java - 当我单击下一个活动的按钮时，我的应用程序没有给我任何输出并崩溃？

问题描述

我正在尝试为羽毛球运动员制作一个随机的球员配对应用程序，但是当我运行我的代码时，它没有给我任何结果。在编写配对算法之前，如果我只是使用意图值来传递 textview.setText(intent_value_xyz) 它可以正常工作，但是当我使用 Stringbuilder 传递 textview（即 textview.setText(builder)）时会出现问题。此外，如果意图值为空，应用程序突然崩溃......帮我修复

mainactivity的java代码

package com.example.happybirthday;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;

import android.os.Bundle;

import android.view.View;

import android.widget.EditText;

import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

public static String EXTRA_MESSAGE ="com.example.happybirthday.MESSAGE";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


}

public void goButton(View view) {
    Toast.makeText(this, "You are ready to Go ! ",Toast.LENGTH_LONG).show();
    Intent intent = new Intent(this, second.class);
    EditText numberOfPlayer =(EditText) findViewById(R.id.numberOfPlayer);
    int message = Integer.parseInt(numberOfPlayer.getText().toString());
     intent = intent.putExtra(String.valueOf(EXTRA_MESSAGE),message);
    startActivity(intent);
}

}

SecondActivity Java 代码

 package com.example.happybirthday;

 import androidx.appcompat.app.AppCompatActivity;

 import android.content.Intent;

 import android.os.Bundle;

 import android.view.View;

 import android.widget.EditText;

 import android.widget.Toast;

  public class MainActivity extends AppCompatActivity {

  public static String EXTRA_MESSAGE ="com.example.happybirthday.MESSAGE";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


}

public void goButton(View view) {
    Toast.makeText(this, "You are ready to Go ! ",Toast.LENGTH_LONG).show();
    Intent intent = new Intent(this, second.class);
    EditText numberOfPlayer =(EditText) findViewById(R.id.numberOfPlayer);
    int message = Integer.parseInt(numberOfPlayer.getText().toString());
     intent = intent.putExtra(String.valueOf(EXTRA_MESSAGE),message);
    startActivity(intent);
}

}

MainActivity Xml

<LinearLayout xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="vertical"
xmlns:android="http://schemas.android.com/apk/res/android"
tools:ignore="ExtraText">

<androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:layout_editor_absoluteY="178dp">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"

        android:layout_weight="0"
        android:text="@string/person_text"
        android:textSize="30sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2" />

    <EditText
        android:id="@+id/numberOfPlayer"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_weight="0"
        android:ems="10"
        android:gravity="center"
        android:hint="@string/enter_no_of_players"
        android:inputType="number"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        tools:ignore="MissingConstraints" />

    <Button
        android:id="@+id/goButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="goButton"
        android:text="@string/go_text_onButton"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/numberOfPlayer"
        app:layout_constraintVertical_bias="0.495" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="0"
        android:text="@string/first_view"
        android:textSize="24sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>


</LinearLayout>

SecondActivity Xml

 <?xml version="1.0" encoding="utf-8"?>
 <androidx.constraintlayout.widget.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"
  tools:context=".second">

<TextView
    android:id="@+id/textView_second"
    android:layout_width="387dp"
    android:layout_height="704dp"
    android:gravity="center_horizontal"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

标签： javaandroid

java - 当我单击下一个活动的按钮时，我的应用程序没有给我任何输出并崩溃？

问题描述

解决方案

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