我有以下代码。就像计算器。它检查3个文本字段是否正在更改，然后返回到另一个字符串结果。除非用户删除et4字符串上的值然后应用程序崩溃，否则一切正常。这是我的代码
package com.example.b15_calc;
import com.example.b15_calc.R;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.text.Editable;
import android.text.InputType;
import android.text.TextWatcher;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnFocusChangeListener;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends Activity {
EditText et1, et2, et3, et4, et5;
Button b1, b2;
Button bt1, bt2, bt3, bt4, bt5, bt6, bt7, bt8, bt9, bt0, btdot, btbcsp, btnext;
EditText etfocused;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et1 = (EditText) findViewById(R.id.editText1);
et2 = (EditText) findViewById(R.id.editText2);
et3 = (EditText) findViewById(R.id.editText3);
et4 = (EditText) findViewById(R.id.editText4);
et5 = (EditText) findViewById(R.id.editText5);
b1 = (Button) findViewById(R.id.button1);
b2 = (Button) findViewById(R.id.button2);
bt1 = (Button) findViewById(R.id.num1);
bt2 = (Button) findViewById(R.id.num2);
bt3 = (Button) findViewById(R.id.num3);
bt4 = (Button) findViewById(R.id.num4);
bt5 = (Button) findViewById(R.id.num5);
bt6 = (Button) findViewById(R.id.num6);
bt7 = (Button) findViewById(R.id.num7);
bt8 = (Button) findViewById(R.id.num8);
bt9 = (Button) findViewById(R.id.num9);
bt0 = (Button) findViewById(R.id.num0);
btdot = (Button) findViewById(R.id.numdot);
btbcsp = (Button) findViewById(R.id.backspace);
btnext = (Button) findViewById(R.id.next);
// call of method to hide default keyboard
hideKeyboard();
et1.setInputType(InputType.TYPE_NULL);
et2.setInputType(InputType.TYPE_NULL);
et4.setInputType(InputType.TYPE_NULL);
// to check which edit text is focussed
et1.setOnFocusChangeListener(new OnFocusChangeListener() {
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus) {
// code to execute when EditText loses focus
etfocused = et1;
}
}
});
et2.setOnFocusChangeListener(new OnFocusChangeListener() {
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus) {
// code to execute when EditText loses focus
etfocused = et2;
}
}
});
et4.setOnFocusChangeListener(new OnFocusChangeListener() {
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus) {
// code to execute when EditText loses focus
etfocused = et4;
}
}
});
// coding for buttons
bt0.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("0");
}
});
bt1.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("1");
}
});
bt2.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("2");
}
});
bt3.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("3");
}
});
bt4.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("4");
}
});
bt5.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("5");
}
});
bt6.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("6");
}
});
bt7.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("7");
}
});
bt8.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("8");
}
});
bt9.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append("9");
}
});
btdot.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
etfocused.append(".");
}
});
btbcsp.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
String txt = etfocused.getText().toString();
txt = txt.length() > 1 ? txt.substring(0, txt.length() - 1) : "";
etfocused.setText(txt);
}
});
btnext.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
if (etfocused == et1) {
et2.requestFocus();
} else if (etfocused == et2) {
et4.requestFocus();
} else if (etfocused == et4) {
et1.requestFocus();
}
}
});
//step3 : write add functionality.
b2.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
finish();
startActivity(getIntent());
et1.requestFocus();
}
});
//step3 : ΜΕΤΑΒΛΗΤΕΣ
et4.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence ss, int start, int before, int count) {
// TODO Auto-generated method stub
}
@Override
public void beforeTextChanged(CharSequence ss, int start, int count, int after) {
// TODO Auto-generated method stub
}
@Override
public void afterTextChanged(Editable ss) {
// make the calculation here and set the result to et3
String f = et1.getText().toString();
double i = Double.parseDouble(f);
String s = et2.getText().toString();
double j = Double.parseDouble(s);
String w = et4.getText().toString();
double q = Double.parseDouble(w);
double price_gold = 8662.11;
double fpa = 1.23;
double fpol = 0.10;
double fpolam = 999;
double isot = 273.014;
double sint_ker = 2.6026;
double result1 = (i * price_gold) + (j * 1000) + (q * isot);
double result2 = result1 / 340.75;
int gap;
if (result2 >= fpolam) {
double result = (result2 * fpol);
double result3 = ((result2 * sint_ker) * fpa) + result;
if (result3 < 1000) {
gap = 10;
} else if (result3 < 5000) {
gap = 50;
} else //5000+
{
gap = 100;
}
int total = (int) Math.ceil(result3 / gap) * gap;
String res = String.valueOf(total);
et3.setText(res);
} else {
double result3 = ((result2 * sint_ker) * fpa);
if (result3 < 1000) {
gap = 10;
} else if (result3 < 5000) {
gap = 50;
} else //5000+
{
gap = 100;
}
int total = (int) Math.ceil(result3 / gap) * gap;
String res = String.valueOf(total);
et3.setText(res);
}
}
});
}
// to hide default keyboard
private void hideKeyboard() {
// Check if no view has focus:
View view = this.getCurrentFocus();
if (view != null) {
InputMethodManager inputManager = (InputMethodManager) this.getSystemService(Context.INPUT_METHOD_SERVICE);
inputManager.hideSoftInputFromWindow(view.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
答案 0 :(得分：2)
向我们提供准确的崩溃日志真的很不错......否则我们就可以在黑暗中拍摄。
无论如何，您很可能会在NumberFormatException行中double i = Double.parseDouble(f);点击<{1}}
尝试使用try-catch这样的解析操作：
try {
double i = Double.parseDouble(f);
......
catch (NumberFormatException e) {
// Handle error here, perhaps notify the user to input some data
}
答案 1 :(得分：0)
当您尝试解析空字符串NumberFormatException时，可能会引发''。如Veko的答案所示，您可以使用Double.parseDouble(f)附上try-catch语句，或者更恰当地说，检查字符串是否为空：
if (!TextUtils.isEmpty(f)) {
double i = Double.parseDouble(f);
}
如果字符串为空则不执行任何操作。