Question

我尝试了很多事情，但是我的应用程序不断崩溃。

我尝试调试，然后在运行应用程序时返回此错误。

java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'android.text.Editable android.widget.EditText.getText（）'

package com.zybooks.pigdice;


import androidx.appcompat.app.AppCompatActivity;

import android.app.Dialog;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    final Context context = this;
    //private EditText playerName;
    private String name;
    private int target_score_display;
    //public TextView player_name;
    private  EditText targetScore;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //player_name = findViewById(R.id.player_name);
        targetScore = dialog.findViewById(R.id.enter_target_score);
        //playerName = findViewById(R.id.enter_player_name);



        Button start_game = findViewById(R.id.start_game);
        start_game.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // custom dialog
                final Dialog dialog = new Dialog(context);
                dialog.setContentView(R.layout.dialogbox);
                dialog.setTitle("Title...");
                Button dialogButton = dialog.findViewById(R.id.start_game_dialog);
                // if button is clicked, close the custom dialog
                dialogButton.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {

                        try{
                            String value = targetScore.getText().toString();
                            target_score_display = Integer.parseInt(targetScore.getText().toString());
                            Intent intent = new Intent(getApplicationContext(),Gameplay.class);
                            intent.putExtra("TARGET_SCORE",target_score_display);
                            Bundle bundle = new Bundle();
                            bundle.putString("TARGET_SCORE",value);
                            intent.putExtras(bundle);
                            startActivity(intent);
                        } catch(NumberFormatException nfe) {
                            System.out.println("Could not parse " + nfe);
                        }
                    }
                });
                dialog.show();
            }
        });
    }
}

试图将对话框中输入的内容传递给下一个活动。苦苦挣扎超过3个小时。

Answer 1

您只能在创建对话框之后（在onClick内部）调用dialog.findViewById。创建活动时，它没有内容，因此您无法找到其视图。例如，正确获取dialogButton

因此，当您尝试从不存在的视图中获取文本时，它将引发异常

Edittext字段未检测到。抛出空指针异常

1 个答案: