操作栏中的“后退”按钮不起作用-为什么？

Question

Android操作栏中的后退按钮不起作用。每当我按“后退”按钮时，该应用程序都会关闭，然后再次需要将其打开。

我已经附上了代码。

这是紧急活动。

Emergency_activity.java

public class Emergency_activity extends AppCompatActivity {
    EditText number1, number2, number3;
    TextView contact1, contact2, contact3;
    Button add1, add2, add3, msg1, msg2, msg3;
    public static final int REQUEST_MESSAGE = 1;

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return super.onSupportNavigateUp();
    }

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

        number1 = (EditText) findViewById(R.id.number1);
        number2 = (EditText) findViewById(R.id.number2);
        number3 = (EditText) findViewById(R.id.number3);
        contact1 = (TextView) findViewById(R.id.contact1);
        contact2 = (TextView) findViewById(R.id.contact2);
        contact3 = (TextView) findViewById(R.id.contact3);
        add1 = (Button) findViewById(R.id.add1);
        add2 = (Button) findViewById(R.id.add2);
        add3 = (Button) findViewById(R.id.add3);
        msg1 = (Button) findViewById(R.id.msg1);
        msg2 = (Button) findViewById(R.id.msg2);
        msg3 = (Button) findViewById(R.id.msg3);

        getSupportActionBar().setTitle("Manage your Emergency Contacts");
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowHomeEnabled(true);

        loadData();

        add1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String NUMBER_1 = number1.getText().toString().trim();
                if (NUMBER_1.length() == 10){
                    contact1.setText(NUMBER_1);
                    contact1.setVisibility(View.VISIBLE);
                    SharedPreferences sharedPreferences = getSharedPreferences("saveNumber",MODE_PRIVATE);
                    SharedPreferences.Editor editor = sharedPreferences.edit();
                    editor.putString("contactvalue",NUMBER_1);
                    editor.apply();
                }
                else{
                    Toast.makeText(Emergency_activity.this, "Please enter the correct contact number", Toast.LENGTH_SHORT).show();
                }
            }
        });

        add2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String NUMBER_2 = number2.getText().toString().trim();
                if (NUMBER_2.length() == 10){
                    contact2.setText(NUMBER_2);
                    contact2.setVisibility(View.VISIBLE);
                }
                else{
                    Toast.makeText(Emergency_activity.this, "Please enter the correct contact number", Toast.LENGTH_SHORT).show();
                }
            }
        });

        add3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String NUMBER_3 = number3.getText().toString().trim();
                if (NUMBER_3.length() == 10){
                    contact3.setText(NUMBER_3);
                    contact3.setVisibility(View.VISIBLE);
                }
                else{
                    Toast.makeText(Emergency_activity.this, "Please enter the correct contact number", Toast.LENGTH_SHORT).show();
                }
            }
        });

        msg1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String NUMBER_1 = number1.getText().toString().trim();
                if (NUMBER_1.length()!= 10){
                    Toast.makeText(Emergency_activity.this, "Please enter the correct contact number", Toast.LENGTH_SHORT).show();
                }
                else {
                    Intent intent = new Intent(android.content.Intent.ACTION_SEND);
                    intent.setType("text/plain");
                    String message = "I need help. Its an emergency.";
                    intent.putExtra(android.content.Intent.EXTRA_TEXT, message);
                    startActivity(intent.createChooser(intent,"Send via"));
                }
            }
        });
        msg2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String NUMBER_2 = number2.getText().toString().trim();
                if (NUMBER_2.length()!= 10){
                    Toast.makeText(Emergency_activity.this, "Please enter the correct contact number", Toast.LENGTH_SHORT).show();
                }
                else {
                    Intent intent = new Intent(android.content.Intent.ACTION_SEND);
                    intent.setType("text/plain");
                    String message = "I need help. Its an emergency.";
                    intent.putExtra(android.content.Intent.EXTRA_TEXT, message);
                    startActivity(intent.createChooser(intent,"Send via"));
                }
            }
        });
        msg3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String NUMBER_3 = number3.getText().toString().trim();
                if (NUMBER_3.length()!= 10){
                    Toast.makeText(Emergency_activity.this, "Please enter the correct contact number", Toast.LENGTH_SHORT).show();
                }
                else {
                    Intent intent = new Intent(android.content.Intent.ACTION_SEND);
                    intent.setType("text/plain");
                    String message = "I need help. Its an emergency.";
                    intent.putExtra(android.content.Intent.EXTRA_TEXT, message);
                    startActivity(intent.createChooser(intent,"Send via"));
                }
            }
        });
    }
    public void loadData(){
        SharedPreferences sharedPreferences = getSharedPreferences("saveNumber",MODE_PRIVATE);
        String NuMbEr_1 = number1.getText().toString().trim();
        NuMbEr_1 = sharedPreferences.getString("numberValue",UI_MODE_SERVICE);
        contact1.setText(NuMbEr_1);
    }
}

在清单文件中，我添加了以下内容。

<activity
            android:name=".Emergency_activity"
            android:parentActivityName=".DashBoard" />

请帮助我解决此后退按钮问题。如果这种方法是错误的，建议我其他替代方法。提前致谢。编码愉快。