Java android中使用TextWaxtcher（如android中的现金计算器应用程序）计算editText值的总和

我正在尝试开发一个现金计算器应用程序克隆。因此，我现在面临一个问题，当我在editText1中输入一个值时，应用程序就会崩溃

因此，我的问题是如何使用三个编辑文本的值的文本观察者执行加法，并将最终的总计显示到最终总计文本视图。另外，我想在“T1文本视图”上同时显示EditText1的值。对于EditText2和EditText3也是如此。将值显示到T1、T2和T3后。然后获取T1文本视图、T2文本视图和T3文本视图的值，然后将其显示在最终总文本视图上

这是我迄今为止完成的代码

这是my MainActivity.java代码

package com.dinocodeacademy.cashcalculatordummy;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

EditText editText1,editText2,editText3;
TextView t1,t2,t3;
TextView txtFinalTotal;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    editText1 = findViewById(R.id.editText);
    editText2 = findViewById(R.id.editText2);
    editText3 = findViewById(R.id.editText3);
    t1 = findViewById(R.id.t1);
    t2 = findViewById(R.id.t2);
    t3 = findViewById(R.id.t3);
    txtFinalTotal = findViewById(R.id.textView);
    editText1.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }
    @Override
    public void afterTextChanged(Editable s) {
    calCulateTotal(); // calling calculate method
    }
});

    editText2.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }
    @Override
    public void afterTextChanged(Editable s) {
    calCulateTotal(); // calling calculate method
    }
});

    editText3.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }
    @Override
    public void afterTextChanged(Editable s) {
    calCulateTotal(); // calling calculate method
    }
});
}  // end of onCreate() method

private void calCulateTotal(){
   String et1= editText1.getText().toString();
   String et2= editText2.getText().toString();
   String et3= editText3.getText().toString();
   int num1 = Integer.parseInt(et1);
   int num2 = Integer.parseInt(et2);
   int num3 = Integer.parseInt(et3);
   int total = num1 + num2 + num3;
   txtFinalTotal.setText(total);

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="fill_parent"
android:background="#F3E8E8"
android:layout_height="fill_parent">

<EditText
    android:id="@+id/editText"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPersonName"
    android:text=""
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.085"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.112" />

<EditText
    android:id="@+id/editText2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPersonName"
    android:text=""
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.08"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/editText"
    app:layout_constraintVertical_bias="0.196" />

<EditText
    android:id="@+id/editText3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPersonName"
    android:text=""
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.085"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/editText"
    app:layout_constraintVertical_bias="0.067" />

<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Final Total TextView"
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.474"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/editText2"
    app:layout_constraintVertical_bias="0.775" />

<TextView
    android:id="@+id/t1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="88dp"
    android:text="T1"
    android:textSize="25sp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.775"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<TextView
    android:id="@+id/t2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="T2"
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.36"
    app:layout_constraintStart_toEndOf="@+id/editText3"
    app:layout_constraintTop_toBottomOf="@+id/t1"
    app:layout_constraintVertical_bias="0.105" />

<TextView
    android:id="@+id/t3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="T3"
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.778"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/t2"
    app:layout_constraintVertical_bias="0.095" />
</android.support.constraint.ConstraintLayout>

} }

这是我的活动\u main.xml代码

package com.dinocodeacademy.cashcalculatordummy;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

EditText editText1,editText2,editText3;
TextView t1,t2,t3;
TextView txtFinalTotal;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    editText1 = findViewById(R.id.editText);
    editText2 = findViewById(R.id.editText2);
    editText3 = findViewById(R.id.editText3);
    t1 = findViewById(R.id.t1);
    t2 = findViewById(R.id.t2);
    t3 = findViewById(R.id.t3);
    txtFinalTotal = findViewById(R.id.textView);
    editText1.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }
    @Override
    public void afterTextChanged(Editable s) {
    calCulateTotal(); // calling calculate method
    }
});

    editText2.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }
    @Override
    public void afterTextChanged(Editable s) {
    calCulateTotal(); // calling calculate method
    }
});

    editText3.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }
    @Override
    public void afterTextChanged(Editable s) {
    calCulateTotal(); // calling calculate method
    }
});
}  // end of onCreate() method

private void calCulateTotal(){
   String et1= editText1.getText().toString();
   String et2= editText2.getText().toString();
   String et3= editText3.getText().toString();
   int num1 = Integer.parseInt(et1);
   int num2 = Integer.parseInt(et2);
   int num3 = Integer.parseInt(et3);
   int total = num1 + num2 + num3;
   txtFinalTotal.setText(total);

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="fill_parent"
android:background="#F3E8E8"
android:layout_height="fill_parent">

<EditText
    android:id="@+id/editText"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPersonName"
    android:text=""
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.085"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.112" />

<EditText
    android:id="@+id/editText2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPersonName"
    android:text=""
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.08"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/editText"
    app:layout_constraintVertical_bias="0.196" />

<EditText
    android:id="@+id/editText3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPersonName"
    android:text=""
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.085"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/editText"
    app:layout_constraintVertical_bias="0.067" />

<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Final Total TextView"
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.474"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/editText2"
    app:layout_constraintVertical_bias="0.775" />

<TextView
    android:id="@+id/t1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="88dp"
    android:text="T1"
    android:textSize="25sp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.775"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<TextView
    android:id="@+id/t2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="T2"
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.36"
    app:layout_constraintStart_toEndOf="@+id/editText3"
    app:layout_constraintTop_toBottomOf="@+id/t1"
    app:layout_constraintVertical_bias="0.105" />

<TextView
    android:id="@+id/t3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="T3"
    android:textSize="25sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.778"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/t2"
    app:layout_constraintVertical_bias="0.095" />
</android.support.constraint.ConstraintLayout>

---

您的崩溃可能是因为当您更改

editText1

的值时，

editText2

和

editText3

的值为空，因此当您尝试对其执行

Integer.parseInt

时，会引发异常

您可以尝试为所有

editText1

、

editText2

和

editText3

提供默认文本

0

---

PS:我知道这可以作为评论分享，但我的声誉目前只有41岁，所以我不能发表评论，所以写下这篇文章作为回答。

你的日志中发生了什么崩溃？嗨，维杰，你需要在你的问题上发布日志，让其他人知道发生了什么。我发现了一件事，很抱歉没有及时回答