Android在LinearLayout中动态添加EditText

我试图使用按钮在现有的 editText 字段下动态添加 editText 字段。目前按下按钮没有任何作用。这是我的代码：

XML:

<?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"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#d4cfcd">
tools:context="com.zdowning.decisionmaker.MainActivity">


<LinearLayout
    android:id="@+id/linearLayoutMain"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/editText1"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:gravity="center"
        android:hint="Enter Your Question Here"
        android:layout_marginBottom="20dp"
        android:layout_marginTop="20dp"/>

    <LinearLayout
        android:id="@+id/linearLayoutDecisions"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

    <EditText
        android:id="@+id/editText3"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:gravity="center"
        android:hint="Enter Answer #2" />

    <EditText
        android:id="@+id/editText2"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:gravity="center"
        android:hint="Enter Answer #1" />

    <EditText
        android:id="@+id/editText4"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:gravity="center"
        android:hint="Enter Answer #3" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center">

        <Button
            android:id="@+id/add_button"
            style="?android:attr/borderlessButtonStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@color/colorPrimary"
            android:text="+"
            android:textColor="@android:color/background_light"
            android:textSize="18sp"/>

        <View
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1" />

        <Button
            android:id="@+id/remove_button"
            style="?android:attr/borderlessButtonStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@color/colorPrimary"
            android:text="-"
            android:textColor="@android:color/background_light"
            android:textSize="18sp"
            android:layout_margin="10dp"/>
    </LinearLayout>

    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
    <Button
        android:id="@+id/button"
        style="?android:attr/borderlessButtonStyle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@color/colorPrimary"
        android:text="DECIDE!"
        android:textColor="@android:color/background_light"
        android:textSize="18sp"
        android:layout_centerInParent="true" />
    </RelativeLayout>

    <TextView
        android:id="@+id/textView7"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:layout_margin="20dp"
        android:textColor="@android:color/black"
        android:textSize="36sp" />

</LinearLayout>

Java:

package com.zdowning.decisionmaker;

import android.graphics.Typeface;
import android.support.v7.app.AppCompatActivity;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.ScrollView;

import java.lang.*;

import static com.zdowning.decisionmaker.R.layout.activity_main;

public class MainActivity extends AppCompatActivity {
public int numberOfLines = 3;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    setContentView(activity_main);
    final Button button = (Button) findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
             getAnswer();
        }
    });

    final Button Add_button = (Button) findViewById(R.id.add_button);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Add_Line();
        }
    });
}


public void Add_Line() {
    LinearLayout ll = (LinearLayout) 
    findViewById(R.id.linearLayoutDecisions);

    // add edittext
    EditText et = new EditText(this);
    et.setId(numberOfLines + 1);
    ll.addView(et);
    numberOfLines++;
}


public void getAnswer() {
    String[] options = new String[3];

    EditText text = (EditText)findViewById(R.id.editText2);
    options[0] = text.getText().toString();

    text = (EditText)findViewById(R.id.editText3);
    options[1] = text.getText().toString();

    text = (EditText)findViewById(R.id.editText4);
    options[2] = text.getText().toString();

    int number = (int)(Math.random() * 3);
    String answer = options[number];

    TextView answerBox = (TextView)findViewById(R.id.textView7);
    answerBox.setText(answer);
}
}

任何建议都会有很大的帮助，因为我是 android studio 的新手。编写上面的代码花了我几个小时。

改变你的Add_line()方法：

 public void Add_Line() {
    LinearLayout ll = (LinearLayout)findViewById(R.id.linearLayoutDecisions);
    // add edittext
    EditText et = new EditText(this);
    LinearLayout.LayoutParams p = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
    et.setLayoutParams(p);
    et.setText("Text");
    et.setId(numberOfLines + 1);
    ll.addView(et);
    numberOfLines++;
}

add the LayoutParams to the Edittext