText(String.valueOf(volt4));}
if(freq5ornot==true){voltbox5.setText(String.valueOf(volt5));}
}
}
public void error_empty(){
Toast.makeText(getApplicationContext(), "Please enter a frequency in all the boxes", Toast.LENGTH_LONG).show();
/* For debug purposes
Toast.makeText(getApplicationContext(),"stop bool is " + stop, Toast.LENGTH_LONG).show();*/
}
//AUTODETECTION FUNCTIONS!!!
private int detected_freq1;
private int detected_freq2;
private int detected_freq3;
private int detected_freq4;
private int detected_freq5;
private String path;
public void auto_detect(View button){
stop=false;
freq4ornot=false;
freq5ornot=false;
//get the path string (for multiple device support) that leads to the cpu_freq file
{get_path();}
//read and process the file specified by path() and extract the frequencies
detect();
//fill the 4/5 freq boxes with the frequencies found
write_freq(detected_freq1,detected_freq2,detected_freq3,detected_freq4,detected_freq5);
if (stop==true){error_device();}
}
private void get_path(){
//find path for frequencies available
// for Defy (and milestone, and many other android devices) it is /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
// for multiple devices support, probably store the paths in a table in the future
path="/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies";
//for testing, put a file called "Test" in the root directory of your phone to test behavior on 4/5 freqs
//path="/Test";
}
private void detect(){
String[] segs;
FileReader fstream;
long Read;
try {fstream = new FileReader(path);
Log.d("VselCalc_AutoD", "Opened '" + path + "' file correctly");
}
catch (FileNotFoundException e) {
Toast.makeText(getApplicationContext(), "Could not read " + path, Toast.LENGTH_LONG).show();
stop=true;
return;
}
BufferedReader in = new BufferedReader(fstream, 500);
String line;
try {
while ((line = in.readLine()) != null) {
Log.d("VselCalc_AutoD", "line read:"+ line);
segs = line.trim().split(" ");
Log.d("VselCalc_AutoD", "segs length: " + segs.length);
Read = Long.parseLong(segs[0]);
Log.d("VselCalc_AutoD", "Auto-Detect freq. Read1: " + Read);
detected_freq1= (int) Read/1000;
Read = Long.parseLong(segs[1]);
Log.d("VselCalc_AutoD", "Auto-Detect freq. Read2: " + Read);
detected_freq2= (int) Read/1000;
Read = Long.parseLong(segs[2]);
Log.d("VselCalc_AutoD", "Auto-Detect freq. Read3: " + Read);
detected_freq3= (int) Read/1000;
hide_row4();
hide_row5();
spinner.setSelection(0);
if(segs.length>=4){
Read = Long.parseLong(segs[3]);
Log.d("VselCalc_AutoD", "Freq4 exists. Auto-Detect freq. Read4: " + Read);
detected_freq4= (int) Read/1000;
freq4ornot=true;
spinner.setSelection(1);
Log.d("VselCalc_AutoD", "freq4ornot changed to true after auto-detect");
Log.d("VselCalc_AutoD", "freq5 or not: " + freq5ornot);
show_row4();
hide_row5();
}
if(segs.length>=5){
Read = Long.parseLong(segs[4]);
Log.d("VselCalc_AutoD", "Freq5 exists. Auto-Detect freq. Read5: " + Read);
detected_freq5= (int) Read/1000;
freq5ornot=true;
spinner.setSelection(2);
Log.d("VselCalc_AutoD", "freq5ornot changed to true after auto-detect");
show_row4();
show_row5();
}
}
} catch (IOException e) {
Log.e("readfile", e.toString());
}
return ;
}
public void write_freq(int fr1, int fr2, int fr3, int fr4, int fr5 ){
if(stop==false){
freqbox1.setText(String.valueOf(fr1));
freqbox2.setText(String.valueOf(fr2));
freqbox3.setText(String.valueOf(fr3));
if(freq4ornot==true){freqbox4.setText(String.valueOf(fr4));}
if(freq5ornot==true){freqbox5.setText(String.valueOf(fr5));}
Toast.makeText(getApplicationContext(), "Auto-Detection successful!", Toast.LENGTH_LONG).show();
}
}
public void error_device(){
Toast.makeText(getApplicationContext(), "Function may not be supported on your device. Please contact the developers", Toast.LENGTH_LONG).show();
}
}
我没有将webview添加到layout / main.xml，因为当我点击所需的操作栏项时它会打开。
case R.id.Help:
WebView webview = new WebView(this);
setContentView(webview);
webview.loadUrl("file:///android_res/raw/help.html");
return true;
目标Android版本为4.1
答案 0 :(得分：1)
您应该覆盖活动类中的onBackPressed()。
public void onBackPressed ()
自：API级别5当活动检测到用户时调用 按下后退键。默认实现只是完成了 当前活动，但您可以覆盖它以执行任何操作。
在您的活动中复制此代码，并在其中执行任何操作。
@Override
public void onBackPressed() {
// TODO Auto-generated method stub
//this is where you start your activity
}
答案 1 :(得分：1)
当按下后退按钮时，当前意图/活动将关闭并返回到堆栈中的先前意图/活动。您在此处创建了一个webview，并将其设置为当前活动的内容。因此，当您按下该按钮时，活动将关闭，从而关闭应用程序，因为您没有任何先前的意图/活动。而是覆盖onBackPressed并在setContentView中作为主要布局。
@Override
public void onBackPressed() {
// TODO Auto-generated method stub
setContentView(R.layout.main);
//Do other functions you want to do here
}