java.lang.numberformatexception：无效的double：“”

概述得到无效Double的错误java.lang.numberformatexception无效的双倍：“”这是什么原因活动1packagecom.example.solarcalculator;importandroid.os.Bundle;importandroid.widget.Button;importandroid.annotation.SuppressLint;importa

得到无效Double的错误
java.lang.numberformatexception无效的双倍：“”
这是什么原因

活动1

package com.example.solarcalculator;        import androID.os.Bundle;        import androID.Widget.button;        import androID.annotation.Suppresslint;        import androID.app.Activity;        import androID.vIEw.Menu;        import androID.vIEw.VIEw;        import androID.vIEw.VIEw.OnClickListener;        import androID.Widget.EditText;        import androID.app.AlertDialog;        import androID.content.Intent;        @Suppresslint("UseValueOf")        public class MainActivity extends Activity {            private EditText input1;            private EditText input2;            private EditText input3;            private EditText input4;            private EditText input5;            private MainActivity mContext;    @OverrIDe    protected voID onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        mContext = this;        setContentVIEw(R.layout.activity_main);        input5 = (EditText) findVIEwByID(R.ID.input5);        button button1 = (button) findVIEwByID(R.ID.button1);        input4 = (EditText) findVIEwByID(R.ID.input4);        input1 = (EditText) findVIEwByID(R.ID.input1);        input2 = (EditText) findVIEwByID(R.ID.input2);        input3 = (EditText) findVIEwByID(R.ID.input3);        button1.setonClickListener(new OnClickListener() {            @SuppressWarnings("unused")            private AlertDialog show;            @Suppresslint("UseValueOf")            @OverrIDe            public voID onClick(VIEw arg0) {                if (  (input4.getText().toString() == " ")                         || (input4.getText().length() ==0) ||                                                (input5.getText().length() == 0)                                                 || (input5.getText().toString() == " ")){                show = new      AlertDialog.Builder(mContext).setTitle("Error")                            .setMessage("Some inputs are empty")                            .setPositivebutton("OK", null).show();                }    else if ((input1.getText().length() != 0) &&        (input3.getText().length() ==0) && (input2.getText().length() ==    0)){                     double w = new Double(input3.getText().toString());                     double t = new Double(input4.getText().toString());                     double x = new Double(input5.getText().toString());                     float e = 7;                     double num = 1000*x;                     double den = w*t*e;                     double payback = num/den;                     double money = w*t*e/1000;         Intent intent = new Intent(MainActivity.this, Power.class);                     intent.putExtra("payback", payback);                     intent.putExtra("money", money);                     startActivity(intent);                }    else if ((input1.getText().length() == 0) &&   (input3.getText().length() != 0) &&                                (input2.getText().length() != 0)){                     double t = new                                         Double(input4.getText().toString());                     double x = new Double(input5.getText().toString());                     double v = new Double(input2.getText().toString());                     double i = new Double(input3.getText().toString());                     float e = 7;                     double num = 1000*x;                     double den = v*i*t*e;                     double payback = num/den;                     double money = v*i*t*e/1000;             Intent intent = new Intent(MainActivity.this, Power.class);                     intent.putExtra("payback", payback);                     intent.putExtra("money", money);                     startActivity(intent);                }                else {                    double t = new Double(input4.getText().toString());                     double x = new Double(input5.getText().toString());                     double v = new Double(input2.getText().toString());                     double i = new Double(input3.getText().toString());                     float e = 7;                     double num = 1000*x;                     double den = v*i*t*e;                     double payback = num/den;                     double money = v*i*t*e/1000;               Intent intent = new Intent(MainActivity.this, Power.class);                     intent.putExtra("payback", payback);                     intent.putExtra("money", money);                     startActivity(intent);                }            }        });    }    @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;    }       }

活性2

package com.example.solarcalculator;    import androID.annotation.Suppresslint;    import androID.app.Activity;    import androID.os.Bundle;    import androID.Widget.TextVIEw;   @Suppresslint("NewAPI")     public class Power extends Activity {private double money;private double payback;@Suppresslint("NewAPI")@OverrIDeprotected voID onCreate(Bundle savedInstanceState) {    // Todo auto-generated method stub    super.onCreate(savedInstanceState);    setContentVIEw(R.layout.power);    payback = getIntent().getDoubleExtra("payback",0);    money = getIntent().getDoubleExtra("money", 0);    TextVIEw pay = (TextVIEw) findVIEwByID(R.ID.textVIEw2);    String payback1 = Double.toString(payback);    pay.setText(payback1);    TextVIEw mon = (TextVIEw) findVIEwByID(R.ID.textVIEw4);    String money1 = Double.toString(money);    mon.setText(money1);     }    }

我得到java.lang.numberformatexception无效的双：“”logcat中的错误
有人请帮忙

解决方法:

原因是,“”不是有效的双倍.您需要先测试String或捕获此类异常

double w;try {    w = new Double(input3.getText().toString());} catch (NumberFormatException e) {    w = 0; // your default value}

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